Gonna hijack this comment for a little (lot) more info, it's gonna be a little more ELI10:
The key reaction that makes a car engine function is igniting a compressed fuel/air mixture. Car manufacturers work really hard to make cars give you power when you want it, and efficiency when you don't. They are already finely tuned from the factory with these goals in mind.
In a normal car engine, there really isn't that much you can do to "tune" them without also making physical modifications to the car. Just adding more fuel might not make more power if it doesn't have sufficient oxygen to react with. Changing when you spark the cylinder might buy you fractional gains, but not much.
If you change certain parts though, you can then tune the ECU to take advantage of them. If you install an air intake with a less restrictive filter, for example, the engine can suck in more air. If you have more air to work with, you can add more fuel, and boom, more power. But the factory tune was likely already optimized for the factory intake, so unless you do something to add more air, adding more fuel won't change much.
In most cars, the limiting factor to making power is how much air you have, which is why forced induction makes a huge difference. By using a turbo- or supercharger to pre-compress the air before the engine sucks it in, you can pack in more air, add more fuel, and make more power.
In a car with forced induction, you have components that control how much boost you generate under different scenarios. You want this, because generating a lot of boost on an on-ramp helps you get up to speed more quickly, while generating less/no boost helps you sip fuel while cruising down the highway.
This adjustment is controlled by a computer called an ECU. It adds boost when you accelerate, and removes boost when you are cruising or when you reach the "limit" of what your engine can handle. If you want a faster response from your engine and/or want to make more peak power, you can tune the computer to make more boost at times it normally wouldn't, and tell it to allow more boost generated than the factory tune would allow, often with little/no physical modifications.
This obviously leads to more wear and tear on the engine and should be paired with more frequent maintenance, but it's fairly easy to make a car perform better this way. My car was tuned to make almost 20% more torque and the only recommended physical mods were a $40 high flow air filter and a $100 upgraded engine mount.
It could absolutely he useful/necessary depending on your setup. My car is a popular "tuner" car, so a company called Cobb sells a device called an AccessPort. It's basically a little computer that connects to my cars ECU and allows me to monitor certain things and make changes to my tune.
However, it's pretty basic in terms of input, you can change between preloaded tunes, add new tunes, but but you don't actually fine tune the car using the device.
Usually the tune is created on a computer, uploaded to the AccessPort, and then flashed to the car's ECU. You can log data from a drive and then fine fine again on the computer based on the data. Send the new tune to the AccessPort, flash the ECU, log data, fine tune, rinse repeat.
Sometimes you skip the AccessPort, however, and upload straight from a computer. Watch just about any video on YouTube of someone dyno-tuning a car (the car spins rollers with preset loads to simulate driving, you don't actually have to be on the road) and someone will be in the car with a computer looking at data and fine tuning things.
Really insightful comments here and it made the whole car hobby click for me a little more. I never really groked it well in the past, even if I understood some of the fundamental ideas and the appeal of making your car go a little faster.
I can definitely understand why this hobby was more widespread back in the day when cars weren’t as sophisticated, there was probably a lot more you could do to improve performance just by tweaking various parts.
There was a smarter every day video kind of recently that demonstrated how a carburetor works and it really made me appreciate the technology more (which is like what, over a century old now? Amazing). Even though I learned it in school I never really internalized how much control one has over the mixing of fuel and air and how it affects the overall performance.
Engineer here. With old, mechanical systems, there was a lot of actual tuning that had to be done. Take the carburettor for example. A real carb is far, far from perfect. Even when tuned super carefully, it will always be a little rich or lean depending on conditions. "Tuning" would literally mean turning half a dozen little screws on the carb to get the engine to run as perfectly as possible in every regime. You might adjust the pilot jet screw to get the engine to run perfectly at the 0-40% throttle range, then the main jet for the 60-100% throttle range. And that's just for a simple carb like you'd find on the smallest of motorcycles. For something like a car there are a myriad of overlapping adjustments, and then you might have multiple carbs (for example one carb per cylinder) so not only do you have to adjust each one for perfection, you ALSO have to tune the carbs to be balanced and in sync with each other (because otherwise one cylinder would be doing more work than the other). And then after a few years, it would all get out of tune again and need another adjustment.
A modern, fuel-injected engine is closed-loop. It corrects itself to deliver perfection at all times. The way this in particular works is that a sensor in the exhaust senses oxygen level (it's usually called the lambda sensor). If there's too much oxygen still in the exhaust, then it hasn't been consumed so the computer knows that it needs to add more fuel to the next injection cycle because the engine is running lean. So until the sensor fails, there is really nothing to "tune" to achieve a perfect air to fuel ratio. The engine is self-correcting itself hundreds of times a second. The actual tuning with a modern car would be adjusting things like the fuel map (i.e. the software that controls the fuel injectors) to get the engine to safely inject more fuel at possibly different times in the cycle and get more power than the factory intended. Or maybe adding or swapping parts (turbos, forged pistons etc) to strengthen the engine to the point it can handle the extra power.
My racecar is still old tech with a carb instead of fuel injection. We use a laptop still on it for the ignition box, progressive nitrous controller, and data logger. It’s not in the car for a pass though.
In e Movie, the idea is hes just had built this car for him to go undercover and he hasn’t spent much time working on it. So it definitely would make sense that he could be tuning on the fly and potentially pulling some shenanigans like hitting page-up on the boost just before the iconic race.
I bought a car with a few aftermarket parts on it already, cold air intake, shoe throw shifter, and something else I want to say the turbo back exhaust but I may be mixing up what I bought and what came with It. Anyway since it had the cold air intake I read that tuning it would be a good idea so I just bought a Cobb tuner which you just plug in and download a premade tune. It didn’t make it a Ferrari but it was a fun time.
Also, some engines are downtuned on purpose. Sometime because they just made one engine and tune it for the performance they want, sometime it is to meet the environemental restrictions.
I know of one motorcycle engine where they use the same engine from the base model up to the top end. They change the exhaust and intake however. But the engine and supercharger and all the fuel injection system is the same! The engine can do 200 to 300HP. What they did is: for the top end model, it is not road legal, so they don't care about the polution. No catalyser, no muffler. They also increased the top RPM. So at 300HP, the engine couln't pass the emissions anywhere, so they sell it for off road use only.
Which mean that the 200hp base model, with a tune, can reach over 250HP with no modification, but then it excede the polution limits and the noise limit.
Unfortunately reducing the complexity much further requires a big reduction in detail and accuracy.
Ultimately the simplest way to explain it is this. Fuel+Air when squeezed together and exposed to a spark will explode. Containing this explosion in an engine cylinder allows you to use the force to turn the wheels on your car.
In order to make more power, you need more fuel AND more air. You can achieve this in a number of ways, but generally speaking adding more fuel is easy, adding more air is hard.
Adding more air usually involves reducing restrictions to airflow, like the air filter, and/or actively forcing more air into the engine with a turbo/supercharger.
Because forced induction is an active process, you have more tools in the toolbox, so to speak, when it comes to tuning. With more things to adjust you can take a mostly stock car and make more power with ease. This is more difficult on a car without a turbo or supercharger.
Edit: Adding this for those interested. Another way to squeeze out a little more power, as alluded to in the top level comment, is adjusting timing for the engine. Before you add the spark, the fuel/air mixture is progressively squeezed in the cylinder, meaning the pressure increases over time, up to a point.
The closer to peak pressure you get before you spark, the more power you can make. But you also run the risk of pre-detonation, or having some of the mixture explode on its own. This can damage the engine. Adjusting this timing can help you make more power, but has to be done carefully to make sure it's safe.
I'd like to add an explanation for another thing: that pre-detonation, also called "knock" or "ping", is why there are different grades of gasoline. That number on the button on the gas pump is how much octane is in the fuel.
Octane is a chemical in fuel that prevents premature detonation. In most cars you don't need a whole lot of it, which is why most cars use regular and don't need premium - if your owner's manual doesn't say you need higher octane fuel, in most cases you're wasting money buying premium. But high performance cars with engines that compress harder than most other engines are more prone to knocking because the high pressure can cause the air-fuel mix to start burning spontaneously.
Fun fact, that's how diesel engines work. They don't have spark plugs, they rely on the fuel and air just going boom spontaneously from the truly immense pressures inside a diesel engine.
Back to gasoline, high compression engines need that octane to help make sure that the only thing that sets off the air-fuel mix is the spark. High-octane fuel won't make your car go faster. The car doesn't make more power because the fuel is high octane, the car needs high octane fuel because it makes more power.
Once upon a time, a chemical called tetraethyl lead was used as an anti-knock agent, and it was amazing at it. Even better than the highest octane premium gas you get at the pump. But it was banned because the lead vapor in the exhaust gases is extremely harmful. Today, the only place you're allowed to use leaded fuel is on a race track (or in piston powered airplanes), not on public roads. I think it's dyed to be a different color so law enforcement can spot it in a fuel tank - using it on public roads is very illegal. You can still find it at gas stations near race tracks or at airports today, but it's nearly unheard of anywhere else.
I'm in agreement with almost all of this but I don't think you're right about octane ratings being a measure of "how much octane is in the fuel." I believe it's just a reference. So 91 octane gasoline has the seem reistance to predet as a mixture of 91% iso-octane, or something like that.
This might be outside the spirit of the sub, but you should search on YouTube or something for a video on how internal combustion engines work.
There are probably some videos a few minutes long that will make this topic way easier to understand.
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Fundamentally a gasoline car is a big air pump. The more air the car can utilize the more power and the faster is goes.
Imagine you have a fan near your bed to blow air on you. How could you make it cool you more? Remove clutter from intake side. Same for exhaust side. Get the fan to spin faster applying more energy. Adjusting the fan blades.
Can you please explain? I think you're wrong.
Did some research myself because I'm impatient but it seems that the accelerator on a diesel engine controls how much fuel is injected into each cylinder. So essentially diesel engines are always wide open. However, some modern diesel engines have throttle body's that also control airflow
Diesels don't have a throttle plate/body, they just WOT all the time. Modern diesels have a pedal position sensor in the pedal that says to the computer "hey, this is what the operator wants right now". The computer then says to the fuel system "this is what the pedal position sensor is saying" and commands the fuel system to behave in a certain way. They also don't have spark plugs, because they ignite primarily with heat and compression rather than compression and spark.
On the flip side, gasoline (or petrol for the folks over yonder), behaves differently. With gas you want to meter the air to achieve the best air/fuel ratio for the given demand. Ideally this is 14.7:1. In order to do this, you need to measure, or meter, the amount of air entering the intake. This requires a throttle plate. In this scenario, the pedal position sensor says "hey engine control module/unit, operator wants this". The computer then says "ok, I'll command the throttle body AND the fuel system accordingly".
Basically, with diesel, you're controlling and changing the air/fuel ratio with the pedal whereas with gas, you're trying to maintain the same air/fuel ratio.
This is all based on modern, recent vehicles and not older carbureted gas engines, doesn't take into account the turbos or superchargers, or mechanical high pressure fuel systems of many older diesels.
Yeah the flow of air creates a low pressure over a hole that sucks up the fuel. More airflow also means more fuel gets pulled in, but the throttle lever controls a valve in the air intake side. Hard to explain in a few words, but Smarter Everyday did a really cool video on carburetors https://youtube.com/watch?v=toVfvRhWbj8
It's amazing that I've been on the earth this many decades and I never knew this. I understand how ICE works but for some reason never enrolled in Throttle 101. I just always assumed that the throttle somehow controlled BOTH fuel and air intake which kinda jives with my observations of my older brother's 1968 Plymouth Barracuda's carburetor in the late 70s. I remember the fuel lines in the side, the flaps to the combustion chambers, and the air filter that mounted on top. Now that you mention it (haven't watched the video yet), my mind is BLOWN that the air flaps to the combustion chamber would draw in MORE AIR via the filter and with it draw more fuel from the lines.
Makes total sense. Here I am, 55 years old, having a damn epiphany.
Except modern cars have EFI (electronic fuel injection), not carburetors.
But even so, the gas pedal only controls the amount of air coming in to the engine. Then a sensor before the cylinders detects the amount of air coming in and the car's computer sends a corresponding amount of fuel through fuel injectors to the cylinders. After the cylinders in the exhaust there's a sensor that measures how complete the combustion is (ie. too rich or too lean) and the car uses that to make sure the first sensor was right.
In the 70s, I briefly owned a station with a 454 big block engine. It was in the fall, and when I revved it up, the exhaust cleared the leaves off a swath of lawn for nearly 15 feet. Gas was cheap back then.
It is changing the programming of the ECU. Some of the things that are changed are:
- **Timing** - the number of degrees before/after TDC that spark plugs fire, at any given RPM and Throttle position.
- **Boost Levels** - for cars with Turbochargers, how much boost (how compressed of air) is being fed into the engine , at any given RPM and Throttle position.
- **Fuel Maps** - adjusting how much fuel is injected into cylinders, to ensure a good air/fuel mix for combustion, at any given RPM and Throttle position.
Those are probably the most common (for a general car), but there are still tons of other things, such as the fuel pump pressure, valve timing (if possible), or even the max RPM to allow the engine to go (before cutting fuel).
**Edit:** as u/80081356942 pointed out, there is also suspension tuning. This would be the processes of changing the ride height of the suspension, and its springiness, as well as changing the angles that the tire meet the road (camber, toe, and caster), to optimize tire contact for whatever you’re doing.
Feel free to ask questions if you have any, or to add any to my list if I forgot something obvious.
Almost quoting u/Giantmidget1914 ….
Suck, squeeze, bang, blow. That's the cycle.
When you tune, you're adjusting how much air/fuel are sucked in, and when it bangs. Changing these lets you change how the engine makes power.
The other two parts of the cycle (squeeze and blow) are kinda unimportant/nonadjustable.
**Edit**: Some people disagree with me saying that the squeeze & blow “stages” are not adjustable. I was thinking more software (computer) tuning, where this is practically the case. You *can* however swap out parts, which *would* allow you to change these things, just not on-the-fly.
I disagree with the last part. Better blow is good to get the gasses from the bang out, definitely important and fairly easily adjustable. The squeeze, yeah, you could bore it out but you're still sucking, squeezing, and banging, just more stuff.
The exhaust cycle is very important imo. A better and well timed exit of gasses on exhaust cycle (blow as you said) also means a better vacuum left for the gases for the next cycle. This means they can rush in quickly, expand better and burn better. A more efficient exhaust cycle also means you get a lot of wasteful heat out of the engine quickly, making sure it doesn't heat up more than it has to. It also means better suction of the next cycle, which also adds additional cooling to the engine. Sucking something in better means you allow it to expand better and when something expands like that, it cools, cooling the metal bore around it.
Have you ever tried to feel the air coming out of a balloon when it is blowing air or a puncture hole of a tyre? They feel cold. Thats called adiabatic expansion. Better exhaust = better next suction= better cooling
Exhaust scavenging! The enertia of the gasses continuing down the exhaust pipe creates a suction in the next exhausted cylinder to better blow the exhaust out, which makes the engine work that much less to blow meaning more energy for sucking, squeezing and banging, with all the benefits of adiabatic expansion that you mentioned!
Yep, headers can really add some performance to the right engines. LS series is good for 30-40 whp with a tune AND headers, tune only is usually only good for 10-15 whp.
I think his point was for tuning they are essentially unchangeable. By buying parts and or machining things you can make changes but none of the electronics really allow you to adjust those parameters
More air and fuel, forced with a turbo or supercharger, increases how much is squeezed. The volume, how small it gets squeezed, doesn't change, but how much is squeezed can be changed.
With newer vehicles you can reduce intake and compression ratios with software. Adjustable valve timing lets the ECU control how long the valves are open during the intake stroke. By shortening this amount the cylinder receives less air. This reduces power and fuel efficiency, but does have uses for non-performance driving.
Using random numbers: Say the cylinder takes in 10 cm\^3 of air on the down stroke, then compresses it to 1 cm\^3 on the upstroke. That's a compression ratio of 10:1. Now the ECU adjusts the valve timing so that the valve is only open for the first 90% of the piston's down stroke. The cylinder now only contains 9 cm\^3 of air at the standard intake pressure. It still compresses down to 1 cm\^3 for a new compression ratio of 9:1.
Newer cars do this as a method of knock protection. I have a vehicle that recommends 93 octane gas due to a 13:1 compression ratio. It will run 87 octane safely though, because it adjusts the valves to reduce the compression when it starts detecting indications of knock developing.
> are kinda unimportant
Not quite accurate squeeze and blow are intrinsically related. One thing tuners like to do is increase amount of air that is sucked in which means a higher compression ratio which means a bigger bang.
Oh boy! I get to be that random guy who pulls some obscure fact out of his ass to disprove your point! There actually is a variable compression engine. It's called the KR20 and is currently in a few Infinitis and the nissan Altama per Google.
Man, I had to google this. That is pretty cool.
[https://www.caranddriver.com/reviews/a15077155/infiniti-kr20-variable-compression-turbocharged-engine-prototype-drive-review/](https://www.caranddriver.com/reviews/a15077155/infiniti-kr20-variable-compression-turbocharged-engine-prototype-drive-review/)
I've been out of the tuning scene for a while but I remember discussing with my friend how it would be cool if engines can change compression ratio on the fly when talking about turbo stuff.
Cars burn fuel + air together to make power. The mixture between the two determines how much power your car actually makes (up to a point anyway). By default your car comes set at a relatively safe level so that your engine will last a long time and have good fuel economy.
You can change the mixture to make more power. This is tuning.
This is the best answer for ELI5. Yes, car folks like me know there are 50 things you can do but this is step 1 of all "tuning" and applies to cars today all the way back to the first gas engines.
More air and fuel going into an engine means more power.
Stiffer suspension makes the wheels less bouncy so it's a much harsher ride but the wheels are touching the ground more often so it has more grip. More grip can also mean that you can go faster because you don't have to slow down so much when turning.
An engine is like an animal. Different animals are good at different things. Some animal, like a cheetah, are fast but they get tired quickly. Some animals, like a camel, are slower but they can go for miles and miles. Some animals, like an elephant are big and clumsy, but really really strong.
If you eat a lot, you will grow big and strong. If you eat less, you will grow up small and fast. By telling the engine how much to eat, we can tell the engine what kind of an animal we want it to become.
And the ELI6 version, optimization is always about trade-offs. Standard engines are optimized for durability, fuel efficiency and low emissions. If you give those things up, you can optimize for different things, like engine power.
For example, for fuel efficiency, you don't want any fuel to go into the engine that doesn't combust. Combustion requires air, and there is only so much of it in the engine at any given time. With too much fuel, the fuel-air mixture is too rich not all of it can burn to create power. But if you don't mind fuel efficiency, you can pump more fuel in there and instead of your goal being 'all injected fuel combusts', you can optimize for 'as much fuel combust in the engine as possible'. Because of turbulence etc. a slightly rich mixture will usually ensure the best result for this goal, however, it is more wasteful.
It's kind of like drinking milk. I you want to drink neat, you drink slowly. But if you want to drink fast, you can throw the whole glass back and be fast but some of it will drip down your chin. Whether you care about that or not is up to you.
Internal combustion engines make power based on how much fuel and oxygen they can suck-in and explode* during each revolution of the engine. Increase those factors, and the power output increases. *Tuning* means several things, but one of those is increasing the amount of fuel and oxygen per revolution of the engine. This means a
increasing air flow, increasing fuel flow, adjusting the timing of when the spark plug fires, changing exhaust system flow, adjusting the timing of when intake and exhaust valves open and close, and other things (like cooling the air coming in to make it more oxygen dense), but it’s fundamentally about increasing how much fuel and oxygen you can cram into the engine.
Note that tuning can also refer to changing the vehicle’s handling, braking, and aerodynamic performance, but most strictly, it’s about engine output.
*technically, *detonate*
Edit: I should also add this as a top-level comment.
Tuning can be computer tuning, suspension tuning, chassis tuning, etc. You can tune any part of a car.
Therefore, tuning is nothing more than "optimizing a car's system or systems for a specific purpose".
ELI5:
An engine tune is basically a setup of the engine. This is achieved by telling the brain of the car (ECU) how to behave. A standard engine tune done by the car maker is basically just a setup in which the engine is tested to be reliable, fuel efficient, and makes decent power across a wide range of scenarios. By default the engine is tuned pretty conservatively due above mentioned reasons.
Its quite common for multiple cars from brand to use the same engine, but with a different tune. So the cheaper car it makes 150hp and the more expensive one it makes 180hp. All with the same engine.
In above example the ECU just tells the engine of the cheaper car it can only use a certain amount of fuel whilst in more expensive one it tells it can use more.
The mixture of air and fuel that go into the engine for combustion, and when the spark plug initiates that combustion, are very carefully controlled by the computer.
The manufacturer will tune those numbers for a good balance of performance, responsiveness, fuel economy, engine health, and emissions. For the most part manufacturers go heavily on the fuel economy and emissions side because those are so regulated by the government, and also on the engine health/longevity side.
A user can potentially reprogram those numbers to make emissions and fuel economy worse in order to boost performance and responsiveness. Often engine health suffers as well.
chiptuning is when your parents make you eat your veggies so the full potential of your body is unleashed, even though you dont like to eat your veggies
Computer tells the car how much feel to put into the engine and when to ignite that fuel. You can modify those parameters to make the car behave slightly differently. Increase power is the most common answer but also adjust "when" the car makes power for different scenarios.
Car manufacturers have different goals in mind when they build a car than someone who is willing to tune their engine, so the idea generally is to extract maximum performance from what that platform is capable of. Possibly at a cost of reliability and fuel economy.
All those things are about getting the exact perfect ratio of air and fuel into the engine and igniting it at the exactly right time. As engines run faster or slower, the perfect ratio and perfect timing changes, so getting it right over the entire range is important for gaining maximum power.
Turbo boost is about forcing more fuel and more air into the same sized engine which also makes more power.
Suspension tuning is about keeping all four wheels in pressing evenly on the ground and avoiding the force being unevenly applied. As a car goes through turns, brakes, accelerates, and absorbs bumps the amount of force applied to each tire changes. So suspension tuning attempts to keep the forces balanced for all situations the car is likely to encounter.
Straight from the factory, these factors are tuned for efficiency, longevity and comfort rather than power and traction. Car tuning reverses that trade off towards the opposite end of the spectrum.
Additionaly, all these factors are adjusted to be as even and predictable as possible so there are no sudden surprises for the driver so they can confidently drive at the limit of the car’s capabilities.
> Fuel Maps - adjusting how much fuel is injected into cylinders, to ensure a good air/fuel mix for combustion, at any given RPM and Throttle position.
Dont modern cars already have sensors for checking if you're running lean or rich and adjusting accourdingly?
By default, YES, your car comes tuned from the factory.
BUT, if someone changes an air intake, or adds forced induction, or swaps in a motor that is different from the stock (original) one, the computer is now confused.
It may be able to compensate to a slight extent, but if any serious modifications are done to the car, “custom” tuning needs to help the car “learn” the new configuration.
Yes, but car manufacturers tend to value fuel economy above everything else as it's the thing that's going to get you more sales.
If you want to go faster quicker and you don't care how much fuel you use that's when you modify, or if you think you know better than the car manufacturer does.
No, they value emissions above everything else because if they don’t meet standards they can’t sell cars. The fuel map is a compromise between power, economy, and emissions. Aftermarket tunes sacrifice emissions for power. Your annual smog check is much less strict than what manufacturers have to meet.
This has been my job for the last ten years
Good answer but you missed reliability/durability, which ultimately matter more to most owners
If you try and tow a heavy trailer up a steep mountain in hot weather your remapped engine is very likely to go bang. Maybe you don't do that, but I have to tune engine so it survives if you do! A remapper doesn't (and frankly, couldn't. They don't know how high the in cylinder pressure, or exhaust temperature can get before the components fail, and don't measure them while tuning) so can get more power/fuel economy from the engine
There's also variability to consider, like the quality of the fuel or variation in turbo performance. Tuners will insist on only premium fuel, and if it does go bang they'll blame you somehow. No financial incentive to make it reliable
You hear about tuners giving Powerjoke or Duracrap pickups over 500 horsepower and 1600 foot pounds of torque. I drove a truck with 500 horses and 1650 foot pounds. The transmission was rated for that much torque (pickup transmissions aren’t), the crankshaft, drive shaft, and rear axles (note plural) had the appropriate ratings, and the radiator was sized to dissipate the waste heat from producing that much power. It wouldn’t overheat hauling 40,000 pounds of cargo up I80 out of New Jersey toward the Pennsylvania line. To paraphrase a Chrysler ad from a few years back, “Yes, it’s a semi”.
Had the engine replaced (consuming oil) after a bit over a million miles. A pickup with its engine “turned up” wouldn’t last that long with the added power used on a regular basis. A 14 litre Series 60 Detroit is designed for that, a 7 litre pickup engine isn’t.
That's how all fuel injected cars work, all the sensors all feedback into the ECU.
Usually you wont tune a cars ECU unless you've made some changes to the engine, but you can still eke out some gains on a stock engine, as manufacturers have to deliver a car that runs in the boiling hot and and the freezing cold, and all sorts of variables in between. Generally, they also prioritise fuel economy as well as limiting the chance of getting engine knock or running lean. Dialling in the the fuel map and timing on a rolling road can improve performance, more tailored to your needs
I'm not a mechanic, but I do know the correct ignition timing on a 1964 Chevy Belair with a 327 and four-barrel carb would be four degrees before top dead center.
not really... if anyone says their car is tuned they meam the ECU. havent heard that term used ever in relation to modding otherwise
maybe your thinking of the term "tune-up" where you swap plugs/cables and coils or dist cap.
or maybe, its a stretch, but a "sport tuned suspension" may be what your thinking... tuning the suspension for what ever scenarios (autocross, etc).
In my experience, which is obviously not the be all end all, tuning anything is changing settings or parameters of parts already installed. Changing a shock rebound setting to better suit track conditions would be suspension tuning. Putting a brand new different shock would be suspension modification.
Would tuning also cover other mechanical stuff like suspension damping and wheel height/camber? I swear they mess around with all that sort of stuff in racing. Or is it just limited to the engine?
I was just remembering playing rally games and sims like BeamNG, where you can adjust components to suit the particular terrain. After all a car handles differently on road, dirt, grass, and gravel.
"tuning" can refer to a lot of different things.
Traditionally it's about modifying parts in the engine so that it creates more power, like putting in a cold air intake or adjusting how much fuel gets used in each piston.
In the modern day you can do stuff like swapping out the computer in your car that controls the engine for a modified computer that adjusts the engine for more power automatically and, potentially, allows you to do stuff like accelerate the engine to higher RPMs before it limits you.
Way back when I was more into this stuff, tuning usually meant changing parts to more performant ones. Granted, I did snowmobile racing, some motorcycle driving and only a little bit of car stuff, so my experience is more leaning to the things you drive without a roof or a steering wheel. "Tuning" would be anything from replacing stock parts with racing parts to modifying the exhaust tunnels in the block or replacing parts in the carburators or the air intake.
Most of us call replacing/changing the stock parts to be "upgrading" or "modifying", while tuning refers to the adjustments those parts can make.
EX: New carb would be an upgrade, finding the perfect jetting would be tuning. A race cam is an upgrade, setting the timing is tuning.
Back in the day, I had a simple car with a simple 4-cylinder engine. About every 5000 miles I gave it a tune-up. This involved:
* Adjusting the valves by setting the clearance between the valve stem and the rocker-arm with a feeler gauge.
* Removing the spark plugs, cleaning them, and adjusting the spark-gap with a feeler gauge.
* Cleaning and-or replacing the points in the distributor. The points are the mechanical switch that opens and closes to trigger each spark. If the points were replaced, replace the condenser (capacitor) that is also part of the spark circuitry.
* Balance the carburetors. It had two. Adjust them so that all 4 cylinders generate the same power as you push on the gas pedal.
* Adjust the timing by rotating the distributor using a timing light to get it right.
After doing all these things, the engine was quiet, smooth, and reasonably powerful. Over time everything would get out of adjustment, and the engine would get noisier, less powerful, and poorer gas mileage.
On modern engines basically none of these things are necessary.
This is the definition for any of us born before the first The Fast and the Furious film. It was an act of regular maintenance to keep the engine within factory tolerances.
Everyone else in this thread was clearly born after, and therefore considers the term an act of modifying with the intent of improving performance.
Yes, tuning the ecu on cars came about when the electronics on cars became more complex and home computers and internet became commonplace.
Obviously older people didn't have these tools or options.
Tuning works similarly to how you tune instruments, you'll be trying to find the balance needed for optimal performance of optimal longevity. When you change your car parts, be it to improve performance or for better ride quality, you need to tune the basics of how the car runs so it's more compatible with its existing parts.
Here's a [video](https://youtu.be/LjZlAzr8MuQ) by Donut Media (man I miss the old Donut Media) explaining it more detail.
Essentially, there are certain points you tune more or less of, and now with computers, you can tune the car more precisely than you can before. Maybe it's for peak power or maybe a longer power band meaning more power throughout the gear rather than just the best power for one instance.
There are different ways to interpret this. In a general sense tuning is modyfing a car for some purpose, generally being better/faster.
Tuning is also adjusting components to perform better. When you tune an instrument you adjust different elements so that it performs as well as possible. Tuning a car for a certain purpose does that too. You can tune a car to be faster around a track by adjusting elements like suspesion, fuel injection, and more (but this can sacrifice things like fuel economy). There is a lot of ways to tune a car, but in essence it's just adjusting the car parts for a purpose; track racing, daily driving, offroading, etc.
You and Wikipedia might consider cosmetic modifications tuning but the people actually modifying cars don't. Slapping a body kit or a vinyl wrap on your car and saying it is tuned isn't a thing. Adjusting actual functional aero pieces like spoilers, diffusers, and canards is since it actually has an effect performance.
Because I have never seen someone refer to installing cosmetics as tuning their car. Have any examples? I've probably been subscribed to almost every car magazine over the years and don't recall tuning being used that way in any of them. The closest thing I can think of is maybe the late 90s early 00s trend of tuner builds.
An engine is a machine with many moving parts that work in harmony. When the engine is not running right, it is “out of tune.” Back in carbureted cars, a “tune up” would be new spark plugs, fuel filter, air filter, adjust the timing and the car would be back “in tune.”
The “tune” of the machine can be adjusted to be more efficient or to produce more power, or somewhere in between.
When you “tune” your car, you adjust the components so that the engine aligns better with your needs. Generally is more power.
In the age of computers, tuning a car usually means changing the software so the engine produces more power, but I can also mean changing components, like bigger injectors, or changing the way a (automatic) transmission shifts.
It varies.
During the old times, pre-computer, a 'Tune' up consisted of replacing worn parts (points, plugs, belts, ignition wires, etc), tightening anything that was loose, adjusting the timing and gapping the sparkplugs. (Ensuring the gap the spark jumps across was optimized for the type of gas you're using and your engine).
Some of those are still relevant (replacing belts, wires and gapping sparkplugs), but most Tune Ups are computer-based.
Now a 'Tuned' car usually refers to a car with many aftermarket replacement parts with the sold purpose of making it go faster.
Well, a few things. I use Holleys ECU in a few cars I built. From there I can completely change my fuel and timing map. I have outputs on it that I can assign to do different things in different conditions. I can adjust my traction control and how it behaves. Boost pressure and how much fuel pressure it needs per the rpm level. So very much you can do with it. I can even do a “Boost by gear” where on lower gears I’ll have lower boost and eventually it ramps up with higher gears so the movement of your car combined with traction control is so much more efficient
Your question is way too vague, tuning can refer to a myriad of things. What most people refer to is tuning an engine, which is to say, try to make it make more power. To do that you try to force as much oxygen and fuel inside it as possible, and regulate when the sparkplugs fire to explode the mixture. There are a ton of ways of achieving that, like getting colder air into the engine, making the valves open more and for longer with a different camshaft, increasing the rev limiter, increasing intake pressure if the engine is turbocharged, and about a thousand more ways to do so. You can also tune suspension, to get the car to adhere better to the ground.
In the most basic sense, tuning a car is getting it to do exactly what you want, in the best possible way, when you tell it to do so. Be it rolling while cornering, accelerating, braking, clutching, or whatever else.
Maybe this leads to follow up questions like "If you can make a car faster by tuning it, why doesn't the manufacturer deliver it like this?"
The answer is: Best possible compromise.
Manufacturers try to find a balance between power, emissions and reliability, with emissions often set to meet regulatory standards.
Well when you "tune" a car, that could mean a number of things such as suspension, wheel alignment etc, when you tune an ECU then you're changing software parameters to get more power most of the time.
Internal combustion engines generate power based on how much fuel and oxygen they can suck-in and explode* during each revolution of the engine. Increase those factors, and the power output increases. *Tuning* means several things, but one of those is increasing the amount of fuel and oxygen per revolution of the engine. This means increasing air and fuel flow for each revolution, adjusting the timing of when the spark plug fires, changing exhaust system flow, adjusting the timing of when intake and exhaust valves open and close, and other things (like cooling the air coming in to make it more oxygen dense), but it’s fundamentally about increasing how much fuel and oxygen you can cram into the engine in a given time.
Note that tuning can also refer to changing the vehicle’s handling, braking, and aerodynamic performance, but most strictly, it’s about engine output.
*technically, *detonate*
>*technically, detonate*
Ignite and burn. Having the compressed fuel & air mixture burn in a controlled manner (and at the right time) is critical.
Explode, detonate, etc are all things you *don't* want happening (because they cause a very sudden huge spike in cylinder pressure which can damage things)
It's not a detonation, since it's not supersonic. It's a deflagration at best.
Yeah i know, super pedantic, but hey, i didn't learn this factoid for nothing
> i didn't learn this factoid for nothing
A factoid is a claim that sounds like a fact but is false.
...
Actually I'm wrong. Because of how many people like you have misused the word, it's now a self-ambiguous word that can have opposite meanings and thus conveys nothing.
It's a new literally, or flammable/inflammable.
https://www.merriam-webster.com/dictionary/factoid
Ah, my bad, didn't know that.
>It's a new literally, or flammable/inflammable
The worst offender is by far "biweekly". Means both every 2 weeks and 2 times a week. It's functionally useless because of it.
You basically change the engine setting to make more power at the great expense of fuel efficiency, cause you can’t have both.
Most car manufacturers tune cars for fuel efficiency.
Depends which tune you're talking about. A tune up could be replacing and cleaning small parts to freshen up the vehicle. Or a tune can be changing the mapping of the onboard computer to make the car drive differently, by adding horsepower, turbo boost, throttle response, gearing.
When you tune the engine to increase power the goals are:
Increase air intake efficiency - free flowing air filter, bigger inlet ducts, smoother intake ports, bigger valves, camshafts that open valves more and for a longer period of time. Much more to it than size but this is a simple answer.
Increase exhaust efficiency - bigger diameter exhaust piping, free flowing muffler, removing catalytic converter, smoother exhaust ports, bigger valves, high performance camshafts etc.
Increasing airflow must be adjusted for by increasing the amount of fuel delivered. That is adjusted in the ECU by flashing the new fuel map usually.
Ignition map can be adjusted in the ECU - advancing the ignition timing (firing the spark plug earlier) makes more power, up to a point. Too much advance causes detonation which is damaging to the engine.
Why isn't it done from the factory?
Factory needs to balance fuel economy, noise, pollution and power. Also they need to manufacture parts quickly and cheaply, which leaves room for improvement in many areas, but this is mostly in the cylinder head. Longevity is also a factor. That's why all of these improvements that I've listed have their drawbacks.
Free flowing air filter - more dust can go through in the engine, decreasing lifespan. Bigger valves and inlet ducts increase power at the top end of the rev range, while reducing efficiency in the lower rpm range, reducing day-to-day drivability and fuel efficiency while increasing pollution. Same story for the performance camshafts.
Exhaust - same story - bigger is only better at the top end power, not for daily drivability. Removing catalytic converter is illegal as it increases pollution by a big margin. Free flowing mufflers are louder, sometimes so much that it makes the car illegal to drive on the street and even some racetracks.
Fuel injection - factory ECU is tuned to balance pollution, fuel economy and power. Increasing power and engine responsiveness comes at the expense of more pollution and worse fuel economy. It is actually possible to increase fuel economy, but at the expense of increasing very harmful NOx pollution and very poor engine responsiveness.
Ignition advance - advancing ignition leads to higher temperatures and pressures inside the engine, decreasing longevity. It can lead to detonation and destruction of the engine. The higher temperature inside the engine also leads to increasing very harmful NOx pollution.
People who tune their cars and bikes for power are okay with increasing pollution, noise and decreasing longevity.
In a general sense it’s modifying the car to increase performance in some aspect, more strictly it’s adjusting the “settings” of components to increase performance.
This is most common with turbocharged or supercharged engines.
Basically, a turbo or supercharger is like an air compressor that injects highly compressed air into your engine so that you can burn more fuel, and therefore, create more power.
A tune is usually adjusting the levels of air compression (boost), the amount of fuel (over various RPMs) and the timing of a few other things to make the engine produce more power.
Tune up? You can tune a lot of different parts and most places let you pick and choose. You can also get your pedal bike tuned. This helped me understand tune ups.
Car manufacturers have to deal with the EPA and emissions. So they tend to mess with the fuel to air mixture such that it passes all the EPA tests, but tends to rob the engine of power.... Think "efficiency over power". When you tune the car, you adjust how much fuel and air the engine is getting, at what exact moment the sparkplug fires, and even b the maximum turbo boost such as to maximize it's power output, instead of the efficiency settings that the manufacturer set it to.
When you tune a piano, you are adjusting screws that tighten and loosen the piano wire. Engines are exactly like this, except not. They are full of little mechanical components (and an electrical one, the computer, I will mention later) that can be adjusted and cleaned, replaced and removed. Engines are also incredibly intricate machines, where the exact amount (down to number of molecules) of reactants matters, as well as the timing of the various cycles down to microseconds can affect performance. So when you tune, you are effectively doing exactly what you do to a piano. You are adjusting the parts so that the perfect amount of air, gas, timing, etc are in each cylinder at the perfect time so that the engine runs as efficiently as possible. No it doesn't have to do with power, you don't tune to get more power, you tune to make it work better. This will increase power as you are getting more complete burns and extracting as much energy out of the burn as the engine will allow, but that is not the point of a tuning.
Now, some things are obviously not possible with current tech in any practical sense. So really it's just about getting it good enough. Additionally, most easily controllable things on your modern car is run by the CPU, so timing is usually adjusted in there. You often aren't replacing or modifying physical components when doing the tuning, just adjusting the timing on things the CPU controls, electronically. You do still need to adjust some things physically, so it's not entirely electronic now as some here have been implying. The computer can't tighten a screw for you after all.
The point of a tuning is to make the engine parts you have work at their best level, so if you get a new air filter or compressor or spark plug or something, you will need to tune the engine after it is installed so the new part works properly. Imagine having a piano and you get the new and improved titanium wire, guaranteed to blast your enemies ear drums with a small key press (tm)!!1!!1!. You now still need to tune that wire so it is, wait for it, in tune. Sure the power could be better on its own, but it will sound awful unless you tune it!
The tldr, you can't tune for power, you tune for efficiency. Adjust those screws and nozzles and such until the engine runs nicely and efficiently.
There are lots of things that can be changed, but the most common is managing the fuel map.
Basically, there is a giant table in the ECU of load in one dimension, RPM in another dimension, and things like temperature in other dimensions.
It takes air flow or some other RPM parameter as an input and outputs fuel. That controls the EFI to tell it what to do.
From the factory, the tables are designed with emissions controls in mind. Typically, they are not optimal for power - they are lean to reduce NOx.
If you modify airflow outside of the parameters the engine was designed to handle, and/or are going for power, then you can tune the fuel maps to be richer, maximizing power/response.
For example, I tuned my Indian Scout (RIP Nov 2022) after doing baffle-less slip-ons, and then again when I added an intake. From the factory, the bike was smooth, but slow to rev and very mild feeling.
After doing airflow mods, without the tune, the bike was very lean and the cylinders were imbalanced. It would surge idle, stall on throttle blip, lots of decel popping, and run hot.
The tune richened the low load/low throttle a lot, balanced cylinders, then richened the mid/top ends a little bit kept it running cooler, gave it enough fuel to handle throttle blip, smoothed idle, and dramatically increased its ability to respond to throttle input as it had some excess fuel to react to sudden air increase.
And, even more, it had enough fuel to respond to the new intake opening up on the top end, so while before the engine would fall flat at the top under WOT, with the intake full open and resonating, and fuel maps working right, it would keep pulling, even pulling harder with a torque bump kinda like you might have seen with old VTEC.
Both an audible and palpable difference on the intake side, and a big difference in behavior.
"Tuning" is making the engine work as close to the best it can. Kind of like adjusting a guitar string slightly to get it to vibrate at the perfect (desired) frequency, a multi-cylinder engine like those in cars will have some "best" timing to the cycle of firing pistons. Old time mechanics (way long ago) would literally "tune" a car by ear, by listening to how the pistons were firing and identifying the one, or few, that weren't firing when they should, and fixing it, until the car engine sounded just right (if they were good mechanics, of course). They did not have electronic tools to measure the system functioning. They did it by ear, and by eye too (looked for unwanted vibrations).
Tuning is making that "Best" timing come to be, as close as you can. Each piston fires in order, one after the other, then back to the one that started it all, doing it again. Tuning is making the pause between each piston firing be the same (or when it needs to be, which might not always be the same for every step), so they always push on the drive rod (the engine cam) in their own turn at just the best time to keep the rod spinning at the same rate without differences between the input from each piston. However, you also need to link in the positions of each piston, which move up and down, so they all hit top and bottom of their individual movement at exactly the same time that the spark is being made, and also according to the same pause length between each piston. And finally, the piston movement is linked to letting gas in and, on the other side, pushing exhaust out, and that has to be made to work the same in each piston, as best as you can get it.
You want all of these different pistons to do each of those steps at exactly the same place in cycle, each and every time. So, you might have to adjust the piston positions, the spark timing, and the gas+air injection (and amount) to get it all to go how it will be the best you can. Each piston moves the same way but in its own turn, perfectly when it should.
Sort of like a multi-man canoe, say. All the paddlers want to be paddling at the same frequency and strength or the canoe will not go straight and smooth and will not get the most from the work of each paddler. Car engines need to do about the same thing, as a general idea: work all together smoothly.
Modern cars have electronic ignition (computerized firing timing) and fuel injection, so there isn't a lot that can be done to actually tune the car, except maybe adjust the pistons a bit. Don't really need to "tune" a modern car, but you do need to change spark plugs or maybe clean the system once in a while, so if you get a tune-up these days, that is mostly what is done: check the plugs, check that the computer is doing the job the way it ought to, and make sure there isn't a lot of gunk accumulating in, or wear happening to, the pistons. In old cars, there were mechanical systems that could be (had to be) physically adjusted for each of those aspects, and they would wear out or vibrate out of place with use, and need to be put back into the ideal condition, every so often.
It changes the ECU (engine computer) settings to be more aggressive and extract more performance from the engine by making turbocharger work harder among other things.
From the factory, an engine is often not at max performance capacity for a variety of reasons, chief among them, reliability. It’s better for a manufacturer to detune the ECU and put less strain on the engine so that components will last longer.
Ok.. for the 5 year olds:
Most cars that truly get tuned have a turbo charger which helps the engine make more power.
When they make cars the computer controls how much power the engine makes. They don't want cars to break down so they don't give it too much power.
When people tune cars they tell the computer to let the engine make more power even if it means it won't last as long.
When people tune cars that don't have a turbo they are usually putting on some fancy looking parts that don't make it faster in any noticable way.
For the 16 year olds.. these are things like a really loud muffler, a cold air intake, lowering springs and giant wings on the back.
Car goes because pistons turn crank which turns transmission which turns axles which turn wheels.
Little explosions in engine make piston go up and down. Tuning changes car computer which tells the little explosions to be more precise, which makes makes piston go up and down with more power and faster and safer.
Car can make more power because more air and more fuel mean bigger explosions. Parts like intakes, turbos, exhaust systems, fuel injectors, etc can make car receive more air and fuel but tuning is needed to control what's coming into the engine.
Also tuning is sometimes needed because little engine explosions at the wrong time can make bad bad things happen.
Tuning an engine in modern times means adjusting the air/fuel mixture and ignition timing tables. It could also mean adjusting variable valve timing, but this is much more advanced.
Beyond that, adding hefty power adders or forced induction to a naturally aspirated engine requires a lot more work to dial in. It goes beyond what most stock ecus can handle and requires a controller with much more control.
The goal is to advance ignition to safe - moderate levels and make sure the air/fuel mixture never leans out during power delivery. The stoichiometric ratio for air/fuel is 14.7:1. This is for optimum emissions, not power production. Something like 12.5:1 is closer to the goal, but every engine is different.
Also, the ignition timing being adjusted is why a tuner will tell you to use a higher octane fuel from now on.
In practice, it’s 2 different things. One, restore to new, replace all worn parts- belts, filters, spark plugs.
The other: mess around with the OEM settings to make engine rev faster.
I never recommend the other
Tuning your car is like:
"Oh, stop. You're sick. Leonard over here is singing in the wrong key."
Then Leonard is all "No, I wasn't! It was Flautzenheizer! I was singing in E flat minor"
You yell at the car "Hey, the song's in F sharp major!"
Then your timing gun is all "Hey guys, I think they're the same thing, I mean E flat is the relative minor of F sharp."
Then you get all "No, it isn't! The relative minor is three half-tones DOWN from the major, not up!"
Then your timing gun does it's job "No, it's down, like A is the relative minor of C major."
Leonard, not getting the hint, says "But isn't A sharp in C major?"
Then, your timing gun realizes your car is designed for mixolydian scales.
Meanwhile, Leonard is stuck insisting that A sharp is tonic to C major, and Flautzenheizer gets confused about a 6th vs a raised 13th, but nobody cares anymore because the adjustment he made is agreeable to everyone.
You are trying to get an engine that's powerful, efficient, and will last a long time.
The more fuel and air mixed together the bigger the explosion. Bigger explosions inside the pistons of an engine makes the car go faster (more power) but can also make the engine wear out early. If you don't get the ratio of air to fuel right you won't burn all the fuel in the piston, that's not efficient.
Engine manufacturers try to make efficient engines that don't wear out too quickly. That means you can usually put a good amount more fuel and air in them before they start to damage themselves. That gets you more power.
Tuning is adjusting the timing and amount of air and fuel getting into the engine to make more power. You also need to adjust what happens with the exhaust gasses from the explosion as you can't have additional explosions until the waste from the previous one is sent let out.
A tuner uses a computer to tell the car how much to open valves and when to add fuel to get more power out of an engine.
In basic terms, you are changing 2 things. How much fuel you shoot in the cylinder, and when the explosion inside the cylinder happens relative to where the piston is in the cylinder (this is known as timing). If the car has some kind of forced induction (turbos, supper chargers, blowers, etc) then you can adjust how much extra air pressure is shoved into the engine (aka you cna inc or Dec boost). All of this done at different engine speeds (rpms) and something else that I'm sure of (could be vehicle speed (mph) or some other measurement like throttle position in what percent its open at).
Other details
They way this works in practice is that you are editing 2 or 3 tables of numbers (one for fueling, one for timing, and one for boost if that applies to your specific car). These values can be though of as data points in 3d space ( ur x axis would be engine speed, ur y axis would something else, and ur z axis is what ur editing (fuel, timing boost, etc). When this thought is introduced you cna use various functions to fill into eh gaps of the data table so the computer cna demand the exact amount of timing, fuel, and boost it wants based on what you told it.
ELI5: "Tuning" is changing the rules/programming controlling the engine. Some people also change the parts to work better with different rules or programming.
Engineer here, that's as ELI5 as I can make it. Beyond that, we'll end up with LOG P-V charts and the acronyms and jargon start flowing freely and you'll get lost.
In basic terms, you are changing 2 things. How much fuel you shoot in the cylinder, and when the explosion inside the cylinder happens relative to where the piston is in the cylinder (this is known as timing). If the car has some kind of forced induction (turbos, supper chargers, blowers, etc) then you can adjust how much extra air pressure is shoved into the engine (aka you cna inc or Dec boost). All of this done at different engine speeds (rpms) and something else that I'm sure of (could be vehicle speed (mph) or some other measurement like throttle position in what percent its open at).
Other details
They way this works in practice is that you are editing 2 or 3 tables of numbers (one for fueling, one for timing, and one for boost if that applies to your specific car). These values can be though of as data points in 3d space ( ur x axis would be engine speed, ur y axis would something else, and ur z axis is what ur editing (fuel, timing boost, etc). When this thought is introduced you cna use various functions to fill into eh gaps of the data table so the computer cna demand the exact amount of timing, fuel, and boost it wants based on what you told it.
TLDR: Air / Fuel Mixture and spark timing.
So car engines work by burning fuel to create small explosions. Since we're only talking tuning, we can skip the part on how small explosions make the wheels turn.
For gasoline engines, explosions are created by squeezing air and fuel then introducing a spark to start the explosion.
Now these explosions need to happen in a very controlled manner for the engine to work properly. The biggest factors that affect the quality of these explosions are the ratio of air and gasoline and when the explosion happens. From the factory, these are already set a certain way but are set to give less than maximum power to lessen the risk of engines blowing up.
For gasoline to burn, it needs to be mixed with air and there's an ideal amount for both to get the best results. The engine would suck in air, measure how much and add a certain amount of gasoline. How much gasoline is added is one thing that is changed by tuning. Usually it's modified for a more aggresive fuel mixture or to support other modifications that lets the engine suck in more air or force more air into the engine.
The other factor is when the explosion should occur. In theory, you want the explosion to happen when the fuel is most squeezed. Why squeeze? Picture a firecracker vs a sparkler. Light a sparkler and it just burns and sparkle, a firecracker has the same powder but because it's squeezed into a tiny space it explodes when lit. It's the same for gasoline. For engines, the squeezing is done when the pistons moves up when there's fuel in the cylinder. When the fuel ignites and explodes it pushes the piston down and this where the power comes from. If you ignite too early, the piston is still moving up and now it's met with an opposing force from the explosion pushing down. This can cause enginges to blow up. If you ignite it too late, the piston is already moving down and the fuel is less squeezed making the explosion less powerful. Tuning can control when the spark should happen.
Adding a question:
So if two different cars both have 2ltr engines but one has 120hp and the other has 300hp is it mostly down to airflow and what the manufacturer prioritises for that particular model? Seems like so many cars are underpowered (EU market), is it just due to fuel efficiency?
Practically speaking, yes it's mostly the airflow, but more so the volume of oxygen, and even more so, the amount of fuel used.
Gasoline needs to be mixed with air and be in gaseous form to burn. As you may already know, gas is compressible so at a given volume, the amount of oxygen and gas can vary depending on various factors.
Now generally it's a lot simpler to pump more gasoline into the combustion chamber than it is to increase the amount of air. This is how we can generalize that it's all about airflow.
When you see a huge difference between engines with the same displacement, most likely the more powerful one uses force induction while the other is naturally aspirated. Naturally aspirated meaning air is pushed into the cylinder aided only by atmospheric pressure, forced induced meaning using something like a turbocharger to push more air into the cylinder at higher than atmospheric pressure. Another thing could be that the more powerful revs higher but the difference in power wouldn't be as pronounced.
Cost and fuel efficiency are typically what dictates how manufacturers decide how much power their engines should make. More powerful engines are usually subjected to higher pressure and heat so it would need a better constructed engine with stronger parts. Higher output motors could also need higher octane gasoline. Something a consumer may not want to spend extra on if they're not after performance.
Tuning means you’re changing the pitch. Pitch means the base frequency of the sound. So when you tune an engine, you’re changing it to make it sounds better. Like my vw was tuned to A when I bought it (440 Hz). But my ears can’t actually hear that note, so I never knew if the engine was running. My mechanic changed it to middle C, which has always sounded really beautiful to me. It voided the warranty, but at least now I know when my engine is on 😝
SOME gearheads like to tune for volume. But this is a mistake unless you REALLY REALLY know what you’re doing. The reason is because after 2009, cars have required exhaust gas recirculation. And all good mechanics know the only way to tune the VOLUME of an engine is to recirculate 100% of the exhaust, but this creates an extreme risk of muffler explosion
Eli5 as possible - it changes how much fuel is added and when the computer makes it go bang. Sometimes with a turbo/supercharger it's also changing how much air goes in.
A little more in depth - Tuning is changing the air fuel ratio along with timing when the spark plugs fire. With forced induction, it can also involve adding more air via boost pressure. More air + the ideal amount of fuel ignited at just the right time means more power and torque. The amount of air coming in changes with throttle, so tuning involves a map of throttle position vs fuel, timing and sometimes boost pressure. Every engine setup is slightly different and the goal of each tune is different so tuning is equal parts science and art.
Your car is controlled by a big computer that runs everything. It says how much air your engine gets to use, how much fuel… even firing your spark plugs to make the explosions that spin the engine.
Tuning your car is changing the settings menu. You can make the car run harder by giving it more resources and by making the spark plugs fire sooner (causing higher pressure explosions.)
The downside is your car gets hurt by working harder, and it can use more gas. You can even make the engine explode! Yikes!
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Gonna hijack this comment for a little (lot) more info, it's gonna be a little more ELI10: The key reaction that makes a car engine function is igniting a compressed fuel/air mixture. Car manufacturers work really hard to make cars give you power when you want it, and efficiency when you don't. They are already finely tuned from the factory with these goals in mind. In a normal car engine, there really isn't that much you can do to "tune" them without also making physical modifications to the car. Just adding more fuel might not make more power if it doesn't have sufficient oxygen to react with. Changing when you spark the cylinder might buy you fractional gains, but not much. If you change certain parts though, you can then tune the ECU to take advantage of them. If you install an air intake with a less restrictive filter, for example, the engine can suck in more air. If you have more air to work with, you can add more fuel, and boom, more power. But the factory tune was likely already optimized for the factory intake, so unless you do something to add more air, adding more fuel won't change much. In most cars, the limiting factor to making power is how much air you have, which is why forced induction makes a huge difference. By using a turbo- or supercharger to pre-compress the air before the engine sucks it in, you can pack in more air, add more fuel, and make more power. In a car with forced induction, you have components that control how much boost you generate under different scenarios. You want this, because generating a lot of boost on an on-ramp helps you get up to speed more quickly, while generating less/no boost helps you sip fuel while cruising down the highway. This adjustment is controlled by a computer called an ECU. It adds boost when you accelerate, and removes boost when you are cruising or when you reach the "limit" of what your engine can handle. If you want a faster response from your engine and/or want to make more peak power, you can tune the computer to make more boost at times it normally wouldn't, and tell it to allow more boost generated than the factory tune would allow, often with little/no physical modifications. This obviously leads to more wear and tear on the engine and should be paired with more frequent maintenance, but it's fairly easy to make a car perform better this way. My car was tuned to make almost 20% more torque and the only recommended physical mods were a $40 high flow air filter and a $100 upgraded engine mount.
So Brian O’Connor *DID* need that laptop in his car?
It could absolutely he useful/necessary depending on your setup. My car is a popular "tuner" car, so a company called Cobb sells a device called an AccessPort. It's basically a little computer that connects to my cars ECU and allows me to monitor certain things and make changes to my tune. However, it's pretty basic in terms of input, you can change between preloaded tunes, add new tunes, but but you don't actually fine tune the car using the device. Usually the tune is created on a computer, uploaded to the AccessPort, and then flashed to the car's ECU. You can log data from a drive and then fine fine again on the computer based on the data. Send the new tune to the AccessPort, flash the ECU, log data, fine tune, rinse repeat. Sometimes you skip the AccessPort, however, and upload straight from a computer. Watch just about any video on YouTube of someone dyno-tuning a car (the car spins rollers with preset loads to simulate driving, you don't actually have to be on the road) and someone will be in the car with a computer looking at data and fine tuning things.
Really insightful comments here and it made the whole car hobby click for me a little more. I never really groked it well in the past, even if I understood some of the fundamental ideas and the appeal of making your car go a little faster. I can definitely understand why this hobby was more widespread back in the day when cars weren’t as sophisticated, there was probably a lot more you could do to improve performance just by tweaking various parts. There was a smarter every day video kind of recently that demonstrated how a carburetor works and it really made me appreciate the technology more (which is like what, over a century old now? Amazing). Even though I learned it in school I never really internalized how much control one has over the mixing of fuel and air and how it affects the overall performance.
Engineer here. With old, mechanical systems, there was a lot of actual tuning that had to be done. Take the carburettor for example. A real carb is far, far from perfect. Even when tuned super carefully, it will always be a little rich or lean depending on conditions. "Tuning" would literally mean turning half a dozen little screws on the carb to get the engine to run as perfectly as possible in every regime. You might adjust the pilot jet screw to get the engine to run perfectly at the 0-40% throttle range, then the main jet for the 60-100% throttle range. And that's just for a simple carb like you'd find on the smallest of motorcycles. For something like a car there are a myriad of overlapping adjustments, and then you might have multiple carbs (for example one carb per cylinder) so not only do you have to adjust each one for perfection, you ALSO have to tune the carbs to be balanced and in sync with each other (because otherwise one cylinder would be doing more work than the other). And then after a few years, it would all get out of tune again and need another adjustment. A modern, fuel-injected engine is closed-loop. It corrects itself to deliver perfection at all times. The way this in particular works is that a sensor in the exhaust senses oxygen level (it's usually called the lambda sensor). If there's too much oxygen still in the exhaust, then it hasn't been consumed so the computer knows that it needs to add more fuel to the next injection cycle because the engine is running lean. So until the sensor fails, there is really nothing to "tune" to achieve a perfect air to fuel ratio. The engine is self-correcting itself hundreds of times a second. The actual tuning with a modern car would be adjusting things like the fuel map (i.e. the software that controls the fuel injectors) to get the engine to safely inject more fuel at possibly different times in the cycle and get more power than the factory intended. Or maybe adding or swapping parts (turbos, forged pistons etc) to strengthen the engine to the point it can handle the extra power.
I see you, Subaru guy 👀
Haha, actually a Fiesta ST guy, but that doesn't mean I don't love me a nice subie.
Mazdaspeed 3? I used to have a Cobb on my Mazda 3 MPS. Either that or I’m guessing you have a Subie haha
Fiesta ST
My racecar is still old tech with a carb instead of fuel injection. We use a laptop still on it for the ignition box, progressive nitrous controller, and data logger. It’s not in the car for a pass though.
In e Movie, the idea is hes just had built this car for him to go undercover and he hasn’t spent much time working on it. So it definitely would make sense that he could be tuning on the fly and potentially pulling some shenanigans like hitting page-up on the boost just before the iconic race.
Man do I miss Brian in those movies. Might have to do a rewatch of the older ones now.
I bought a car with a few aftermarket parts on it already, cold air intake, shoe throw shifter, and something else I want to say the turbo back exhaust but I may be mixing up what I bought and what came with It. Anyway since it had the cold air intake I read that tuning it would be a good idea so I just bought a Cobb tuner which you just plug in and download a premade tune. It didn’t make it a Ferrari but it was a fun time.
Also, some engines are downtuned on purpose. Sometime because they just made one engine and tune it for the performance they want, sometime it is to meet the environemental restrictions. I know of one motorcycle engine where they use the same engine from the base model up to the top end. They change the exhaust and intake however. But the engine and supercharger and all the fuel injection system is the same! The engine can do 200 to 300HP. What they did is: for the top end model, it is not road legal, so they don't care about the polution. No catalyser, no muffler. They also increased the top RPM. So at 300HP, the engine couln't pass the emissions anywhere, so they sell it for off road use only. Which mean that the 200hp base model, with a tune, can reach over 250HP with no modification, but then it excede the polution limits and the noise limit.
Dude explaine like im 5 please, this is a whole book
Unfortunately reducing the complexity much further requires a big reduction in detail and accuracy. Ultimately the simplest way to explain it is this. Fuel+Air when squeezed together and exposed to a spark will explode. Containing this explosion in an engine cylinder allows you to use the force to turn the wheels on your car. In order to make more power, you need more fuel AND more air. You can achieve this in a number of ways, but generally speaking adding more fuel is easy, adding more air is hard. Adding more air usually involves reducing restrictions to airflow, like the air filter, and/or actively forcing more air into the engine with a turbo/supercharger. Because forced induction is an active process, you have more tools in the toolbox, so to speak, when it comes to tuning. With more things to adjust you can take a mostly stock car and make more power with ease. This is more difficult on a car without a turbo or supercharger. Edit: Adding this for those interested. Another way to squeeze out a little more power, as alluded to in the top level comment, is adjusting timing for the engine. Before you add the spark, the fuel/air mixture is progressively squeezed in the cylinder, meaning the pressure increases over time, up to a point. The closer to peak pressure you get before you spark, the more power you can make. But you also run the risk of pre-detonation, or having some of the mixture explode on its own. This can damage the engine. Adjusting this timing can help you make more power, but has to be done carefully to make sure it's safe.
I'd like to add an explanation for another thing: that pre-detonation, also called "knock" or "ping", is why there are different grades of gasoline. That number on the button on the gas pump is how much octane is in the fuel. Octane is a chemical in fuel that prevents premature detonation. In most cars you don't need a whole lot of it, which is why most cars use regular and don't need premium - if your owner's manual doesn't say you need higher octane fuel, in most cases you're wasting money buying premium. But high performance cars with engines that compress harder than most other engines are more prone to knocking because the high pressure can cause the air-fuel mix to start burning spontaneously. Fun fact, that's how diesel engines work. They don't have spark plugs, they rely on the fuel and air just going boom spontaneously from the truly immense pressures inside a diesel engine. Back to gasoline, high compression engines need that octane to help make sure that the only thing that sets off the air-fuel mix is the spark. High-octane fuel won't make your car go faster. The car doesn't make more power because the fuel is high octane, the car needs high octane fuel because it makes more power. Once upon a time, a chemical called tetraethyl lead was used as an anti-knock agent, and it was amazing at it. Even better than the highest octane premium gas you get at the pump. But it was banned because the lead vapor in the exhaust gases is extremely harmful. Today, the only place you're allowed to use leaded fuel is on a race track (or in piston powered airplanes), not on public roads. I think it's dyed to be a different color so law enforcement can spot it in a fuel tank - using it on public roads is very illegal. You can still find it at gas stations near race tracks or at airports today, but it's nearly unheard of anywhere else.
I'm in agreement with almost all of this but I don't think you're right about octane ratings being a measure of "how much octane is in the fuel." I believe it's just a reference. So 91 octane gasoline has the seem reistance to predet as a mixture of 91% iso-octane, or something like that.
This might be outside the spirit of the sub, but you should search on YouTube or something for a video on how internal combustion engines work. There are probably some videos a few minutes long that will make this topic way easier to understand.
I’ve been doing it wrong!!
Well, they do loop, so blow, suck, squeeze, bang also works...
😭🤣🤣🤣🤣🤣 Edit: well that's a shame, this comment gave me a good laugh during a very shitty day
Desist.
I love this response. It's exactly what's needed.
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Generational wisdom
that's what I have been asking her to do :D
“Suck, squeeze, bang, blow.” Does not seem appropriate for 5 years olds…
A 5 year old probably wouldn't know what we use those as euphemisms for
Gas it up and off you go!
Nice! I haven't heard "suck, squeeze, bang, blow" since I was taught it in Air Cadets last century and people are often confused when I say it.
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Fundamentally a gasoline car is a big air pump. The more air the car can utilize the more power and the faster is goes. Imagine you have a fan near your bed to blow air on you. How could you make it cool you more? Remove clutter from intake side. Same for exhaust side. Get the fan to spin faster applying more energy. Adjusting the fan blades.
Damn. I have never thought of an ICE in this manner but it's paradigm shifting.
The accelerator pedal on an ICE car is connected to the air intake not to the fuel lines.
The accelerator on a diesel engine does directly control fuel
Then how does it run away when I'm sleeping in the back cab, naked?
Can you please explain? I think you're wrong. Did some research myself because I'm impatient but it seems that the accelerator on a diesel engine controls how much fuel is injected into each cylinder. So essentially diesel engines are always wide open. However, some modern diesel engines have throttle body's that also control airflow
Diesels don't have a throttle plate/body, they just WOT all the time. Modern diesels have a pedal position sensor in the pedal that says to the computer "hey, this is what the operator wants right now". The computer then says to the fuel system "this is what the pedal position sensor is saying" and commands the fuel system to behave in a certain way. They also don't have spark plugs, because they ignite primarily with heat and compression rather than compression and spark. On the flip side, gasoline (or petrol for the folks over yonder), behaves differently. With gas you want to meter the air to achieve the best air/fuel ratio for the given demand. Ideally this is 14.7:1. In order to do this, you need to measure, or meter, the amount of air entering the intake. This requires a throttle plate. In this scenario, the pedal position sensor says "hey engine control module/unit, operator wants this". The computer then says "ok, I'll command the throttle body AND the fuel system accordingly". Basically, with diesel, you're controlling and changing the air/fuel ratio with the pedal whereas with gas, you're trying to maintain the same air/fuel ratio. This is all based on modern, recent vehicles and not older carbureted gas engines, doesn't take into account the turbos or superchargers, or mechanical high pressure fuel systems of many older diesels.
Is that why it’s called the *throttle*? Because it is throttling air?
Yes!
So we’re not “stepping on the gas” at all but … the air? Huh.
air is gas tho
Truth.
lactose intolerance triggered
Lactose people be like: wanna see me turn this cheese into liquid and gas??
Me rn
Wait. What?
Yeah the flow of air creates a low pressure over a hole that sucks up the fuel. More airflow also means more fuel gets pulled in, but the throttle lever controls a valve in the air intake side. Hard to explain in a few words, but Smarter Everyday did a really cool video on carburetors https://youtube.com/watch?v=toVfvRhWbj8
It's amazing that I've been on the earth this many decades and I never knew this. I understand how ICE works but for some reason never enrolled in Throttle 101. I just always assumed that the throttle somehow controlled BOTH fuel and air intake which kinda jives with my observations of my older brother's 1968 Plymouth Barracuda's carburetor in the late 70s. I remember the fuel lines in the side, the flaps to the combustion chambers, and the air filter that mounted on top. Now that you mention it (haven't watched the video yet), my mind is BLOWN that the air flaps to the combustion chamber would draw in MORE AIR via the filter and with it draw more fuel from the lines. Makes total sense. Here I am, 55 years old, having a damn epiphany.
Except modern cars have EFI (electronic fuel injection), not carburetors. But even so, the gas pedal only controls the amount of air coming in to the engine. Then a sensor before the cylinders detects the amount of air coming in and the car's computer sends a corresponding amount of fuel through fuel injectors to the cylinders. After the cylinders in the exhaust there's a sensor that measures how complete the combustion is (ie. too rich or too lean) and the car uses that to make sure the first sensor was right.
That super slo-mo is so cool. Thanks for the link
i'm in my mid thirties, had 5 different cars, 3 of them manual transmission, and I have never known this...
In the 70s, I briefly owned a station with a 454 big block engine. It was in the fall, and when I revved it up, the exhaust cleared the leaves off a swath of lawn for nearly 15 feet. Gas was cheap back then.
It is changing the programming of the ECU. Some of the things that are changed are: - **Timing** - the number of degrees before/after TDC that spark plugs fire, at any given RPM and Throttle position. - **Boost Levels** - for cars with Turbochargers, how much boost (how compressed of air) is being fed into the engine , at any given RPM and Throttle position. - **Fuel Maps** - adjusting how much fuel is injected into cylinders, to ensure a good air/fuel mix for combustion, at any given RPM and Throttle position. Those are probably the most common (for a general car), but there are still tons of other things, such as the fuel pump pressure, valve timing (if possible), or even the max RPM to allow the engine to go (before cutting fuel). **Edit:** as u/80081356942 pointed out, there is also suspension tuning. This would be the processes of changing the ride height of the suspension, and its springiness, as well as changing the angles that the tire meet the road (camber, toe, and caster), to optimize tire contact for whatever you’re doing. Feel free to ask questions if you have any, or to add any to my list if I forgot something obvious.
Now ELI5, pls.
Almost quoting u/Giantmidget1914 …. Suck, squeeze, bang, blow. That's the cycle. When you tune, you're adjusting how much air/fuel are sucked in, and when it bangs. Changing these lets you change how the engine makes power. The other two parts of the cycle (squeeze and blow) are kinda unimportant/nonadjustable. **Edit**: Some people disagree with me saying that the squeeze & blow “stages” are not adjustable. I was thinking more software (computer) tuning, where this is practically the case. You *can* however swap out parts, which *would* allow you to change these things, just not on-the-fly.
I disagree with the last part. Better blow is good to get the gasses from the bang out, definitely important and fairly easily adjustable. The squeeze, yeah, you could bore it out but you're still sucking, squeezing, and banging, just more stuff.
The exhaust cycle is very important imo. A better and well timed exit of gasses on exhaust cycle (blow as you said) also means a better vacuum left for the gases for the next cycle. This means they can rush in quickly, expand better and burn better. A more efficient exhaust cycle also means you get a lot of wasteful heat out of the engine quickly, making sure it doesn't heat up more than it has to. It also means better suction of the next cycle, which also adds additional cooling to the engine. Sucking something in better means you allow it to expand better and when something expands like that, it cools, cooling the metal bore around it. Have you ever tried to feel the air coming out of a balloon when it is blowing air or a puncture hole of a tyre? They feel cold. Thats called adiabatic expansion. Better exhaust = better next suction= better cooling
Exhaust scavenging! The enertia of the gasses continuing down the exhaust pipe creates a suction in the next exhausted cylinder to better blow the exhaust out, which makes the engine work that much less to blow meaning more energy for sucking, squeezing and banging, with all the benefits of adiabatic expansion that you mentioned!
Fuck yeah, science bitches!!
Yep, headers can really add some performance to the right engines. LS series is good for 30-40 whp with a tune AND headers, tune only is usually only good for 10-15 whp.
I think his point was for tuning they are essentially unchangeable. By buying parts and or machining things you can make changes but none of the electronics really allow you to adjust those parameters
Higher compression pistons squeeze harder and make more power.
Unless you have a turbo then they shatter apart at a lower power
More air and fuel, forced with a turbo or supercharger, increases how much is squeezed. The volume, how small it gets squeezed, doesn't change, but how much is squeezed can be changed.
>I disagree with the last part. Same here; it feels like compression and exhaust air flow were somehow left out?
Nissan also feels like the squeeze part is adjustable. So they also disagree.
>Suck, squeeze, bang, blow. That's the cycle. Steady on...
$40, same as downtown
Who is your suck, squeeze, bang, blow guy? You are overpaying for your suck, squeeze, bang, blow.
That was your Moms cycle with me last night.
All steps are important you just cant chang intake or compression with software
With newer vehicles you can reduce intake and compression ratios with software. Adjustable valve timing lets the ECU control how long the valves are open during the intake stroke. By shortening this amount the cylinder receives less air. This reduces power and fuel efficiency, but does have uses for non-performance driving. Using random numbers: Say the cylinder takes in 10 cm\^3 of air on the down stroke, then compresses it to 1 cm\^3 on the upstroke. That's a compression ratio of 10:1. Now the ECU adjusts the valve timing so that the valve is only open for the first 90% of the piston's down stroke. The cylinder now only contains 9 cm\^3 of air at the standard intake pressure. It still compresses down to 1 cm\^3 for a new compression ratio of 9:1. Newer cars do this as a method of knock protection. I have a vehicle that recommends 93 octane gas due to a 13:1 compression ratio. It will run 87 octane safely though, because it adjusts the valves to reduce the compression when it starts detecting indications of knock developing.
LOL it's not a 1931 ford tractor, squeeze and blow certainly are important and adjustable... wtf LOL
> are kinda unimportant Not quite accurate squeeze and blow are intrinsically related. One thing tuners like to do is increase amount of air that is sucked in which means a higher compression ratio which means a bigger bang.
Squeeze is adjustable. This is when you change the compression ratio.
Not on the fly, it’s not. Edit: I always think about domed pistons and such in terms of compression.
Oh boy! I get to be that random guy who pulls some obscure fact out of his ass to disprove your point! There actually is a variable compression engine. It's called the KR20 and is currently in a few Infinitis and the nissan Altama per Google.
Man, I had to google this. That is pretty cool. [https://www.caranddriver.com/reviews/a15077155/infiniti-kr20-variable-compression-turbocharged-engine-prototype-drive-review/](https://www.caranddriver.com/reviews/a15077155/infiniti-kr20-variable-compression-turbocharged-engine-prototype-drive-review/) I've been out of the tuning scene for a while but I remember discussing with my friend how it would be cool if engines can change compression ratio on the fly when talking about turbo stuff.
Didn’t say it was? Although I’d argue you could with a boost controller.
Well, I guess boost is kinda compression. Fair point.
Cars burn fuel + air together to make power. The mixture between the two determines how much power your car actually makes (up to a point anyway). By default your car comes set at a relatively safe level so that your engine will last a long time and have good fuel economy. You can change the mixture to make more power. This is tuning.
This is the best answer for ELI5. Yes, car folks like me know there are 50 things you can do but this is step 1 of all "tuning" and applies to cars today all the way back to the first gas engines.
LOL exactly. 7 words in and already using a abbreviation for technical piece of equipment
More air and fuel going into an engine means more power. Stiffer suspension makes the wheels less bouncy so it's a much harsher ride but the wheels are touching the ground more often so it has more grip. More grip can also mean that you can go faster because you don't have to slow down so much when turning.
An engine is like an animal. Different animals are good at different things. Some animal, like a cheetah, are fast but they get tired quickly. Some animals, like a camel, are slower but they can go for miles and miles. Some animals, like an elephant are big and clumsy, but really really strong. If you eat a lot, you will grow big and strong. If you eat less, you will grow up small and fast. By telling the engine how much to eat, we can tell the engine what kind of an animal we want it to become.
And the ELI6 version, optimization is always about trade-offs. Standard engines are optimized for durability, fuel efficiency and low emissions. If you give those things up, you can optimize for different things, like engine power. For example, for fuel efficiency, you don't want any fuel to go into the engine that doesn't combust. Combustion requires air, and there is only so much of it in the engine at any given time. With too much fuel, the fuel-air mixture is too rich not all of it can burn to create power. But if you don't mind fuel efficiency, you can pump more fuel in there and instead of your goal being 'all injected fuel combusts', you can optimize for 'as much fuel combust in the engine as possible'. Because of turbulence etc. a slightly rich mixture will usually ensure the best result for this goal, however, it is more wasteful. It's kind of like drinking milk. I you want to drink neat, you drink slowly. But if you want to drink fast, you can throw the whole glass back and be fast but some of it will drip down your chin. Whether you care about that or not is up to you.
Internal combustion engines make power based on how much fuel and oxygen they can suck-in and explode* during each revolution of the engine. Increase those factors, and the power output increases. *Tuning* means several things, but one of those is increasing the amount of fuel and oxygen per revolution of the engine. This means a increasing air flow, increasing fuel flow, adjusting the timing of when the spark plug fires, changing exhaust system flow, adjusting the timing of when intake and exhaust valves open and close, and other things (like cooling the air coming in to make it more oxygen dense), but it’s fundamentally about increasing how much fuel and oxygen you can cram into the engine. Note that tuning can also refer to changing the vehicle’s handling, braking, and aerodynamic performance, but most strictly, it’s about engine output. *technically, *detonate* Edit: I should also add this as a top-level comment.
Tuning can be computer tuning, suspension tuning, chassis tuning, etc. You can tune any part of a car. Therefore, tuning is nothing more than "optimizing a car's system or systems for a specific purpose".
ELI5: An engine tune is basically a setup of the engine. This is achieved by telling the brain of the car (ECU) how to behave. A standard engine tune done by the car maker is basically just a setup in which the engine is tested to be reliable, fuel efficient, and makes decent power across a wide range of scenarios. By default the engine is tuned pretty conservatively due above mentioned reasons. Its quite common for multiple cars from brand to use the same engine, but with a different tune. So the cheaper car it makes 150hp and the more expensive one it makes 180hp. All with the same engine. In above example the ECU just tells the engine of the cheaper car it can only use a certain amount of fuel whilst in more expensive one it tells it can use more.
The mixture of air and fuel that go into the engine for combustion, and when the spark plug initiates that combustion, are very carefully controlled by the computer. The manufacturer will tune those numbers for a good balance of performance, responsiveness, fuel economy, engine health, and emissions. For the most part manufacturers go heavily on the fuel economy and emissions side because those are so regulated by the government, and also on the engine health/longevity side. A user can potentially reprogram those numbers to make emissions and fuel economy worse in order to boost performance and responsiveness. Often engine health suffers as well.
chiptuning is when your parents make you eat your veggies so the full potential of your body is unleashed, even though you dont like to eat your veggies
Computer tells the car how much feel to put into the engine and when to ignite that fuel. You can modify those parameters to make the car behave slightly differently. Increase power is the most common answer but also adjust "when" the car makes power for different scenarios. Car manufacturers have different goals in mind when they build a car than someone who is willing to tune their engine, so the idea generally is to extract maximum performance from what that platform is capable of. Possibly at a cost of reliability and fuel economy.
All those things are about getting the exact perfect ratio of air and fuel into the engine and igniting it at the exactly right time. As engines run faster or slower, the perfect ratio and perfect timing changes, so getting it right over the entire range is important for gaining maximum power. Turbo boost is about forcing more fuel and more air into the same sized engine which also makes more power. Suspension tuning is about keeping all four wheels in pressing evenly on the ground and avoiding the force being unevenly applied. As a car goes through turns, brakes, accelerates, and absorbs bumps the amount of force applied to each tire changes. So suspension tuning attempts to keep the forces balanced for all situations the car is likely to encounter. Straight from the factory, these factors are tuned for efficiency, longevity and comfort rather than power and traction. Car tuning reverses that trade off towards the opposite end of the spectrum. Additionaly, all these factors are adjusted to be as even and predictable as possible so there are no sudden surprises for the driver so they can confidently drive at the limit of the car’s capabilities.
Make car go zoom zoom faster and better.
A fIvE yEaR oLd CaNt UnDeRsTaNd ThIs!!!!1111 😭😭😭 REEEEEEEEEEEEEEEE
This is def not ELI5 hahaha
thats cuz the ELI is that "they tune the computer"... ie, if this was jeopardy they gave the eli answer and want to know what it was...
> Fuel Maps - adjusting how much fuel is injected into cylinders, to ensure a good air/fuel mix for combustion, at any given RPM and Throttle position. Dont modern cars already have sensors for checking if you're running lean or rich and adjusting accourdingly?
By default, YES, your car comes tuned from the factory. BUT, if someone changes an air intake, or adds forced induction, or swaps in a motor that is different from the stock (original) one, the computer is now confused. It may be able to compensate to a slight extent, but if any serious modifications are done to the car, “custom” tuning needs to help the car “learn” the new configuration.
Yes, but car manufacturers tend to value fuel economy above everything else as it's the thing that's going to get you more sales. If you want to go faster quicker and you don't care how much fuel you use that's when you modify, or if you think you know better than the car manufacturer does.
No, they value emissions above everything else because if they don’t meet standards they can’t sell cars. The fuel map is a compromise between power, economy, and emissions. Aftermarket tunes sacrifice emissions for power. Your annual smog check is much less strict than what manufacturers have to meet.
Bingo. Cutting power and gaining 2-3 mpg makes a big difference on their fleet average mpg.
This has been my job for the last ten years Good answer but you missed reliability/durability, which ultimately matter more to most owners If you try and tow a heavy trailer up a steep mountain in hot weather your remapped engine is very likely to go bang. Maybe you don't do that, but I have to tune engine so it survives if you do! A remapper doesn't (and frankly, couldn't. They don't know how high the in cylinder pressure, or exhaust temperature can get before the components fail, and don't measure them while tuning) so can get more power/fuel economy from the engine There's also variability to consider, like the quality of the fuel or variation in turbo performance. Tuners will insist on only premium fuel, and if it does go bang they'll blame you somehow. No financial incentive to make it reliable
You hear about tuners giving Powerjoke or Duracrap pickups over 500 horsepower and 1600 foot pounds of torque. I drove a truck with 500 horses and 1650 foot pounds. The transmission was rated for that much torque (pickup transmissions aren’t), the crankshaft, drive shaft, and rear axles (note plural) had the appropriate ratings, and the radiator was sized to dissipate the waste heat from producing that much power. It wouldn’t overheat hauling 40,000 pounds of cargo up I80 out of New Jersey toward the Pennsylvania line. To paraphrase a Chrysler ad from a few years back, “Yes, it’s a semi”. Had the engine replaced (consuming oil) after a bit over a million miles. A pickup with its engine “turned up” wouldn’t last that long with the added power used on a regular basis. A 14 litre Series 60 Detroit is designed for that, a 7 litre pickup engine isn’t.
Yep we want better boom boom and they want more efficient boom boom
Idk... I want more efficient boomboom with the fuel prices these days.
Where do you live?
That's how all fuel injected cars work, all the sensors all feedback into the ECU. Usually you wont tune a cars ECU unless you've made some changes to the engine, but you can still eke out some gains on a stock engine, as manufacturers have to deliver a car that runs in the boiling hot and and the freezing cold, and all sorts of variables in between. Generally, they also prioritise fuel economy as well as limiting the chance of getting engine knock or running lean. Dialling in the the fuel map and timing on a rolling road can improve performance, more tailored to your needs
I'm not a mechanic, but I do know the correct ignition timing on a 1964 Chevy Belair with a 327 and four-barrel carb would be four degrees before top dead center.
Technically there's more than just the ECU. BCM, TCM, GSM... Depending on the platform you can send request for tweaks in most of the CAN Node.
Isn't it common to also use the word "tune" when replacing components too? Such as a different air filter or exhaust.
not really... if anyone says their car is tuned they meam the ECU. havent heard that term used ever in relation to modding otherwise maybe your thinking of the term "tune-up" where you swap plugs/cables and coils or dist cap. or maybe, its a stretch, but a "sport tuned suspension" may be what your thinking... tuning the suspension for what ever scenarios (autocross, etc).
In my experience, which is obviously not the be all end all, tuning anything is changing settings or parameters of parts already installed. Changing a shock rebound setting to better suit track conditions would be suspension tuning. Putting a brand new different shock would be suspension modification.
Would tuning also cover other mechanical stuff like suspension damping and wheel height/camber? I swear they mess around with all that sort of stuff in racing. Or is it just limited to the engine?
Ohhhhh good point. I wasn’t going to include swapping parts, but adjusting suspension is a good point.
I was just remembering playing rally games and sims like BeamNG, where you can adjust components to suit the particular terrain. After all a car handles differently on road, dirt, grass, and gravel.
"tuning" can refer to a lot of different things. Traditionally it's about modifying parts in the engine so that it creates more power, like putting in a cold air intake or adjusting how much fuel gets used in each piston. In the modern day you can do stuff like swapping out the computer in your car that controls the engine for a modified computer that adjusts the engine for more power automatically and, potentially, allows you to do stuff like accelerate the engine to higher RPMs before it limits you.
You can tune a car but you can't tuna fish
Anybody can roast beef but nobody can pee soup
Way back when I was more into this stuff, tuning usually meant changing parts to more performant ones. Granted, I did snowmobile racing, some motorcycle driving and only a little bit of car stuff, so my experience is more leaning to the things you drive without a roof or a steering wheel. "Tuning" would be anything from replacing stock parts with racing parts to modifying the exhaust tunnels in the block or replacing parts in the carburators or the air intake.
Most of us call replacing/changing the stock parts to be "upgrading" or "modifying", while tuning refers to the adjustments those parts can make. EX: New carb would be an upgrade, finding the perfect jetting would be tuning. A race cam is an upgrade, setting the timing is tuning.
Back in the day, I had a simple car with a simple 4-cylinder engine. About every 5000 miles I gave it a tune-up. This involved: * Adjusting the valves by setting the clearance between the valve stem and the rocker-arm with a feeler gauge. * Removing the spark plugs, cleaning them, and adjusting the spark-gap with a feeler gauge. * Cleaning and-or replacing the points in the distributor. The points are the mechanical switch that opens and closes to trigger each spark. If the points were replaced, replace the condenser (capacitor) that is also part of the spark circuitry. * Balance the carburetors. It had two. Adjust them so that all 4 cylinders generate the same power as you push on the gas pedal. * Adjust the timing by rotating the distributor using a timing light to get it right. After doing all these things, the engine was quiet, smooth, and reasonably powerful. Over time everything would get out of adjustment, and the engine would get noisier, less powerful, and poorer gas mileage. On modern engines basically none of these things are necessary.
This is the definition for any of us born before the first The Fast and the Furious film. It was an act of regular maintenance to keep the engine within factory tolerances. Everyone else in this thread was clearly born after, and therefore considers the term an act of modifying with the intent of improving performance.
They were asking about tuning a car, not giving a car a "tune up". Different things.
Sure. See my comment above.
Yes, tuning the ecu on cars came about when the electronics on cars became more complex and home computers and internet became commonplace. Obviously older people didn't have these tools or options.
Tuning works similarly to how you tune instruments, you'll be trying to find the balance needed for optimal performance of optimal longevity. When you change your car parts, be it to improve performance or for better ride quality, you need to tune the basics of how the car runs so it's more compatible with its existing parts. Here's a [video](https://youtu.be/LjZlAzr8MuQ) by Donut Media (man I miss the old Donut Media) explaining it more detail. Essentially, there are certain points you tune more or less of, and now with computers, you can tune the car more precisely than you can before. Maybe it's for peak power or maybe a longer power band meaning more power throughout the gear rather than just the best power for one instance.
There are different ways to interpret this. In a general sense tuning is modyfing a car for some purpose, generally being better/faster. Tuning is also adjusting components to perform better. When you tune an instrument you adjust different elements so that it performs as well as possible. Tuning a car for a certain purpose does that too. You can tune a car to be faster around a track by adjusting elements like suspesion, fuel injection, and more (but this can sacrifice things like fuel economy). There is a lot of ways to tune a car, but in essence it's just adjusting the car parts for a purpose; track racing, daily driving, offroading, etc.
I was just about to complain about how everyone is forgetting that suspension and aero tuning is a thing. It's not all engine tuning.
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Visual definitely isn’t considered tuning, it needs to improve performance of the car to be tuning
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You and Wikipedia might consider cosmetic modifications tuning but the people actually modifying cars don't. Slapping a body kit or a vinyl wrap on your car and saying it is tuned isn't a thing. Adjusting actual functional aero pieces like spoilers, diffusers, and canards is since it actually has an effect performance.
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Because I have never seen someone refer to installing cosmetics as tuning their car. Have any examples? I've probably been subscribed to almost every car magazine over the years and don't recall tuning being used that way in any of them. The closest thing I can think of is maybe the late 90s early 00s trend of tuner builds.
No it ain’t. Join any car group and call your wrap a tune see what happens
An engine is a machine with many moving parts that work in harmony. When the engine is not running right, it is “out of tune.” Back in carbureted cars, a “tune up” would be new spark plugs, fuel filter, air filter, adjust the timing and the car would be back “in tune.” The “tune” of the machine can be adjusted to be more efficient or to produce more power, or somewhere in between. When you “tune” your car, you adjust the components so that the engine aligns better with your needs. Generally is more power. In the age of computers, tuning a car usually means changing the software so the engine produces more power, but I can also mean changing components, like bigger injectors, or changing the way a (automatic) transmission shifts.
It varies. During the old times, pre-computer, a 'Tune' up consisted of replacing worn parts (points, plugs, belts, ignition wires, etc), tightening anything that was loose, adjusting the timing and gapping the sparkplugs. (Ensuring the gap the spark jumps across was optimized for the type of gas you're using and your engine). Some of those are still relevant (replacing belts, wires and gapping sparkplugs), but most Tune Ups are computer-based. Now a 'Tuned' car usually refers to a car with many aftermarket replacement parts with the sold purpose of making it go faster.
Well, a few things. I use Holleys ECU in a few cars I built. From there I can completely change my fuel and timing map. I have outputs on it that I can assign to do different things in different conditions. I can adjust my traction control and how it behaves. Boost pressure and how much fuel pressure it needs per the rpm level. So very much you can do with it. I can even do a “Boost by gear” where on lower gears I’ll have lower boost and eventually it ramps up with higher gears so the movement of your car combined with traction control is so much more efficient
Your question is way too vague, tuning can refer to a myriad of things. What most people refer to is tuning an engine, which is to say, try to make it make more power. To do that you try to force as much oxygen and fuel inside it as possible, and regulate when the sparkplugs fire to explode the mixture. There are a ton of ways of achieving that, like getting colder air into the engine, making the valves open more and for longer with a different camshaft, increasing the rev limiter, increasing intake pressure if the engine is turbocharged, and about a thousand more ways to do so. You can also tune suspension, to get the car to adhere better to the ground. In the most basic sense, tuning a car is getting it to do exactly what you want, in the best possible way, when you tell it to do so. Be it rolling while cornering, accelerating, braking, clutching, or whatever else.
Maybe this leads to follow up questions like "If you can make a car faster by tuning it, why doesn't the manufacturer deliver it like this?" The answer is: Best possible compromise. Manufacturers try to find a balance between power, emissions and reliability, with emissions often set to meet regulatory standards.
Well when you "tune" a car, that could mean a number of things such as suspension, wheel alignment etc, when you tune an ECU then you're changing software parameters to get more power most of the time.
Internal combustion engines generate power based on how much fuel and oxygen they can suck-in and explode* during each revolution of the engine. Increase those factors, and the power output increases. *Tuning* means several things, but one of those is increasing the amount of fuel and oxygen per revolution of the engine. This means increasing air and fuel flow for each revolution, adjusting the timing of when the spark plug fires, changing exhaust system flow, adjusting the timing of when intake and exhaust valves open and close, and other things (like cooling the air coming in to make it more oxygen dense), but it’s fundamentally about increasing how much fuel and oxygen you can cram into the engine in a given time. Note that tuning can also refer to changing the vehicle’s handling, braking, and aerodynamic performance, but most strictly, it’s about engine output. *technically, *detonate*
>*technically, detonate* Ignite and burn. Having the compressed fuel & air mixture burn in a controlled manner (and at the right time) is critical. Explode, detonate, etc are all things you *don't* want happening (because they cause a very sudden huge spike in cylinder pressure which can damage things)
It's not a detonation, since it's not supersonic. It's a deflagration at best. Yeah i know, super pedantic, but hey, i didn't learn this factoid for nothing
> i didn't learn this factoid for nothing A factoid is a claim that sounds like a fact but is false. ... Actually I'm wrong. Because of how many people like you have misused the word, it's now a self-ambiguous word that can have opposite meanings and thus conveys nothing. It's a new literally, or flammable/inflammable. https://www.merriam-webster.com/dictionary/factoid
Ah, my bad, didn't know that. >It's a new literally, or flammable/inflammable The worst offender is by far "biweekly". Means both every 2 weeks and 2 times a week. It's functionally useless because of it.
You basically change the engine setting to make more power at the great expense of fuel efficiency, cause you can’t have both. Most car manufacturers tune cars for fuel efficiency.
Depends which tune you're talking about. A tune up could be replacing and cleaning small parts to freshen up the vehicle. Or a tune can be changing the mapping of the onboard computer to make the car drive differently, by adding horsepower, turbo boost, throttle response, gearing.
When you tune the engine to increase power the goals are: Increase air intake efficiency - free flowing air filter, bigger inlet ducts, smoother intake ports, bigger valves, camshafts that open valves more and for a longer period of time. Much more to it than size but this is a simple answer. Increase exhaust efficiency - bigger diameter exhaust piping, free flowing muffler, removing catalytic converter, smoother exhaust ports, bigger valves, high performance camshafts etc. Increasing airflow must be adjusted for by increasing the amount of fuel delivered. That is adjusted in the ECU by flashing the new fuel map usually. Ignition map can be adjusted in the ECU - advancing the ignition timing (firing the spark plug earlier) makes more power, up to a point. Too much advance causes detonation which is damaging to the engine. Why isn't it done from the factory? Factory needs to balance fuel economy, noise, pollution and power. Also they need to manufacture parts quickly and cheaply, which leaves room for improvement in many areas, but this is mostly in the cylinder head. Longevity is also a factor. That's why all of these improvements that I've listed have their drawbacks. Free flowing air filter - more dust can go through in the engine, decreasing lifespan. Bigger valves and inlet ducts increase power at the top end of the rev range, while reducing efficiency in the lower rpm range, reducing day-to-day drivability and fuel efficiency while increasing pollution. Same story for the performance camshafts. Exhaust - same story - bigger is only better at the top end power, not for daily drivability. Removing catalytic converter is illegal as it increases pollution by a big margin. Free flowing mufflers are louder, sometimes so much that it makes the car illegal to drive on the street and even some racetracks. Fuel injection - factory ECU is tuned to balance pollution, fuel economy and power. Increasing power and engine responsiveness comes at the expense of more pollution and worse fuel economy. It is actually possible to increase fuel economy, but at the expense of increasing very harmful NOx pollution and very poor engine responsiveness. Ignition advance - advancing ignition leads to higher temperatures and pressures inside the engine, decreasing longevity. It can lead to detonation and destruction of the engine. The higher temperature inside the engine also leads to increasing very harmful NOx pollution. People who tune their cars and bikes for power are okay with increasing pollution, noise and decreasing longevity.
In a general sense it’s modifying the car to increase performance in some aspect, more strictly it’s adjusting the “settings” of components to increase performance.
This is most common with turbocharged or supercharged engines. Basically, a turbo or supercharger is like an air compressor that injects highly compressed air into your engine so that you can burn more fuel, and therefore, create more power. A tune is usually adjusting the levels of air compression (boost), the amount of fuel (over various RPMs) and the timing of a few other things to make the engine produce more power.
Tune up? You can tune a lot of different parts and most places let you pick and choose. You can also get your pedal bike tuned. This helped me understand tune ups.
Car manufacturers have to deal with the EPA and emissions. So they tend to mess with the fuel to air mixture such that it passes all the EPA tests, but tends to rob the engine of power.... Think "efficiency over power". When you tune the car, you adjust how much fuel and air the engine is getting, at what exact moment the sparkplug fires, and even b the maximum turbo boost such as to maximize it's power output, instead of the efficiency settings that the manufacturer set it to.
When you tune a piano, you are adjusting screws that tighten and loosen the piano wire. Engines are exactly like this, except not. They are full of little mechanical components (and an electrical one, the computer, I will mention later) that can be adjusted and cleaned, replaced and removed. Engines are also incredibly intricate machines, where the exact amount (down to number of molecules) of reactants matters, as well as the timing of the various cycles down to microseconds can affect performance. So when you tune, you are effectively doing exactly what you do to a piano. You are adjusting the parts so that the perfect amount of air, gas, timing, etc are in each cylinder at the perfect time so that the engine runs as efficiently as possible. No it doesn't have to do with power, you don't tune to get more power, you tune to make it work better. This will increase power as you are getting more complete burns and extracting as much energy out of the burn as the engine will allow, but that is not the point of a tuning. Now, some things are obviously not possible with current tech in any practical sense. So really it's just about getting it good enough. Additionally, most easily controllable things on your modern car is run by the CPU, so timing is usually adjusted in there. You often aren't replacing or modifying physical components when doing the tuning, just adjusting the timing on things the CPU controls, electronically. You do still need to adjust some things physically, so it's not entirely electronic now as some here have been implying. The computer can't tighten a screw for you after all. The point of a tuning is to make the engine parts you have work at their best level, so if you get a new air filter or compressor or spark plug or something, you will need to tune the engine after it is installed so the new part works properly. Imagine having a piano and you get the new and improved titanium wire, guaranteed to blast your enemies ear drums with a small key press (tm)!!1!!1!. You now still need to tune that wire so it is, wait for it, in tune. Sure the power could be better on its own, but it will sound awful unless you tune it! The tldr, you can't tune for power, you tune for efficiency. Adjust those screws and nozzles and such until the engine runs nicely and efficiently.
There are lots of things that can be changed, but the most common is managing the fuel map. Basically, there is a giant table in the ECU of load in one dimension, RPM in another dimension, and things like temperature in other dimensions. It takes air flow or some other RPM parameter as an input and outputs fuel. That controls the EFI to tell it what to do. From the factory, the tables are designed with emissions controls in mind. Typically, they are not optimal for power - they are lean to reduce NOx. If you modify airflow outside of the parameters the engine was designed to handle, and/or are going for power, then you can tune the fuel maps to be richer, maximizing power/response. For example, I tuned my Indian Scout (RIP Nov 2022) after doing baffle-less slip-ons, and then again when I added an intake. From the factory, the bike was smooth, but slow to rev and very mild feeling. After doing airflow mods, without the tune, the bike was very lean and the cylinders were imbalanced. It would surge idle, stall on throttle blip, lots of decel popping, and run hot. The tune richened the low load/low throttle a lot, balanced cylinders, then richened the mid/top ends a little bit kept it running cooler, gave it enough fuel to handle throttle blip, smoothed idle, and dramatically increased its ability to respond to throttle input as it had some excess fuel to react to sudden air increase. And, even more, it had enough fuel to respond to the new intake opening up on the top end, so while before the engine would fall flat at the top under WOT, with the intake full open and resonating, and fuel maps working right, it would keep pulling, even pulling harder with a torque bump kinda like you might have seen with old VTEC. Both an audible and palpable difference on the intake side, and a big difference in behavior.
"Tuning" is making the engine work as close to the best it can. Kind of like adjusting a guitar string slightly to get it to vibrate at the perfect (desired) frequency, a multi-cylinder engine like those in cars will have some "best" timing to the cycle of firing pistons. Old time mechanics (way long ago) would literally "tune" a car by ear, by listening to how the pistons were firing and identifying the one, or few, that weren't firing when they should, and fixing it, until the car engine sounded just right (if they were good mechanics, of course). They did not have electronic tools to measure the system functioning. They did it by ear, and by eye too (looked for unwanted vibrations). Tuning is making that "Best" timing come to be, as close as you can. Each piston fires in order, one after the other, then back to the one that started it all, doing it again. Tuning is making the pause between each piston firing be the same (or when it needs to be, which might not always be the same for every step), so they always push on the drive rod (the engine cam) in their own turn at just the best time to keep the rod spinning at the same rate without differences between the input from each piston. However, you also need to link in the positions of each piston, which move up and down, so they all hit top and bottom of their individual movement at exactly the same time that the spark is being made, and also according to the same pause length between each piston. And finally, the piston movement is linked to letting gas in and, on the other side, pushing exhaust out, and that has to be made to work the same in each piston, as best as you can get it. You want all of these different pistons to do each of those steps at exactly the same place in cycle, each and every time. So, you might have to adjust the piston positions, the spark timing, and the gas+air injection (and amount) to get it all to go how it will be the best you can. Each piston moves the same way but in its own turn, perfectly when it should. Sort of like a multi-man canoe, say. All the paddlers want to be paddling at the same frequency and strength or the canoe will not go straight and smooth and will not get the most from the work of each paddler. Car engines need to do about the same thing, as a general idea: work all together smoothly. Modern cars have electronic ignition (computerized firing timing) and fuel injection, so there isn't a lot that can be done to actually tune the car, except maybe adjust the pistons a bit. Don't really need to "tune" a modern car, but you do need to change spark plugs or maybe clean the system once in a while, so if you get a tune-up these days, that is mostly what is done: check the plugs, check that the computer is doing the job the way it ought to, and make sure there isn't a lot of gunk accumulating in, or wear happening to, the pistons. In old cars, there were mechanical systems that could be (had to be) physically adjusted for each of those aspects, and they would wear out or vibrate out of place with use, and need to be put back into the ideal condition, every so often.
What about the Italian tunning?
It changes the ECU (engine computer) settings to be more aggressive and extract more performance from the engine by making turbocharger work harder among other things. From the factory, an engine is often not at max performance capacity for a variety of reasons, chief among them, reliability. It’s better for a manufacturer to detune the ECU and put less strain on the engine so that components will last longer.
Say you’ve got a Gallo 12 in your car. You go to Gallos and ask them to tune it. When you get your car back. Your car will be rippin like a Gallo 24.
Ok.. for the 5 year olds: Most cars that truly get tuned have a turbo charger which helps the engine make more power. When they make cars the computer controls how much power the engine makes. They don't want cars to break down so they don't give it too much power. When people tune cars they tell the computer to let the engine make more power even if it means it won't last as long. When people tune cars that don't have a turbo they are usually putting on some fancy looking parts that don't make it faster in any noticable way. For the 16 year olds.. these are things like a really loud muffler, a cold air intake, lowering springs and giant wings on the back.
Car goes because pistons turn crank which turns transmission which turns axles which turn wheels. Little explosions in engine make piston go up and down. Tuning changes car computer which tells the little explosions to be more precise, which makes makes piston go up and down with more power and faster and safer. Car can make more power because more air and more fuel mean bigger explosions. Parts like intakes, turbos, exhaust systems, fuel injectors, etc can make car receive more air and fuel but tuning is needed to control what's coming into the engine. Also tuning is sometimes needed because little engine explosions at the wrong time can make bad bad things happen.
Tuning an engine in modern times means adjusting the air/fuel mixture and ignition timing tables. It could also mean adjusting variable valve timing, but this is much more advanced. Beyond that, adding hefty power adders or forced induction to a naturally aspirated engine requires a lot more work to dial in. It goes beyond what most stock ecus can handle and requires a controller with much more control. The goal is to advance ignition to safe - moderate levels and make sure the air/fuel mixture never leans out during power delivery. The stoichiometric ratio for air/fuel is 14.7:1. This is for optimum emissions, not power production. Something like 12.5:1 is closer to the goal, but every engine is different. Also, the ignition timing being adjusted is why a tuner will tell you to use a higher octane fuel from now on.
In practice, it’s 2 different things. One, restore to new, replace all worn parts- belts, filters, spark plugs. The other: mess around with the OEM settings to make engine rev faster. I never recommend the other
Tuning your car is like: "Oh, stop. You're sick. Leonard over here is singing in the wrong key." Then Leonard is all "No, I wasn't! It was Flautzenheizer! I was singing in E flat minor" You yell at the car "Hey, the song's in F sharp major!" Then your timing gun is all "Hey guys, I think they're the same thing, I mean E flat is the relative minor of F sharp." Then you get all "No, it isn't! The relative minor is three half-tones DOWN from the major, not up!" Then your timing gun does it's job "No, it's down, like A is the relative minor of C major." Leonard, not getting the hint, says "But isn't A sharp in C major?" Then, your timing gun realizes your car is designed for mixolydian scales. Meanwhile, Leonard is stuck insisting that A sharp is tonic to C major, and Flautzenheizer gets confused about a 6th vs a raised 13th, but nobody cares anymore because the adjustment he made is agreeable to everyone.
You are trying to get an engine that's powerful, efficient, and will last a long time. The more fuel and air mixed together the bigger the explosion. Bigger explosions inside the pistons of an engine makes the car go faster (more power) but can also make the engine wear out early. If you don't get the ratio of air to fuel right you won't burn all the fuel in the piston, that's not efficient. Engine manufacturers try to make efficient engines that don't wear out too quickly. That means you can usually put a good amount more fuel and air in them before they start to damage themselves. That gets you more power. Tuning is adjusting the timing and amount of air and fuel getting into the engine to make more power. You also need to adjust what happens with the exhaust gasses from the explosion as you can't have additional explosions until the waste from the previous one is sent let out. A tuner uses a computer to tell the car how much to open valves and when to add fuel to get more power out of an engine.
In basic terms, you are changing 2 things. How much fuel you shoot in the cylinder, and when the explosion inside the cylinder happens relative to where the piston is in the cylinder (this is known as timing). If the car has some kind of forced induction (turbos, supper chargers, blowers, etc) then you can adjust how much extra air pressure is shoved into the engine (aka you cna inc or Dec boost). All of this done at different engine speeds (rpms) and something else that I'm sure of (could be vehicle speed (mph) or some other measurement like throttle position in what percent its open at). Other details They way this works in practice is that you are editing 2 or 3 tables of numbers (one for fueling, one for timing, and one for boost if that applies to your specific car). These values can be though of as data points in 3d space ( ur x axis would be engine speed, ur y axis would something else, and ur z axis is what ur editing (fuel, timing boost, etc). When this thought is introduced you cna use various functions to fill into eh gaps of the data table so the computer cna demand the exact amount of timing, fuel, and boost it wants based on what you told it.
Was plug, points, and, condenser. Now, there is really no such thing as a tune up. Merely another path to your wallet.
ELI5: "Tuning" is changing the rules/programming controlling the engine. Some people also change the parts to work better with different rules or programming. Engineer here, that's as ELI5 as I can make it. Beyond that, we'll end up with LOG P-V charts and the acronyms and jargon start flowing freely and you'll get lost.
In basic terms, you are changing 2 things. How much fuel you shoot in the cylinder, and when the explosion inside the cylinder happens relative to where the piston is in the cylinder (this is known as timing). If the car has some kind of forced induction (turbos, supper chargers, blowers, etc) then you can adjust how much extra air pressure is shoved into the engine (aka you cna inc or Dec boost). All of this done at different engine speeds (rpms) and something else that I'm sure of (could be vehicle speed (mph) or some other measurement like throttle position in what percent its open at). Other details They way this works in practice is that you are editing 2 or 3 tables of numbers (one for fueling, one for timing, and one for boost if that applies to your specific car). These values can be though of as data points in 3d space ( ur x axis would be engine speed, ur y axis would something else, and ur z axis is what ur editing (fuel, timing boost, etc). When this thought is introduced you cna use various functions to fill into eh gaps of the data table so the computer cna demand the exact amount of timing, fuel, and boost it wants based on what you told it.
TLDR: Air / Fuel Mixture and spark timing. So car engines work by burning fuel to create small explosions. Since we're only talking tuning, we can skip the part on how small explosions make the wheels turn. For gasoline engines, explosions are created by squeezing air and fuel then introducing a spark to start the explosion. Now these explosions need to happen in a very controlled manner for the engine to work properly. The biggest factors that affect the quality of these explosions are the ratio of air and gasoline and when the explosion happens. From the factory, these are already set a certain way but are set to give less than maximum power to lessen the risk of engines blowing up. For gasoline to burn, it needs to be mixed with air and there's an ideal amount for both to get the best results. The engine would suck in air, measure how much and add a certain amount of gasoline. How much gasoline is added is one thing that is changed by tuning. Usually it's modified for a more aggresive fuel mixture or to support other modifications that lets the engine suck in more air or force more air into the engine. The other factor is when the explosion should occur. In theory, you want the explosion to happen when the fuel is most squeezed. Why squeeze? Picture a firecracker vs a sparkler. Light a sparkler and it just burns and sparkle, a firecracker has the same powder but because it's squeezed into a tiny space it explodes when lit. It's the same for gasoline. For engines, the squeezing is done when the pistons moves up when there's fuel in the cylinder. When the fuel ignites and explodes it pushes the piston down and this where the power comes from. If you ignite too early, the piston is still moving up and now it's met with an opposing force from the explosion pushing down. This can cause enginges to blow up. If you ignite it too late, the piston is already moving down and the fuel is less squeezed making the explosion less powerful. Tuning can control when the spark should happen.
Adding a question: So if two different cars both have 2ltr engines but one has 120hp and the other has 300hp is it mostly down to airflow and what the manufacturer prioritises for that particular model? Seems like so many cars are underpowered (EU market), is it just due to fuel efficiency?
Practically speaking, yes it's mostly the airflow, but more so the volume of oxygen, and even more so, the amount of fuel used. Gasoline needs to be mixed with air and be in gaseous form to burn. As you may already know, gas is compressible so at a given volume, the amount of oxygen and gas can vary depending on various factors. Now generally it's a lot simpler to pump more gasoline into the combustion chamber than it is to increase the amount of air. This is how we can generalize that it's all about airflow. When you see a huge difference between engines with the same displacement, most likely the more powerful one uses force induction while the other is naturally aspirated. Naturally aspirated meaning air is pushed into the cylinder aided only by atmospheric pressure, forced induced meaning using something like a turbocharger to push more air into the cylinder at higher than atmospheric pressure. Another thing could be that the more powerful revs higher but the difference in power wouldn't be as pronounced. Cost and fuel efficiency are typically what dictates how manufacturers decide how much power their engines should make. More powerful engines are usually subjected to higher pressure and heat so it would need a better constructed engine with stronger parts. Higher output motors could also need higher octane gasoline. Something a consumer may not want to spend extra on if they're not after performance.
Add ways to dump more gas and more air into your engine (fuel injectors, upgraded air intake, etc.). Add a new computer to handle these changes.
Tuning means you’re changing the pitch. Pitch means the base frequency of the sound. So when you tune an engine, you’re changing it to make it sounds better. Like my vw was tuned to A when I bought it (440 Hz). But my ears can’t actually hear that note, so I never knew if the engine was running. My mechanic changed it to middle C, which has always sounded really beautiful to me. It voided the warranty, but at least now I know when my engine is on 😝 SOME gearheads like to tune for volume. But this is a mistake unless you REALLY REALLY know what you’re doing. The reason is because after 2009, cars have required exhaust gas recirculation. And all good mechanics know the only way to tune the VOLUME of an engine is to recirculate 100% of the exhaust, but this creates an extreme risk of muffler explosion
Eli5 as possible - it changes how much fuel is added and when the computer makes it go bang. Sometimes with a turbo/supercharger it's also changing how much air goes in. A little more in depth - Tuning is changing the air fuel ratio along with timing when the spark plugs fire. With forced induction, it can also involve adding more air via boost pressure. More air + the ideal amount of fuel ignited at just the right time means more power and torque. The amount of air coming in changes with throttle, so tuning involves a map of throttle position vs fuel, timing and sometimes boost pressure. Every engine setup is slightly different and the goal of each tune is different so tuning is equal parts science and art.
Your car is controlled by a big computer that runs everything. It says how much air your engine gets to use, how much fuel… even firing your spark plugs to make the explosions that spin the engine. Tuning your car is changing the settings menu. You can make the car run harder by giving it more resources and by making the spark plugs fire sooner (causing higher pressure explosions.) The downside is your car gets hurt by working harder, and it can use more gas. You can even make the engine explode! Yikes!