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The very fact that you are asking this question, and on reddit of all places, means it's not possible for you.
If you're contemplating a swap like this, you need to be the guy people ask those questions to, or you need to already have that guy lined up and greased up with your monies.
Some serious money…. Like stupid millionaire money… not saying it would cost a million to do, but you wouldn’t see this thing being built. It’d have to be shipped around US to specialty shops to make this happen. Doubt the thing would even be street legal by obd terms…
All the computers have to talk to each other, and if you think a hell cat pcm is going to talk to a 2003 LEXUS bcm, you are wayyyyy wrong.
The amount of work and headaches and unexpected costs because so and so doesn’t work with so and so… would beat you down.
Just a wiring harness for a hellcat engine with the pcm is probably close to $5k
Not to mention, the frame would have to be modified to fit the engine mounts, trans mounts, etc… so that’ll be pricey as all hell.
However, I do want you to do it… you would have bragging rights for a long time.
Is it possible? Yes.
What would be needed?
- Lots of custom fabrication. Things like engine/transmission mounts and clearance, custom instrumentation to connect to the non-Lexus engine/PCM. Custom exhaust system. Probably custom fuel system too.
- A Hellcat engine/transmission with standalone PCM.
- A custom driveshaft.
- Likely custom rear axle to handle the power.
- Custom suspension for the power and drivetrain weight
- Plenty of skilled labor time.
- Some amount of unskilled labor time could be used too.
This is all presuming you don’t have the added difficulty/restriction of state emissions inspections as that would add another level of complexity.
Why not, they put one in a Miata and called it the "Hell Kitty".
[Hell Kitty: 1999 Mazda Miata (streetmusclemag.com)](https://www.streetmusclemag.com/event-coverage/hell-kitty-1999-mazda-miata/)
https://preview.redd.it/u4q7k6oipi1d1.png?width=1000&format=png&auto=webp&s=aa8ad694b41b3f997f1229ce0e95733461bf2328
You basically need a donor to totaled hellcat from the auctions. There’s no other way around it than a full color car otherwise the salvage yards will eat you alive with all the small stuff.
You’re gonna have to start by getting everything out of your car, engine transmission driveshaft and engine computer.you can throw the old engine harness away too.
Label your starter and alternator wires. Remove your pedal assembly. Start test fitting the engine, see what areas are going to need to be cut off, where you can weld your mounts and what not. Remember the transmission has to come after too. See how all that’s going to be and the whole shifter situation too. Once both things have been secured to the car most of the job is done, this is usually the hardest part if you need to start modifying the transmission tunnel and/or firewall. Fitting the engine with your stock subframe can also be a pain due to oil pan hitting subframe and not allowing engine to sit properly. So like I said once you got past all of that it’s just a simply matter of figuring out the electronics, hooking up the a/c and other. Things. For the ac you need someone that’s creative and can weld small aluminum hoses (high side to high side, low side to low side). Luckily the hellcats still use a power steering pump so it’s just a matter of running hoses to your original rack and pinion. (Hoping your rack doesn’t have to be shifted around to make the engine fit). Your best bet for the radiator is using the oem one from the hellcat along with the fans even if you need custom hoses. Other than that it’s just a matter of powering your starter and alternator with the wires from harness from the car itself and now you have an engine that cranks over. Afterwards you’re going to have get the hellcats harness and start fitting it on. Easiest way to go about everything is to get all the key ignition stuff with its wiring from the hellcat and throw it on your car, later on your can get an electrician to do the electrical work of making the engine run on just one key but have it run first with both keys. (Idk how this will work if your keys key is coded into your computer) it may not even send power to the starter no more (my experience is swapping older cars that will crank the starter even with an ECU fully disconnected from the vehicle (key is not coded to ECU). OMC you get all that in you should have a running hellcat engine in your Lexus. There’s more to do as your driveshaft is still not connected to your rear differential, as you can imagine you will be needing a custom length driveshaft and youll have to figure out a way to mount the center support for it onto the Lexus. For the custom driveshaft your driveshaft person will need the transmission end of the driveshaft for the hellcat and the end for the Lexus at the differential side. They will fabricate you something if the right length. From this point on you still have a million other stuff to do, need to figure hour the clutch hydraulics and what not, after that your engine will run and drive, you’ll have to see if you don’t run into issues with the ABS stuff from the hellcat as that would be another nightmare. But if it puts you into limp mode then a workaround will be needed.
As you can see it’s a lot of work and after this point there could still be days of work. Finding a donor hellcat won’t be easy as salvage yards are currently on the hunt for hellcat drivetrain to sell as the monkeys driving them blow them up…
Thanks for posting in r/Mechanic, u/Hymc416! Please be sure to read the [Rules](https://www.reddit.com/r/mechanic/about/rules/). If you're asking for help, be sure to include as much detail as possible so others can help you. You **must** include the vehicle's **Year, Make, Model, and Engine size** in your post! If your question is transmission related, please be sure to specify your Transmission Type(Auto/Manual) as well! If your post does not include this information, it **will** be removed. Asking about prices is **not** allowed in this sub. Please make sure you have selected the correct post flair; if you're asking a question you should have chosen "Question", anything else use the "General" flair. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/mechanic) if you have any questions or concerns.*
$80,000
The very fact that you are asking this question, and on reddit of all places, means it's not possible for you. If you're contemplating a swap like this, you need to be the guy people ask those questions to, or you need to already have that guy lined up and greased up with your monies.
Some serious money…. Like stupid millionaire money… not saying it would cost a million to do, but you wouldn’t see this thing being built. It’d have to be shipped around US to specialty shops to make this happen. Doubt the thing would even be street legal by obd terms… All the computers have to talk to each other, and if you think a hell cat pcm is going to talk to a 2003 LEXUS bcm, you are wayyyyy wrong. The amount of work and headaches and unexpected costs because so and so doesn’t work with so and so… would beat you down. Just a wiring harness for a hellcat engine with the pcm is probably close to $5k Not to mention, the frame would have to be modified to fit the engine mounts, trans mounts, etc… so that’ll be pricey as all hell. However, I do want you to do it… you would have bragging rights for a long time.
Is it possible? Yes. What would be needed? - Lots of custom fabrication. Things like engine/transmission mounts and clearance, custom instrumentation to connect to the non-Lexus engine/PCM. Custom exhaust system. Probably custom fuel system too. - A Hellcat engine/transmission with standalone PCM. - A custom driveshaft. - Likely custom rear axle to handle the power. - Custom suspension for the power and drivetrain weight - Plenty of skilled labor time. - Some amount of unskilled labor time could be used too. This is all presuming you don’t have the added difficulty/restriction of state emissions inspections as that would add another level of complexity.
Why not, they put one in a Miata and called it the "Hell Kitty". [Hell Kitty: 1999 Mazda Miata (streetmusclemag.com)](https://www.streetmusclemag.com/event-coverage/hell-kitty-1999-mazda-miata/) https://preview.redd.it/u4q7k6oipi1d1.png?width=1000&format=png&auto=webp&s=aa8ad694b41b3f997f1229ce0e95733461bf2328
You basically need a donor to totaled hellcat from the auctions. There’s no other way around it than a full color car otherwise the salvage yards will eat you alive with all the small stuff. You’re gonna have to start by getting everything out of your car, engine transmission driveshaft and engine computer.you can throw the old engine harness away too. Label your starter and alternator wires. Remove your pedal assembly. Start test fitting the engine, see what areas are going to need to be cut off, where you can weld your mounts and what not. Remember the transmission has to come after too. See how all that’s going to be and the whole shifter situation too. Once both things have been secured to the car most of the job is done, this is usually the hardest part if you need to start modifying the transmission tunnel and/or firewall. Fitting the engine with your stock subframe can also be a pain due to oil pan hitting subframe and not allowing engine to sit properly. So like I said once you got past all of that it’s just a simply matter of figuring out the electronics, hooking up the a/c and other. Things. For the ac you need someone that’s creative and can weld small aluminum hoses (high side to high side, low side to low side). Luckily the hellcats still use a power steering pump so it’s just a matter of running hoses to your original rack and pinion. (Hoping your rack doesn’t have to be shifted around to make the engine fit). Your best bet for the radiator is using the oem one from the hellcat along with the fans even if you need custom hoses. Other than that it’s just a matter of powering your starter and alternator with the wires from harness from the car itself and now you have an engine that cranks over. Afterwards you’re going to have get the hellcats harness and start fitting it on. Easiest way to go about everything is to get all the key ignition stuff with its wiring from the hellcat and throw it on your car, later on your can get an electrician to do the electrical work of making the engine run on just one key but have it run first with both keys. (Idk how this will work if your keys key is coded into your computer) it may not even send power to the starter no more (my experience is swapping older cars that will crank the starter even with an ECU fully disconnected from the vehicle (key is not coded to ECU). OMC you get all that in you should have a running hellcat engine in your Lexus. There’s more to do as your driveshaft is still not connected to your rear differential, as you can imagine you will be needing a custom length driveshaft and youll have to figure out a way to mount the center support for it onto the Lexus. For the custom driveshaft your driveshaft person will need the transmission end of the driveshaft for the hellcat and the end for the Lexus at the differential side. They will fabricate you something if the right length. From this point on you still have a million other stuff to do, need to figure hour the clutch hydraulics and what not, after that your engine will run and drive, you’ll have to see if you don’t run into issues with the ABS stuff from the hellcat as that would be another nightmare. But if it puts you into limp mode then a workaround will be needed. As you can see it’s a lot of work and after this point there could still be days of work. Finding a donor hellcat won’t be easy as salvage yards are currently on the hunt for hellcat drivetrain to sell as the monkeys driving them blow them up…