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Introducing our 1987 Porsche 924S EV Conversion

15350 Views 87 Replies 17 Participants Last post by  lordmundi
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I've been lurking on the threads for quite a while but want to introduce our father-son EV conversion project on our 1987 Porsche 924S (which my son has affectionately named "Perl"). We are super excited to make steady progress toward our 80's inspired EV conversion.
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I am not a Porsche guy, so I have been surprised by just how much I've enjoyed learning about the Porsche 924 and 944 and their history, not to mention the community around them and just how much people love them, warts and all.

We searched for a car for a while - our criteria being something aerodynamic, light weight, manual transmission, interior and exterior in decent shape but a blown or missing engine. Luckily, we found one in Perl!

What we have done so far - removed the engine, removed the exhaust, cleaned up the engine bay, got all of the lights working and mostly converted to LED, started rebuilding the brakes, and removed the transaxle (so that we can remove the fuel tank). It's been so much fun learning about each piece. We also 3d printed a cover for our torque tube and 3d printed a model of a hyper9 motor to assess how it might fit in the front.
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Where we are and questions we have - so we are about to invest in a motor/inverter and batteries. While I was initially thinking a Hyper9, I've recently become much more interested in the Nissan Leaf motor (I think it will fit better in the engine bay and will be much more affordable). If we do go with the hyper9, i think we would need to shorten the drive shaft to let the motor fit behind the front cross-member of the car, which isn't a huge deal but not super fun either. But in terms of the Nissan Leaf motor, I've been researching and trying to understand options like the openinverter project, and the thunderstruct VCU etc. My issue is every time I search for things on the leaf motor I see tons of threads and videos and I'm not sure what the more recent advice is. I know that so much development has been done in the last few years I guess I'm not sure on what the most current experiences are in dealing with a leaf motor, and what batteries and controllers are being used. Maybe my google-fu is just poor to find the most recent stuff.

Along with trying to find that information (mainly to just give me confidence to go make some purchases), I'm also a little curious about people using batteries with the leaf motor. The specs I'm reading say that motor normally runs with high voltages - something like 350 - 400V from the leaf batteries. How are people generating voltages that high? Are you forced to use the leaf batteries so that the voltage is that high? Or is there some way to use tesla battery modules and not require an insane amount of them in series? I guess I'm just looking for any experiences people know about in terms of what battery packs for an leaf motor EV conversion look like.

Other problems I haven't sorted out in my head yet - how can I at least get enough heater capability such that you can defrost the windshield (which is a safety issue)? Also, if I put a large amount of weight in the rear of the car (more than the weight of a full gas tank), can I just buy stiffer or adjustable shocks?

If anyone has any advice or insight we would love to hear it. We are really looking forward to learning and making memories with this project and hopefully sharing it with everyone else.
  • Our automotive skill level: moderate (I know my way around cars a bit, but haven't ever restored a car from top to bottom)
  • Electricity skills: I have a background in electrical engineering, although I know just enough to be dangerous.
  • Range goal: just something reasonable for driving around Houston. I think if we can get 100 mile range that would be great
  • Performance: nothing insane. Just something fun to drive.
  • Money: whatever it reasonably takes to get something working and make memories with my son.
  • Parts we are considering: Nissan Leaf motor. Not sure on batteries.
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First of all, awesome car and awesome project! The 924 with it's rear transaxle configuration is just screaming for a rear-mounted LEAF drivetrain and conversion. Use the 200hp LEAF inverter and really make it scream. Front mounted motor is a waste of space and potential IMO.

Of course you need to visit www.resolve-ev.com and check out the Resolve controller and the creator's own EV 924 if you haven't already seen it.
great info. I haven't seen that video yet. I guess i just haven't considered doing it rear mounted but I certainly can. I guess i just need to figure out how one would go about attaching the motor to the rear wheels and where everything would be welded and whatnot. Since it seems so common to just replace the engine with a motor i just figured that was the easiest way to go.
It's certainly more common but I think not as good. If you mount the Leaf drivetrain in the rear where the transaxle lives, then you just need to adapt the CV axles from one transmission to another. That is actually pretty simple in the big scheme of things.
maybe i just need to "see" it. I've got two wheels coming out each side of the transaxle... and only one output on the motor... right?
This project is very exciting, please keep us updated on it. I would recommend you take videos of your project and post it on YouTube both for memories and for us to enjoy what you are doing. Good Luck!!!
absolutely... we've been taking some short videos as journals and will be putting them on youtube soon. I'll be sure to post notifications in this thread as well!
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Our first video in our father-son EV conversion series is now out:
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watch out for excess battery heat if you go for the 110kw inverter unless you fit the newer and higher amp leaf battery pack in it as well. I just learned that a 110kw inverter and 350v pack takes about 315 peak amps which would melt a 24kwh battery pack (I assume).
thanks. I'm not sure I understand everything you are saying. But right now we are planning to use the Nissan inverter that came with the leaf motor.. i believe both were from the same vehicle which i think was a 2015 Nissan Leaf. Is that still a concern?
part 2 is up:

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Part 3 of our Porsche 924S EV conversion series is up:
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Part 4 of our father-son Porsche 924S EV conversion project:
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I vote to keep your driveshaft and mate your Leaf Motor to your existing gearbox. Keeps the car more original, keeps a gear shifter you might enjoy shifting whether you need to shift it much or not.
well, we thought about this but the main support member for the front end axle runs almost in parallel with the drive shaft, and the motors I investigated would interfere with it. Which would require us to either offset the motor, or somehow shorten the drive shaft to move the motor further back into the middle of the car. Given that the leaf gearbox already has a differential, it seemed like maybe less work and a more direct solution to just hook it up to the rear wheels directly... not to mention all the weight we save from the big transmission and the torque tube and drive shaft. That's just our current thinking though.
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Father-son Porsche 924S EV Conversion Part 5

More problems and frustrations with LED flashers and LED blinker bulbs. Let us know if you have any ideas! Also we got our engine bay cleaned and we started rebuilding our front brakes. Charlie wanted to paint them red, so we got them primed with self-etching primer and then painted with Cherry Red color.

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Father-son Porsche 924S EV Conversion Part 6

In part 6 we eventually figure out a method to remove the transaxle from the Porsche. We eventually realized we needed a special "triple-square" bit to separate the axles and were able to get through that challenge. After the transaxle was removed, we completed the front brake rebuild including new rotors and Charlie's pretty red painted calipers. Lastly we showed off some new Nissan Leaf parts that arrived. Oh, and Charlie's new video intro and outro!! Full project playlist: https://www.youtube.com/playlist?list=PLnMVTS2-3X_C_09iLgKw9IFBuqwSWlXQ3

@lordmundi great project! I wish I had enough time and money to work on a similar project with my 14 y.o. son.
I think it's gonna be valuable for you to check out this project: https://youtube.com/playlist?list=PLRAbBvvHWdlKqTgyUZbSfx-7iv5cn3Jxa They mounted Leaf stack directly to a Porsche's rear wheels.
thanks so much! Yeah, we have watched quite a few of Shane's videos. There is a lot of great inspiration out there.
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Father-son Porsche 924S EV Conversion Part 7 - Nissan Leaf motor spins for the first time!

This was a big milestone for us. We paused on some of the work under the car and started focusing on setting up our bench-top test environment. We had to get a bit creative since we didn't have a battery pack yet, and while we were waiting on parts we tried to 3d print various platforms to mount components to. But the big moment was when everything came together to finally let the Nissan Leaf motor spin for the very first time! Full project playlist: https://www.youtube.com/playlist?list=PLnMVTS2-3X_C_09iLgKw9IFBuqwSWlXQ3

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Father-son Porsche 924S EV Conversion Part 8 - Thunderstruck/Leaf bench test setup and walkthrough

Some of our previous videos featured the benchtop test setup we are using to try and get components working before mounting them in the car. This video walks through that test setup along with our motivations for why/how we did things. Hopefully it is helpful to someone else.

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Father-son Porsche 924S EV Conversion Part 9 - Mounting Nissan Leaf Gearbox and Releasing Parking Brake

In this video we discuss getting the gearbox from the Nissan Leaf mounted to the motor and our journey to figure out how to release the parking brake/pawl in the gearbox. We managed to finally get the parking pawl to release after 3d printing a few different "wrenches" of sorts to turn the shaft. Right now the plan is to not use the parking brake in the transmission at all and instead just use the hand-brake, but we may revisit this later.

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For anyone following this build - we are trying to find the high-voltage connector used with the Chevy Volt battery pack... I posted a thread about it here: Need help finding the high voltage battery connector for...

If you can help us find that connector/cable that would be much appreciated!
A slight side-project we have going - a little ESP32/Arduino display to show CAN bus data using IMgui display framework. Currently uses an ESP32-WROOM-32D and a MCP2515 CAN bus interface module. But, we are having issues with it occasionally resetting or sometimes locking up. I can't tell if it is a problem in one of the libraries I'm using or if it is a power/glitch issue. Anyhow, I'm trying not to focus on it too much since we have bigger fish to fry. But it is still fun to think about and experiment with.

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Um, any chance you'd be willing/able to measure those gearbox-to-engine bolts? Need to order one size longer to mount a brace under the head..
yeah absolutely. do you just want the length? I can take pictures of whatever you like... i've got the part numbers for those two (assuming I found the right ones).
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Yeah length from underside of the head to the end would be awesome, thank you. From measuring the motor I have figured out that they are M10x1.5 but not sure about length. Guessing about 60mm? Just want to see if I can confirm before going out hunting for more.
Looks like from the underside of the head to the end is about 65 mm. About 5 mm of that is the unthreaded tip. See pictures below. Also be aware, I think these bolts are aluminum. I'm not sure if there is any concern for dissimilar metals here, but just thought I would let you know. Pictures:

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Hope that helps!
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