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Introducing our 1987 Porsche 924S EV Conversion

15537 Views 88 Replies 17 Participants Last post by  lordmundi
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 and check out the Resolve controller and the creator's own EV 924 if you haven't already seen it.

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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?
Sort of. The LEAF has a FWD gearbox with a differential and CV axles just like a normal car. The electric motor is bolted to that, the inverter is bolted on top, and then the PDM is bolted on top of that. If you ditch the PDM then it is much shorter. It makes for a very compact drive unit, I'm guessing similar or maybe slightly larger than the Porsche transaxle.

So you replace the transxle with two axles with the LEAF motor+gearbox with two axles.

Check out @windraver's thread for a bunch of photos. He is building a FWD Honda but the same principals apply to using it as a RWD: 1986 CRX EV conversion (Nissan Leaf Donor) - In Progress
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Yeah without the CVs installed it will rattle. I wouldn't run it any more than necessary without axles installed, the diff may start coming apart.
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