Leaf powered RX8

[sfk]

I think the RX8 will be an excellent platform for the Nissan Leaf donor gear to go into.
The car itself is very well balanced and only let down by the reliability of the engine.
The Leaf motor is probably pretty similar in size to the rotary so shouldn't upset the balance.
The RX8 was disregarded because it didn't live up to the FD RX7's legacy.
For this reason they are very common and very cheap to get hold of currently.
But only for a while until they become "the last rotary" and start to command classic prices.

I'm considering picking one up with a manual transmission and ruined engine to mess around with.
So I'm interested very much in your progress.

[doobedoobedo]

Yes they are really nice cars, 4 usable seats, great handling. Severely let down by the durability of the engine, hence cheap and pretty readily available. Just need to watch out for rust, the one I've got appears to be solid with no sign of rust where they usually go.

[doobedoobedo]

A couple of pics of the car.

[doobedoobedo]

Thought I'd just give a quick update.

I've been slowly but surely stripping out all the oily bits, I was hoping it was going to be a bit quicker than this, but whoever worked on various bits of the car before doesn't seem to have believed in torque wrenches and everything appears to have been done up to the 'as tight as humanly possible' setting. I snapped a T-Bar undoing one of the wheel nuts! On the plus side I've only sheared one (small, unimportant) bolt. Engine and box should be finally coming out this weekend .

[Tremelune]

Some of the best money I've ever spent was on an electric impact driver.

[doobedoobedo]

That was something I have been considering getting and I think it would have helped with the wheel nuts. I even have a set of impact sockets which I got for their depth, so I've really got no excuse...

[sfk]

Sounds like an impact gun wouldn't even shift those fasteners, if you're struggling and breaking hand tools.

Great thing to have though.

[doobedoobedo]

Well I finally have a big hole to fill. Rotary is seriously heavy for it's size.

Still need to remove the fuel tank and diff, but I can move it into my garage now.

[jnsaff]

Have you kept track how much weight you have removed as the oily bits and what’s the general budget for adding EV stuff?

[doobedoobedo]

No not fully, I have a rough idea though and I still have all the bits I took off. I joined the owners club, and have a spreadsheet with the weight of every single part on the car (down to individual bolts!) ie. the engine with no accessories is ~132Kg, the gearbox ~45Kg etc.

[arber333]

No not fully, I have a rough idea though and I still have all the bits I took off. I joined the owners club, and have a spreadsheet with the weight of every single part on the car (down to individual bolts!) ie. the engine with no accessories is ~132Kg, the gearbox ~45Kg etc.

RX8 has EPAS. But, if you are not careful it may not work after you assemble the gearbox back. You have to correctly install rpm counter wheel or suitable alternative to count engine RPM. If you install it backwards it will show rpm but will not drive EPAS.

[doobedoobedo]

Thanks for the heads up, that was something on my radar. The main ECU has a whole heap of connections to various sensors on both the engine and gearbox and I realise that to get best use out of it I'm probably going to need to fake a few things.

I also intend to use a CAN bridge to get useful things out of the main ECU for driving the instrument cluster, whilst substituting in other values for using it the way I want before forwarding the message to the main bus.

[arber333]

Thanks for the heads up, that was something on my radar. The main ECU has a whole heap of connections to various sensors on both the engine and gearbox and I realise that to get best use out of it I'm probably going to need to fake a few things.

I also intend to use a CAN bridge to get useful things out of the main ECU for driving the instrument cluster, whilst substituting in other values for using it the way I want before forwarding the message to the main bus.

Well no big science is required to get EPAS running. You just have to make the toothed wheel and sensor from the transmssion run together. If you will use transmission than this is a no brainer. You just fit it directly to Leaf coupler.
However if you wont use transmission you have to rotate this wheel so that sensor can read and think car is in idle .
It works for two of my friends... one uses small DC motor to keep idle, another just made a step into the coupler so the wheel fits and another bracket to keep the sensor aligned with the teeth.

[doobedoobedo]

So you're saying two sensor inputs need to be coordinated? Sorry I've not even looked at the PAS yet.

[arber333]

So you're saying two sensor inputs need to be coordinated? Sorry I've not even looked at the PAS yet.

As far as i have tried i see ECM needs RPM info for its function. It then sends CAN msg to EPAS computer and this makes EPAS respond correctly.
I think you need equence of:
- engine running 12V from alternator line
- RPM signal
- ECM online
- EPAS comp listening
- EPAS axle 12V connected

After that i think only yellow engine light remains lit because lambda sensors are missing or something similar... You can easily paint it black or tape it or just remove the bulb...

[doobedoobedo]

So you're saying two sensor inputs need to be coordinated? Sorry I've not even looked at the PAS yet.

As far as i have tried i see ECM needs RPM info for its function. It then sends CAN msg to EPAS computer and this makes EPAS respond correctly.
I think you need equence of:
- engine running 12V from alternator line
- RPM signal
- ECM online
- EPAS comp listening
- EPAS axle 12V connected

After that i think only yellow engine light remains lit because lambda sensors are missing or something similar... You can easily paint it black or tape it or just remove the bulb...

OK I get it now. I knew I was going to need to send in RPM signal. The RX8 has had it's instrument cluster CAN messages reverse engineered so the instrument cluster could be used for racing simulator games, so I'm not overly concerned about the display.

I intend to intercept messages from the ECM, modify any I'm interested in for driving the instrument cluster, and forward the rest. CAN messages to/from the brain and BMS will also go into the module that does this. I want to use the same module to generate any signals I need to trick the ECM in to thinking there's still an engine there, and gather any other signals I need such as direction etc.

[doobedoobedo]

It's been a while since I did an update. I had some space problems in my garage, but they have just been cured with a set of wheel dollies, so more work on the car coming soon.

Off the car I got an instrument cluster and now have the ability to drive all aspects of it. I'll be making a custom VCU to drive the instrument cluster and intercepting some of the signals from the main VCU (vehicle speed for example) to pass on with some modified data for other things in the same CAN message.

I also wanted to retain the original gear knob for selection of forward and reverse and I've modified a sim racing gear selector available on thingiverse to both be more positive and take the RX8s gear knob which is quite heavy. I'll print the final version in PETG. Once I'm completely happy with it I'll put the files up on thingiverse.

Prototype printed in PLA:

[doobedoobedo]

Fuel tank is finally out and it's not looking good for my plan to mount the leaf motor in it's place. I don't think I'm going to have the space . I'm also going to see if the motor will fit where the gearbox was although on first inspection that's not looking too good either. I'll take some more measurements tomorrow and refine my (cardboard) model of the motor.

[arber333]

Fuel tank is finally out and it's not looking good for my plan to mount the leaf motor in it's place. I don't think I'm going to have the space . I'm also going to see if the motor will fit where the gearbox was although on first inspection that's not looking too good either. I'll take some more measurements tomorrow and refine my (cardboard) model of the motor.

My friend was playing with the same idea to just put the Leaf motor where transmission was. In the end he decided to retain transmission. Wise choice since he lives in hilly area and in 4th gear motor strains to power the car uphill. Maybe if you would get a rear diff with higher ratio so final gear would be like 3rd. 3rd is universal on RX8 .

[doobedoobedo]

I was going to get a 5.8:1 ring and pinion set and get that fitted in the diff.

With my 5 speed box 3rd is about 6:1 total, 4th would be 4.4 or 4.3:1 depending on which market the final drive was for (UK is 4.4:1).

[doobedoobedo]

Not done an update here for a while. I've decided to mount the motor where the transmission used to be. I have metal for the frame arriving tomorrow.

Still trying to trick the PCM into thinking the engine is still there. The crank position sensor is a horrible shape and analog, but I'll get there.

On a more positive note I can drive the fuel gauge from PWM now (thanks to someone on another forum giving me the idea). Boards arrived today from JLCPCB and I built one to test, looks like the original sensor resistors were logarithmic so I need to do some maths, but after increasing the arduino's PWM frequency I can set the fuel level with a pot .
The board is very simple, transistor, 2 mosfets and some resistors. If I'd thought to add the capability to use a low pass filter I probably wouldn't have needed to change the PWM frequency, but no real loss. Once I'm satisfied it's working properly I'll put the hardware design and a simple arduino driver for it up on github.

I've also printed a forward/neutral/reverse gear selector based on a sim racing design from thingiverse so I can keep the original gear knob for that original look. I had to change the design a little as the knob is so heavy and I don't want it slipping out under acceleration. It's pretty firm to select now, so hopefully it'll be OK, if not I know how to modify it further.

[rooster]

Love what you have done so far as my RX8 is still sitting in the garrgae and I haven't pulled out anything, yes it still runs whilst I plan the motor geabox combo

I think the leaf uses a 10:1 gear between the motor and the wheels so I am worried that connecting it to the prop shaft will only provide the diff at 3.7:1 - so you won't have enough torque to get underway.
WDYT ?

[kiwifiat]

Love what you have done so far as my RX8 is still sitting in the garrgae and I haven't pulled out anything, yes it still runs whilst I plan the motor geabox combo

I think the leaf uses a 10:1 gear between the motor and the wheels so I am worried that connecting it to the prop shaft will only provide the diff at 3.7:1 - so you won't have enough torque to get underway.
WDYT ?

The 2011/12 Leaf has a 7.94:1 reduction/Torque multiplier between motor and axle. That gives the Leaf quite acceptable acceleration. If you connect a leaf motor direct to the rear diff on an RX8 you will get unacceptable performance.

[arber333]

Yes, i can concur. My Pug with Leaf motor and GBX jumps at throttle input, while my friend has Mazda RX8 with original transmission and Leaf EM61 motor and he needs to start from 2nd or 3rd. Even 3rd is not so jumpy...

[rooster]

So Im thinking about an i3 motor which has 10:1 gear ratio, that would aid acceleration