[WIP] Smart Roadster Hybrid

[Anders]

I've finished my first relatively simple EV project (The motorcycle behind the roadster in the picture) so I figured it's time to start something very complicated.
Link to the bike project thread

Why Hybrid?
The car has to keep up with ICE cars both during track days and during multiday roadtrips, and it's way too small to be able to fit enough batteries in it to do days of 6h+ spirited driving.
Series hybrid could be an option but this would require a battery large enough to supply the wanted 180kW of power for prolonged periods of time.


Goals
The maximum power output a homebuilt/modified car is allowed to have in Sweden where I'm located is currently 20kW per 100kg. So naturally that's the goal, which ends up being somewhere around 180kW of power. I'm allowed to run a electric traction motor in parallel with the ICE engine as long as I tune the configuration so that they don't produce more than the power-limit together.
So the idea is to run a Hayabusa or equivalent high power motorcycle engine in parallel with a smallish EV motor (Outlander front motor/generator maybe?). With the EV motor filling in the torque gaps of the motorcycle engine in lower rpm. As well as powering the vehicle in reverse.
But since no motorcycle engine makes 180kW out of the box I'd need to boost the ICE engines top end power as well, the smart way to do this is with a supercharger connected to the ICE engine, the fun way of doing this is to run the supercharger with a KIA HSG or similar small high voltage motor.

So ideally I'd use a small hybrid inverter that can already run two motors. I would like the traction motor to be capable enough to drive the car with the ICE engine turned off in slowspeed traffic etc as well as doing the previously mentioned torque-fill role. The logical choice would be the KIA Hybrid inverter that goes with the HSG, but don't think that's been cracked yet.

Parts
Inverter: Prius gen 3 with Damiens dualmotor board?
Tractionmotor: Outlander generator?
Supercharger motor: Kia HSG (Have one already)
Batteries: Kia E-niro PHEV modules ?

I recently bought a home with a garage and I have a spare rear subframe to build on, so the project has no set time limits. Took me about 5 years to get the motorcycle road legal, and I have no delusions of this going any faster.
I have access to a pretty well stocked makerspace workshop so shouldn't be too difficult to do most of the mechanical stuff.

Open to suggestions on what EV parts to use. Seems like people haven't been getting great performance out of the Prius inverter + outlander motor combo so maybe something else is better? This far the only EV part I've bought is the KIA HSG, so everything else could still be changed.

[0tik]

>But since no motorcycle engine makes 180kW out of the box I'd need to boost the ICE engines top end power as well, the smart way to do this is with a supercharger connected to the ICE engine, the fun way of doing this is to run the supercharger with a KIA HSG or similar small high voltage motor.

You just described hybrid system of F1 bolids.
By the way. New speed and braking world record was achieved by a car with 0 (none) hybrid systems. By this I mean to say that if you want racing car - typical hybrid is not the way to go.

Insight's inverter has been cracked already with lebowski brain. Don't ask me for details, I don't know how to make one.

I think the easiest way would be to buy Opel ampera. Strip the engine of auxiliaries until it stops working. Put all the necessary guts inside your smart. Done. You could save weight by using high power batteries from new cars rather than OEM one. Half easy to do if cells have the same capacity- just rewire. Quite difficult when you have to spoof OEM battery. Is the voltage the same?
I'm not sure if power from mg1 can be directly sent to mg2 by open inverter hardware, if you're going to use coupled motors like in volt/Toyota/outlander.

BUT HEAR ME OUT

MIATA! But with 50kw ICE engine coupled to 450h tranny. Battery of your choosing. Now make some code that equalizes ice power output+mg1 regen according to power demand (throttle pedal) and battery max power draw. During cruising ice works as a range extender turning on and off around 50% soh or whatever you choose (as it usually draws 15-30kw from battery). 80kw from BMW pack + 50kw from ice is more than enough for overtaking. If you feel more fancy, you can make your own LTO battery for more power. Good luck finding an ice that would work efficiently (like Atkinson cycle or a diesel) without much auxiliary electronics. Open source ECUs like speeduino also exist. And by the way there's plug n play kit for Miata.

There's one but (apart from money)- calculate weight added by this insanity.

Also there was a thread - someone converted pick up truck into hybrid, but I can't find it.

I just took a step back and re-read your post. Simple answer would be - just buy new hybrid Yaris GR.
Now the real men's answer is- this could work! Weld one hsg to the turbo and the other one to the tranny. Link turbo HSG to throttle. For EV mode make a switch that idles ICE and turbo hsg. Pick neutral gear and it's EV mode. Of course making logic for when to use hsg for propulsion and when for regen is not easy but once you weld and bolt everything together it's just a matter of tuning. I wonder how big battery would need to be though. If you actually can fit phev battery in there, then you can swap HSG for something more powerful.

[jrbe]

There are 48v e-assist turbos and 48v superchargers that oems use and make real power (I don't mean the eBay toys.) The turbo can be used for energy recouperation at certain times.

[Anders]

BUT HEAR ME OUT MIATA!

I don't fit in the early ones and an ND is way too expensive, but a ICE+450H transmission project would be a cool future project, used to have an old Lexus IS-200 that would be a great option for that.

There are 48v e-assist turbos and 48v superchargers that oems use and make real power (I don't mean the eBay toys.) The turbo can be used for energy recouperation at certain times.

Only car that uses an actual electrified turbo that I know of is the 2025 Porsche 911 GTS, the Audi SQ7 and a few other models have a 48v supercharger but those have only been hacked by people who aren't sharing their code. And spin too fast to run with something like a VESC inverter. Otherwise those would be a good option.

Built myself a working table and picked up some stuff for this project, got myself a Holset HX-35 Turbo, a laser scanner and a gen 3 prius gearbox. Will look into taking the MG1 out of the case and setting it up to run off a bike engine on the ICE input while keeping the MG2. Not entirely sure that's doable since the Prius engine spins at about half the rpm of a bike engine so might be more trouble than it's worth to try to redo the internal gearing etc. But there are limited slip diffs that fit the prius so if it does work it could work quite well. And it would be nice to skip the chaindrive.
I can try to do some half decent scans of the transmission case and throw up here in case people wants.

The electric supercharger/Turbo part isn't a critical part of the project, it'll work quite well with just a spicy bikemotor and a Prius MG2, but to me it's an interesting project. A bit of fun unnecessary complexity.


Prius gearbox cracked open


Playing with the scanner.

[Age]

Maybe you already know this project which is "the other way round"
I like the idea of how he distributes the power between the motorcycle engine and the leaf drivetrain:

https://youtu.be/PVlMxQaAf-k?si=w2L9lKm9JMJIK8Ec

[Anders]

Yeah I've seen that Leaf, really cool build.

Should be fine to run the MG2 with a bike engine just by removing the MG2 planetary carrier and welding those two gears together, and then welding the MG1 planetary solid. Will be a lot of heavy pointless steel spinning, but it should work. Have to double check the gearing to the diff but I think it's a pretty reasonable finaldrive ratio.

[jrbe]

Do you have to pass emissions with the car? If so, is it an OBDII requirement?
Bike engine tailpipe emission testing would likely be tricky if required.

[Anders]

I've already been in touch with SFRO (The Swedish association of vehicle builders, the governing body for homebuilt vehicles) and they don't seem concerned about emissions. Reading the rulebook it seems like I might have to run ethanol, but not sure.

[Anders]

Picked up a Gen 1 Hayabusa, so that part is defined. Don't think I can fit the Hayabusa motor and the full Prius P410 gearbox in any reasonable way without designing a completely new suspension system.
So now I'm back to trying to find a good traction motor and compatible inverter, I'm quite fond of the Prius P410 MG1 motor for use in the turbo MGU-H project so ideally I'd find a good smallish traction motor I could run with the Gen 3 Prius inverter. I have a KIA HSG I could use but that seems a bit too small to add any meaningful torque.

Taking MG2 out of the case could work but that seems like a lot of work. Outlander motors are quite compact and nice sealed units so that would be an option but not sure how compatible they are with the Prius inverter.

[johu]

but not sure how compatible they are with the Prius inverter.

Jamies beetle and Toms BMW run this combination and it seems to work rather well

[Anders]

Somethings like that could work, decent amount of space for the inverter and turbo left. That's with the outlander rear motor, HSG is way smaller so could fit in the same config without issue. Would need to do a better scan of both the engine (this is crappy scan I found online) and the car to make sure. Batteries will have to go in the frunk or ideally under the seats.

[muehlpower]

This is an interesting project. I think it's good to electrically compensate for the motorcycle engine's lack of reverse gear. How are you going to solve the differential problem?

[Anders]

That design is using Quaifes limited slip differential designed for motorcycle engine racecars.
https://www.demon-tweeks.com/se/quaife- ... q-eqdf7zr/

Hopefully I can integrate the tractionmotor well enough that it'll compensate both for the lack of reverse and the low torque of motorcycle motors at low rpm to make the car more drivable in traffic.