Dual Fuel, electric rear wheel drive, gasoline front wheel drive

[Frank Lee]

no diff

[Daveedo]

Originally Posted by Frank Lee

no diff

yah, without a differential you'll drag the inside tire around corners because both tires will be traveling at different speeds as your turn. I suppose you could just power one wheel or use two motors on different wheels. I like the idea though.

PS Do it and show us how you do it

[Christ]

LOL I forgot about the no diff thing... would be great in a straight line though!

Ok, so diff stays, motor gets mounted to diff... IRS is still a better option though, b/c with the motor mounted hard to the diff, it's putting more weight on the suspension. with IRS, you're putting no more weight on the suspension than was already there, and you're not incurring any more frictional losses than you would be with a solid rear axle.

In fact, I tend to think you're actually incurring slightly less losses with IRS, b/c you're only subjecting the diff itself to fluid drag, and the axles never see the associated "swimming".

Of course, given that CV axles are most efficient when working in a straight line (in a line that would be suited to a solid axle), you're probably losing that same efficiency gain b/c they're almost never straight.

It still would reduce suspension strain though, (unsprung weight) which is everyone's complaint when coupling motors directly to wheels, even though you can get rid of a large amount of weight at each wheel when using electric motors. (You don't need brakes anymore, technically.) (Legally, you still need them.)

[bendr06]

Im new to this whole idea so bear with me while i try to explain it. What about trying something like this in a pontiac fiero. Mid-engine RWD, so you can use the front, one motor on each wheel. You would get the better regen braking, increase performance and get better mileage from the ICE. my biggest question on that is how do you get the front wheels to travel at the same speed as the rear?

[The Atomic Ass]

Originally Posted by bendr06

Im new to this whole idea so bear with me while i try to explain it. What about trying something like this in a pontiac fiero. Mid-engine RWD, so you can use the front, one motor on each wheel. You would get the better regen braking, increase performance and get better mileage from the ICE. my biggest question on that is how do you get the front wheels to travel at the same speed as the rear?

You don't, really. Realistically, you can get away with separate throttles for both electric and ICE, and under light throttle it'll self-balance. Ideally, you would use a controller that provided traction and torque management to both engines at the same time.

[basjoos]

The Poulson hybrid system mounts two 7 hp electric motors on the outside of the rear wheel hubs of a FWD car. They are designing it so it can be installed on any FWD car.

[MechEngVT]

Originally Posted by Christ

Of course, given that CV axles are most efficient when working in a straight line (in a line that would be suited to a solid axle), you're probably losing that same efficiency gain b/c they're almost never straight.

If you're adding electric RWD to an otherwise FWD car you can save some coin or get more robust shafts with universal joints as rear wheels do not steer. Also universals shouldn't be run straight anyway (it keeps the needle bearings from spinning properly), so you'll be good.

IRS would be better, but not all vehicles start out with IRS and this conversion would be problematic for suspension mounts. You could turn a beam rear axle to a live axle, body-mount the motor and shaft-drive the diff to minimize unsprung weight, although a live axle adds a lot over a beam axle in a FWD car.

[getnpsi]

I posted a similar thread about 6 months ago, called poor mans hybrid. obstacles would be for the end user, having to modulate two throttles. The guy putting it in himself wouldn't care. Not everyones a "mad scientist" so being user friendly would drive the cost and the research up, only afforded by the big car companies. I would totally go for one with a small ac motor in the back operated with a twist throttle, and relocate the e-brake handle or something.

[Allch Chcar]

I've had the same thought, since there hasn't been a light weight RWD compact since the 240sx. Everything's FWD and the Rear is where I'd want the acceleration to go. Making a hybrid just seems the practical solution except everything would have to be DIY fabrication.

Please link your topic getnpsi. I'd like to see it.

[roflwaffle]

I don't think the two throttles would be a huge problem since mixing and matching would only be done during WOT, at least IMO. If we're going slow, just shut off the engine because low load efficiency blows anyway, and if we're above a certain speed where it makes sense to run the engine because it's operating efficiently enough, just make sure the electric motor in the rear doesn't engage unless we turn it on or we have something where it'll kick in at WOT or similar. Doing something similar with RWD is a bit easier as long as there is enough room to mount the motor behind the trans and shorten the driveshaft to accommodate the motor. From what I've read there's a ~1-2% drop in mileage at lower speeds due to spinning the motor around, but it's easier to use, and we can even run accessories on electric power by engaging the gear box assuming we can kill engine ignition, although it's pretty lossy spinning an entire engine over just to run an A/C compressor.