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

[getnpsi]

Load a 240sx with a buncha batteries and/or new drivetrain in the front and here comes understeer.

The poor mans hybrid wasnt my thread, it was a guy thinking of using an awd minivan, plenty of space to work out theory there.
http://ecomodder.com/forum/showthrea...ight-2233.html

[Allch Chcar]

I was thinking more along the lines of a Geo Metro with it's motor turned into a generator including removing the FWD. I figured it was easier to do that then deal with combining or manually adjusting the two throttles. You'd have to have a training session before anyone could borrow your car. The problem is still the prius inverter, 500volts straight to the motor during heavy acceleration or during highway cruising is a little harder to wire up. During that time it's easier to think the motor should be direct driving. But I'm fairly confident that running the fuel which I'm looking at ethanol through the engine which runs between 1500rpms and 3000rpms min/max, converting that with an alternator sized for maintaining a top speed of 70mph through the inverter to the motor hooked directly is just as efficient or within 10% of the 85% efficiency of the engine hooked up to a manual transmission and FWD drivetrain.

And getnpsi, that's why they put batteries closer to the rear wheels. It's easier to put more rear bias with the heavier lead acids. Just don't oversize the battery pack or overload the rear end.

For using an AWD van, it wouldn't be anymore fuel efficient unless it eliminated idling, maintained speeds below 35mph and limiting the engine to it's optimum fuel efficient range, which is 35mph in 5th gear for the Metro but can be upwards of 50-60mph in a lower geared sports cars such as the Corvette. And then you'd have to swap the engine for a smaller one to really reap the benefits, you won't need the big v6 anymore if you use the electric motor to accelerate to 35 and you'll eliminate the need for anything shorter than 3rd and 4th gear.

[evolutionmovement]

A Subaru would be very simple. Swap the AWD transmission with a FWD one (pre-1994, cheap, and would fit nearly any Subaru after 1990 that you'd want to use) and attach the motor to the rear diff. The cars are made so monkeys can work on them and the suspensions are built like tanks, too. Of course, that also comes with a bit of a weight penalty, but a first generation Impreza or, even a Legacy, is reasonable. Any suspension upgrade necessary to compensate for the extra weight of batteries is also easily done and available.

[Allch Chcar]

Yeah, Subaru. I'm only in preplanning, but I'm researching whether it'd be easier to get a RWD like a Mustang and put the ICE and a dual shaft AC motor inline and use a 2 speed powerglide converted to manual. I'm thinking that using the pedal with a potentiometer and converting the engine to drive-by-wire aka electric throttle control and using the same signal for the AC motor would be do-able but I haven't found out how yet. I'd like to use a 1.3l/1.4l converted to E85 which would be enough for 70mph max and I'd like to try something like converting to Atkinson cycle or 6 stroke but those are only dreams.

The easy part is putting an off switch for the ICE. But I'd have to put a clutch between the ICE and the AC motor and either manually switch on the ICE or get the ICE to switch on when the battery level drop. I'm thinking I'll just get a 5kw/hr pack of Thundersky's LiFePo and use something like the Prius'(the best example I've got) 40%-80% charge cycle. Without the v6/v8 and with a smaller battery pack and Aero mods it just might get the 40 mp(GGE) I'm setting as the projected goal.

[Drive Stick]

You know, I get upset every time I see threads like this because I have an uncle who has the monster garage, every tool under the sun, the know how (he works for the power company) access to all the junkyard parts and controllers I would need to actually build such a car (and i have a spare subaru AWD wagon I could use or a neon coupe) .. and for some reason or another my uncle doesn't have any interest in knowing me for the most part.

I too, have wanted to retrofit a car with dual drive systems such as electric motor to power the rear wheels, and I'm so close I have everything I need except for the one person on eart who CAN help me make it all happen.

Well, we can all keep dreaming - but if he ever does gain interest in me and my ideas it'll be done.

[aussie_modder]

For the home-built special, why not consider the use of hand throttles similar to that used in a twin engined aircraft? if established with a electronic throttle control, you would effectively have easy control of both engines at the touch of your fingers.



I've considered something similar for varying the degree of engine braking in an ICE. By varying the degree of EGR, fan braking, air-con temperature, you can potential vary the degree of engine braking experienced. [CAT haul trucks have their braking system lever next to the steering wheel. the emergency brakes on the older models are sprung loaded- perfect for braking on the straight.... and some corners]

If you were to maintain the pedal accelerator for the ICE, and still incorporate a hand throttle for the electric motor with forward and rear movement (neutral point- electric motor off, rearward-> increasing regen braking). A fail safe, similar to that used withcruise control would be needed to automatically stop forward electric motor propulsion when you touch the brakes or clutch for example.


The tech people would need to clarify for me how you would wire it up so vary the regen braking available.

[evolutionmovement]

I like the aircraft throttle idea. But I'm biased since I have a similar idea to use a hand throttle to manually control a CVT for a project I can't afford to build and probably never would as it wouldn't be practical, just a blast to drive and unlike anything else on the road.

[Allch Chcar]

Originally Posted by Drive Stick

You know, I get upset every time I see threads like this because I have an uncle who has the monster garage, every tool under the sun, the know how (he works for the power company) access to all the junkyard parts and controllers I would need to actually build such a car (and i have a spare subaru AWD wagon I could use or a neon coupe) .. and for some reason or another my uncle doesn't have any interest in knowing me for the most part.

I too, have wanted to retrofit a car with dual drive systems such as electric motor to power the rear wheels, and I'm so close I have everything I need except for the one person on eart who CAN help me make it all happen.

Well, we can all keep dreaming - but if he ever does gain interest in me and my ideas it'll be done.

Sounds like you got a cool uncle. You should really become his friend. Worst case you can help him with something and maybe he'll teach you something.


The problem with the aircraft throttle is the lack of a "centering" spring. In my mind that's just a necessary safety. With aircraft there isn't a reason to have the throttle revert to 0%. That is probably why a gamepad's control stick was being used in the other electric hybrid. But I see how hooking it up like cruise control might work. If the hand throttle is hooked up to the cruise control assembly, maybe the brake or clutch would cancel the input. Err, or not, I don't know.

Anyway, the hand throttle needs a potentiometer installed at the end of the stick. You wire uses a low power wiring rated in Ohms. If you use a 0-5k pot, you need wiring that does a little over 5k Ohms seems like 6.5k Ohms was about right. The wire then runs to your controller. If you had a controller to look at with a manual it might already include the specifics. And I'm not sure to the accuracy but hopefully that's gets you looking in the right direction.

I'd also like to be able to vary the regenerative braking as easy as I press on the power brake too. Removing the brakes on the driven wheels is probably out of the question whereas a motor might pull hp from generating electricity which creates "regenerative" braking I believe the power brakes generate more stopping power to the wheels. But I don't know. It's hard enough to get continuous power ratings from electric motors, manufacturers don't include rated stopping power with their factory brakes. Maybe there is a table on it somewhere.

And @evolutionmovement, why a manual controlled CVT? Couldn't you just run the engine RPM off the throttle(hold on while I explain this), the engine RPM that that the CVT maintains based on the throttle input. Eg, <50% it's in low RPM/FE range 50%-75% it's around the torque peak and above 75% it's trying to stay close to the HP peak? Maybe a little too much programming . Anyway don't pepper thread please. Now I've gone offtopic.

[aussie_modder]

I agree about he centering spring, it would take a bit of work to enable the throttle level to do this mechanically.

It would obviously depend on the intended use...
and the amount of electric assist desired when operating the ICE.

my thought would be to use the electric motor to drive up to 40 km/h (25 mph), then engage 5th gear wit the ICE, maintaining some electric assist to avoid lumbering up hills. Or one could start rolling under electric (say 25% duty), then accelerate as normal with the ICE (however beginning in a higher gear say 2/3), then reduce electric motor duty to 0% once cruising speed reached.

[Allch Chcar]

What motor are you considering? 35mph/60kmh is closer to optimum, you're probably not going to maintain electric power for very long and 35 should be enough for 4th gear at least. Some could probably hit 5th but conditions vary.

BTW, for future reference the only reason to use electric power to assist the ICE is when you've undersized your engine and absolutely need the power. It's just for safety when merging onto highways or for a burst of power(which isn't a design goal here). ICEs are more efficient under heavier loads such as acceleration and cruising speed. Where the electric works better is outside of the bell curve that the gearing gives your ICE but usually limited to the lower speed range. For an ICE that curve (thanks MetroMPG) doesn't hit good FE until the lowest speed you can power through the highest gear without bogging.

I think Daox and MetroMPG have stated this already but I just wanted to make sure you were on the same page, Aussie. Hopefully I have my credits right, if not, you know who you are...ah crud, who was it?