# All Wheel Drive for EV Racing Applications...



## DavidDymaxion (Dec 1, 2008)

I think these guys have been most successful at it:
http://www.proev.com/

They are AC, but I don't see why DC wouldn't have worked.

Note that there are many very fast, successful race cars with RWD. It takes an inordinate amount of power to exploit AWD (about 300 hp in 1st, 450 in 2nd, 700 in 3rd, 1000 in 4th), otherwise the lighter RWD will be faster. All that presumes dry pavement, on dirt or snow it's a different game, there you do see AWD dominance.

What is really awesome is with A123 Systems batteries you can make enough power that you could really exploit AWD. Good luck finding an AWD driveline tough enough for 1000 hp, though!


Supreme1906 said:


> What might be the best/most practical all-wheel drive transmission system for a dual DC motor setup? It seems logical enough to me that if you have all that torque available, you could see some amazing results with all 4 wheels pulling...
> 
> I'm trying to conceptualize a project I might want to undertake, but my ambition outweighs my expertise in this area. Any thoughts? For the purpose of this exercise, forget cost.
> 
> Thanks...


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## aeroscott (Jan 5, 2008)

Honda transverse mounted trans with custom half shafts . All built with race grade parts . AC, Tesla , Ford Ranger EV etc all use the transverse layout .


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## Supreme1906 (Jun 4, 2009)

That's the question that inspired this whole thing. Even Tesla couldn't solve this issue without much difficulty, so I wondered how could I with my finite budget. Even the Veyron's tranny is purported to handle only 1100 ft/lbs of torque, much less the 1700-2000 some EV motors could put out.

However, its funny you should link me to that site, because I was thinking of setting one motor to the front wheels, and the other to the rear. They do seem to have had some success with that set-up, so at least I know its feasible...

Thanks.


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## Bowser330 (Jun 15, 2008)

well the racer in the link isnt using a transmission, hes using two open differentials...so...that could be an issue if you plan to go DC..

So if you plan to use DC like me, siamese is my only shot...


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## CroDriver (Jan 8, 2009)

Supreme1906 said:


> That's the question that inspired this whole thing. Even Tesla couldn't solve this issue without much difficulty, so I wondered how could I with my finite budget. Even the Veyron's tranny is purported to handle only 1100 ft/lbs of torque, much less the 1700-2000 some EV motors could put out.


The Veyron had had problems with the gearbox. It's a high-tech 7 speed DSG gearbox with a double clutch. It's very sophisticated and that's why they had problems with the torque.

I think that there are differentials that can take easily more than 1000 nM (the Veyron has 650). Some firms are producing custom differentials for racing applications so we could make our own with the ideal gear ratio for us.


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## CroDriver (Jan 8, 2009)

Bowser330 said:


> well the racer in the link isnt using a transmission, hes using two open differentials...so...that could be an issue if you plan to go DC..
> 
> So if you plan to use DC like me, siamese is my only shot...


I'm currently in a siamese 11" Kostov project on the rear diff (Mazda RX-8) but my plan is to make a double-siamese with AWD when this project is done.


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## mjcrow (Jan 5, 2008)

Direct drive to 2 of these http://www.dutchmanms.com/1_irs_centers.html (1 in the front and 1 at the rear with the same ratios) should handle pretty much anything you can throw at them, but you may have to run the front diff upside down to fit it, depending on your choice of vehicle. Maybe Subaru WRX , Mitsu Evo, Celica GT4, Porsche Carrera 4 . All will need substantial work to fit the rear motor (except the Porsche ), i.e. cutting the floor and adding structural members to take the motors weight and loading.

Not impossible but expensive, and you did say forget cost!


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## Supreme1906 (Jun 4, 2009)

I might be able to score an '06 Mustang for next to nothing. (I could barter it from a friend in exchange for services I am already providing his firm.) So that's the car, and I was aiming for the specs of the Ronaele 300/600E. But I didn't want a simple drag racer. I wanted an electric car with that could perform more like a GTR. I mean, this would be my first electric build so I wouldn't be swinging for the fences, but I wanted to at least do something a little different.

I was definitely thinking of independently powering the front and rear ends, but how would connecting the motor directly to the differential affect everyday driving and/or street legality? Further, is a transmission even necessary for electric applications, provided you are using custom differentials?


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## mjcrow (Jan 5, 2008)

If it's a '06 Mustang then my 2c would be to forget 4wd, the chassis isn't designed for it and making room for driveshafts to run and finding suitable hubs/suspension could be problematic. But don't despair, a '06 stang can be built to handle quite well, aftermarket parts in that area are off the shelf. 

To match the 600E you need 2700Nm and 450Kw (they use a DC motor), which is really up there performance wise, maybe Major or the other gurus here could help out with what is available to match those specs (Custom 13" maybe and Zilla2K). 

Mounting direct (i.e. without a gearbox) isn't a problem as long as you have enough torque and power. If you really must go with 4wd on the "06, then you need to talk to an engineer and find out what's possible (and legal) and at what cost.

Here is a '02 Stang Electrified http://www.diyelectriccar.com/garage/cars/47


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## Bowser330 (Jun 15, 2008)

Seeing as the Electric motor is much more compact than the ICE Its replacing, if you were get the front suspension of a FWD Ford, Im pretty sure it wouldnt take THAT much fabrication work to make it fit...so you could have FWD and RWD...

With higher voltage through a DC motor (Kostovs can handle up to 300+, Warps are up to 192V I think...) the power band of the DC motor is stretched out over more rpm...


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## Supreme1906 (Jun 4, 2009)

I came across this team of HIGH SCHOOL kids in Philly who built a Hybrid "supercar" that had an AC propulsion electric motor powering the front wheels, and an VW TDI bio-diesel engine powering the rear wheels. I'm not suggesting that this set-up would necessarily work in a Mustang, but it does lend credibility to the idea of independantly powering the front and rear ends to optimize power distrobution. Check the site here:

http://evxteam.org/index.php?option=com_content&view=article&id=2&Itemid=25

They eventually had to remove the electrical drive components due to budgetary constraints, but the logic was sound. I figure 8-9 inch motors could me made to fit at both ends without too much effort at all, compared to the benefit you'd get from all that torque...


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## subydoored (Jun 8, 2009)

if you you tube the the jdm nissan skyline gtr those guys are pushing 1200 hp and around 1000 torque on an awd tranny. that transmission should take the abuse you want to give it. a subaru sit 6 speed will take 600 ftlbs torque to the wheels before it melts you could also buy a subaru dog box for about 8k and it would do want you want.


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## Supreme1906 (Jun 4, 2009)

Thanks. I did see a few all-wheel trannys that were used on high-torque engines, but none were without reliability issues. From what I gathered, the tranny on the GTR is only good for a few outings with the stability control off. Further, I learned in this forum that trannys on EV's aren't even necessary given the proper controls, so...

After doing some research, I think I want to try 2 AC motors, one mounted transversely in the front, and the other mounted longitudinally to the back differential to achieve that all-wheel drive i'm looking for. 

With this set-up, I could have the controller programmed to put all the power to both motors for racing situations, but switch between back and front for everyday driving, and efficiency purposes, like the 2-drive mode system in the Karma. Does this sound plausible?


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## CroDriver (Jan 8, 2009)

Supreme1906 said:


> Thanks. I did see a few all-wheel trannys that were used on high-torque engines, but none were without reliability issues. From what I gathered, the tranny on the GTR is only good for a few outings with the stability control off. Further, I learned in this forum that trannys on EV's aren't even necessary given the proper controls, so...
> 
> After doing some research, I think I want to try 2 AC motors, one mounted transversely in the front, and the other mounted longitudinally to the back differential to achieve that all-wheel drive i'm looking for.
> 
> With this set-up, I could have the controller programmed to put all the power to both motors for racing situations, but switch between back and front for everyday driving, and efficiency purposes, like the 2-drive mode system in the Karma. Does this sound plausible?


It's possible but you won't find any high performance AC sytems over 60kW. And you will probably have a weight issue.

I wanted to do the same thing:




Take a look at this:

http://www.evcomponents.com/ProductDetails.asp?ProductCode=AC55

and contact Dave [email protected]

May be he has some more 90kW AC systems left. I purchased one


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## Supreme1906 (Jun 4, 2009)

Nice. Thanks for that pic. That set-up is exactly what I had in mind. My only concern was whether the rear seat would have to be removed to accommodate that rear motor, which is why I re-positioned the front motor.

What was your rationale behind wanting to do a build that way?


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## subydoored (Jun 8, 2009)

if its the bmw the motor may fit in the area of the gas tank. dont forget that diffs also have there limitation.

you could bypass the diffs all together and just run 4 motors.


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## CroDriver (Jan 8, 2009)

Supreme1906 said:


> Nice. Thanks for that pic. That set-up is exactly what I had in mind. My only concern was whether the rear seat would have to be removed to accommodate that rear motor, which is why I re-positioned the front motor.
> 
> What was your rationale behind wanting to do a build that way?


I wanted to build a very very powerful electric car. 

There are a lot of advantages of such a lay out:

- No problem getting all the power on the ground

- Regen on all wheels

- If one system fails there's still one left

- weight distribution

- two total independent systems if two controllers and two battery packs are in the car

Since I couldn't get a AC motor that was powerful enough (I wanted 2X 200kW) I stopped this project.

Now I'm making an dual 11" DC Kostov motor, Zilla HV controller, ThunderSky LiFePO4 battery pack in a Mazda RX-8.

The motor will be connected to the rear diff without gearbox. This should be about 300kW electric power...


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## jb_elec (Sep 9, 2008)

CroDriver said:


> I wanted to build a very very powerful electric car.
> 
> There are a lot of advantages of such a lay out:
> 
> ...


Tell me you have pictures of this. I really dig the rx-8 and have thought about converting my own.


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## CroDriver (Jan 8, 2009)

jb_elec said:


> Tell me you have pictures of this. I really dig the rx-8 and have thought about converting my own.


No, I don't.

First I wanted to build the components in my BMW but now I want a better looking car. I will buy a Mazda in a few weeks. I'm still waiting for my components to arrive.

Here are some pics of the BMW that I wanted to convert:

http://www.diyelectriccar.com/forum...-moto-ev-project-28287p2.html?&highlight=moto


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## Jokerzwild (Jun 11, 2009)

This is what I am trying to do with a 914 Porsche but with 2 8" I will continue to watch you so I can learn!


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## Bowser330 (Jun 15, 2008)

so with two 8's you will have a setup like john wayland...

the benefit of the kostovs that crodriver is using is that they can handle upto around 300V without having any dangerous electrical arcing....

I am not sure two standard 8's can handle that (thats what im assuming you have)...

John W's two 8s are modified to handle such voltage and they only really are applied it towards the end of his quarter mile run...

What controller(s) were you planning to use with your two 8's?


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## Drew (Jul 26, 2009)

I'm not much good with the electrical side of things, but I can help out with some advice for your drivetrain layout etc.

I can tell you that having a bevel drive system will cost you fairly significantly in terms of driveline efficency, it would be best to go for two front wheel drive gearboxes and run one motor the opposite direction to the other.

I'm going to go out on a limb here and say that if you were running differentials only that there would be enough space where the fuel tank and differential subframe assembly usually go in a car to install a motor and differential from a front wheel drive car, possibly even a gearbox as well if you wanted.

As far as the benefit of it goes however it depends pretty heavily on the type of racing you're doing. If you're doing drags then there would be a massive point to running an all wheel drive system, but if you're competing in circuit racing then its very rare that a vehicles ability to put down drive is limited by traction. The reason for this is because a vehicles ability to put down power is proportional to its speed, the faster you go the more power you can put down, so if you're already going quickly then you won't benefit significantly from all wheel drive.


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## Bowser330 (Jun 15, 2008)

Drew said:


> ... it depends pretty heavily on the type of racing you're doing. If you're doing drags then there would be a massive point to running an all wheel drive system....


If you read the begining of this thread you would see this was a pretty debated topic...Does AWD really help if the overall weight of the car will be pushed back, therefore relieving the front tires of much need for traction....????

13" DC motor @ 320V + 1000A running through an AWD application should make for a fun experience...


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## Drew (Jul 26, 2009)

Bowser330 said:


> If you read the begining of this thread you would see this was a pretty debated topic...Does AWD really help if the overall weight of the car will be pushed back, therefore relieving the front tires of much need for traction....????
> 
> 13" DC motor @ 320V + 1000A running through an AWD application should make for a fun experience...



I was meaning in a more application based sense, because cars don't transfer a lot of weight front to rear AWD really helps out when you're talking about off the line, low speed or low grip situations. thats why AWD does so well in rally and that sort of thing.

On the other hand (for an ICE car) AWD is totally useless and in fact a hindrance above speeds where you can put all your grip to the ground. The reason this is is because you can adjust mid corner balance more easily with RWD than with either AWD or FWD and in the case of FWD the only way of achieving a more neutral attitude is to back off the throttle and let the car come around. This is why most circuit racing cars are 2wd (that and rules in a lot of formulas).

With electric you get the benefits that distributing the powertrain around the car doesn't hurt your drive efficiency and that you can regeneratively brake from the front motor set more than the rear.

If somebody were willing to put the time in then making a system that automatically balances drive to provide a natural balance etc to simulate a biased 4x4 system by using microcontrollers or similar to control throttle inputs would be seriously beneficial if you were talking racing AWD, but unless you went to that length I think in most types of racing it would be more a hinderance than help.

To take your example of a 320kW drive system, in a car with the ability to transfer 1000kg over the rear axle during accelleration (virtually any large sedan) you can put down that power at about 120km/h


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