Adding these electric motors to the back wheels of my FWD gas car?
 

I have a 2006 Impala SS. It is FWD and I want to add electric drive to the rear wheels. Since it is a big V8 in a FWD car, when you gas it hard, weight goes to the back tires, leaving the front tires without good traction. I'm sure you guys all know about that. Either way, it is a very fast car... once it gets going.


TL;DR
So I would like to put 2 of THESE motors in the back of the car- one on each wheel. This means that one would have to be set up to spin the opposite way, which the site says is possible upon request. They also have single-ended versions. So I'm just posting this here to see just how possible/viable it is to do.


My main concern is whether or not those motors can work together with each other, the gas engine in the front, and the car's transmission. Also, how reversing would work. I'm assuming the electric motor controller would tell them not to work, or to spin backwards, in reverse, but I am not sure.


If you are interested in all the reasons and the end goal, read on. However, most people can probably tell me if this is possible just from the TL;DR/



Here my full on goals and reasons:
Speed!
My engine has more torque(327lbft) than is practical in a FWD car, but I feel like I can solve that problem, and make my car incredibly fast, by adding these high torque motors to the back wheels. The primary goal is speed, particularly speed during the launch of the car. Once the car is in 2nd gear, I would like the electric motors to just stop, because they probably won't be helping after the car is over 50 mph, which is when the gas engine can really shine like it should.

So, if at all possible, I would like a controller for the rear motors that I can hook up to the car's ECU that I can set up to do that whole "turn off after 2nd gear", or 50mph, thing. I would use this in conjunction with a flash tuner for the actual car engine that would be set up for an open exhaust(courtesy of an electric cut-out, allowing me to go back and forth between stock exhaust and pretty much straight pipe) and all out speed. I would get this tune custom made by some pros at a dyno after the electric motors were installed.

Economy!
For this idea, I would like to use the flash tuner to force the car to stay in 4-cylinder mode(it has active fuel management already) and rev limit the 4 cylinder engine to 2200 rpm, which is how it is already limited. Trying to go above 2200 rpm in 4-cylinder mode will just re-enable 8 cylinder mode. Then I would use the electric motor controller to only enable the electric motors after the throttle is pushed beyond a certain threshold, like maybe 40%. The idea is that the electric motors will only help the 4-cylinder engine in acceleration BEYOND what 2200 rpm would allow. So I would find out the throttle % for 2200 rpm in 4 cylinder mode(lets say its 34%) and then I would tell the electric motor controller not to engage until the throttle is at 40%, giving me a little leeway before the electric motor kicks in when im cruising. I understand that I would probably have to then have the electric motors start at whatever ampage is necessary to accelerate the car organically at whatever speed I am going, which may be difficult unless the controller can have a different setting for each individual gear that the transmission is in.

Loose ends
I would like to have a decently sized battery, with maybe 20-30 miles or so of hybrid range, that I can charge up with power from the grid, allowing me to do all of this without having to load the engine, thus avoiding the whole "mechanical into electric back into mechanical" loop that would just make my economy even worse.

If the battery, which I assume will be in the trunk, ends up getting too hot, I will probably go with water cooling routed to a radiator in a wheel well(or both wheel wells, for double the cooling), assuming I find out that there is sufficient air speed in the wheel wells.. If not, then I'll suck it up and make a legit radiator in the front of the car for it.

I would also like to load the wheels on command, if possible, using a switch in the cabin or something. This way, if I had used all of my battery, but I wanna off my car's totally awesome launch ability, I could just drive around with the wheels loaded and charge the battery enough for a launch. Or, if I knew I was about to coast to a complete stop down a hill, which actually happens a lot for me, I could just flip the switch and get a little juice back. I am just assuming that automating this would be a little more difficult than is worth it, but I would like to have the feature.

Finally, the car needs to be able to go back to basically operating like stock at any time.

Summary
Speed mode: Open exhaust, super fast tune, electric motors on full blast from launch(or as much power as I can without them peeling tires), and then electric motors shut off at a certain MPH or gear.

Eco Mode: 4 cylinders, 2200 rpm limit, electric motors only for acceleration.

Stock mode: Obvious

Extras: A switch to operate the loading mechanism to recharge the battery. It would look nice next to the switch that would open/close my exhaust cut out.

SO, am I naive and foolish, or is this a viable project that I should spend my time/money on? Basically, if it is not too hard, I want to do it. As long as it doesn't cost more than ~$5k, money won't be the issue. Right now, I just need to know if it can work the way it does in my dreams.

Thanks!

For $5k, not gonna happen unless you get a screaming deal on all the parts. $5k will get you two motors and maybe a controller from the site you linked to (you'll probably need two controllers if you use two motors). Then you also need the battery (which could easily be $5k on its own) and however you're going to get the power from the motors to the wheels. Best way to do that would be using the rear drivetrain from a RWD or AWD car either based on the same platform or at least similar dimensions. Then you could hook up the motor to the differential (in which case you could just use one if its enough power).

Probably best left as just a dream unless you have a pile of money to burn.

A pile of money and a lot of time to spend figuring out how to integrate this auxiliary driveline with the stock electronics of your ride.

Ok, so how much would it cost, realistically? Under 10k at least? Can you guys recommend some batteries that I should look at?

Someone else recommended the motor-per-wheel approach over the idea of getting a RWD axle put in, but of course, a lot of people also recommended the RWD axle. The guy who recommended the 2 separate motors made his case by saying that the fact that I was keeping the entire stock drivetrain in tact meant that I could get away with not having the rear wheels hooked up to a differential and transmission, for reverse and what not. I could even get motors with no option to reverse, but they would need to be allowed to be "driven" by the main engine.

Also, do you guys maybe know if the performance gain would be worth it? If this electric car thing works out well, I would then proceed to get the front engine upgraded, as well as even trying to replace the 2 small electric motors with 2 bigger ones. If I had 2 motors in the back, providing roughly 400lbft of torque, along with a front engine with a turbo making around 400hp and a little more torque than that, would that really make the car brutally fast in a straight line?

I'm favorable to the flexibility of a hub-motors setup, but wouldn't object for a single motor driving through a rear differential since it doesn't increase the unsprung mass as individual hub-motors do. Also, you would avoid the need to compensate electronically the lack of a differential in curves.


Seems like you mean a thru-the-road hybrid setup, it's perfectly doable and even offered as a factory option in some European hybrids.

How about some stiffer springs? I'm imagining a stereotypical bouncy castle on wheels!

While the Impala SS is by no means a "sports car", it definitely has a decent suspension set up. Mine is about ready for new springs anyway, but the car rides much firmer than most stock sedans that I've been in. I've had people complain that my car is a bumpier ride than their Camry, Sonata, Malibu, etc., and therefore the suspension is not as good. Ha. It is also lower than a typical Impala and the spoiler actually seems to have a purpose at high speeds, even though I thought it was pointless on my car. Along with the bumpy ride, people use the fact that I occasionally bottom out on crappy driveway entrances as evidence that my car is not as nice as their cheaper, slower, smaller sedans.

Also, I wont be spending any time on a track. I'll mostly be at the drag strip. As long as it doesn't feel like a boat on the highway, I think it will be fine. I'll have to wait until all the added weight is there to really know though.

Interesting idea but honestly I think you are being totally unrealistic about what you can accomplish for under $10k, if I am understanding all that you want. Are you wanting to pull 400lbft torque from your electric motors in addition to your gas engine?
I will throw out some thoughts to consider, but please understand I have no first hand experience.
Did Chevy make your car with a 4WD option? If so, maybe you could find a parts car to adapt parts from. Are you thinking of having the motors direct drive to the wheels?
Do you have room to mount both motors end to end and still run cv driveshafts to the wheels? They can't be hub motors. I really don't think they would be the best motor choice anyway with all you want from them. One would be okay through a diff. but series motors don't regen. well which is on your wish list. Yes they have high torque on start up but if you run them direct, they will be running slow all the time and probably will overheat. I think controlling them to get even torque will be a nightmare as well. Series motors don't self limit their max rpm so if you ever spun a wheel on a slippery spot it could overspeed the motor and do damage. A single motor through a diff. would be easier and cheaper. The brushes will be wearing even when the motor isn't being used and if you do use a diff, you need to be sure you gear it so you don't over speed your motor at top speed. AC motors are much easier to control and will do regen, but will cost even more and finding low speed/high torque motors could still be an issue. If you lower your performance goals, you might be able to fit hub motors to the rear wheels but they likely won't have the torque you want.
When you are talking battery pack you need to pick batteries that can deliver the high currents you want as well as the range. Once again more power means more money. High quality lithium will be a must.
I think anything can be done with enough time and money, the question is how bad do you want this?

you must really, REALLY love this car!

If you want a unique car that'll probably be faster than any other FWD Impala SS, then go ahead and do it. Your first step should be figuring out how you're going to physically get power from the motor(s) to the rear wheels. Using the rear axle from another car and connecting the motor(s) to the differential is probably your best bet.

If you want the fastest V8 car for the money, you might be better off getting a RWD car. For $10k you can easily get a car that is faster than your car currently is, maybe even faster than it would be with the electric motors.

I totally understand that I can get a much faster car for not too much money, but I am trying to see if it is possible that I can make this car into something really special. This car has a V8 in it, which could be upgraded to get some good power, but then it just cannot put power down until about 40 mph. This car consistently chirps the tires if I floor it at under 40 mph, and it has nothing to do with the sheer power of the engine, and more to do with the fact that its FWD.

I am wanting to see if adding RWD power to it will remedy this situation. Once the car is going, it is definitely respectably fast, but its a joke off the line. If these electric motors can get the car off the line faster, then I think it can compete very well with cars that are naturally much faster, once the gas engine is also upgraded. I want to do this electric stuff for under 10k, because it will be around 7k to get the gas engine upgraded to putting out close to 500hp by itself, which is possible, but incredibly stupid in a car that is FWD.

The main thing that I'm asking is the price and the expected outcome. Will have 2 electric motors, putting out roughly 300lbft of torque(150 to each rear wheel), coupled with my gas engine, putting out(realistically) around 280 lbft of torque, make my car get to 60 mph all that much faster, or are there seriously limiting factors that make the performance gain not worth it?

Definitely! I am also a modder at heart though, so, once I get a different car, this car will most likely be a project. That is what this whole thread is about. I will hopefully own myself either a Tesla Model S, or a Chevy SS within the next few years.

At first, just to get things going, I would like to use the small, cheap motors to see if I can get them to work, as well as see if there is a noticeable performance gain. After that, assuming I am satisfied with the results, the real money spending starts, including buying more powerful electric motors and getting performance modifications for the gas engine as well.

No, and Yes.
My car is based off of the GM W Body platform, which has had no AWD or RWD vehicles. However, I have read about people doing RWD conversions on W body vehicles using rear axles from certain GM suvs, such as the Pontiac Aztec, which I may be able to find a rear axle of for very cheap.

If you mean perpendicular to the wheels, then maybe.... If you mean to mount them longways along the center of the undercarriage, then I seriously doubt it.

I managed to look at the underside of my car once while it was being serviced, and took some pictures as well. Do you think I can fit 2 small electric motors in this space? What are these things, and can they be removed? Do you think it will be difficult to connect the motors to the frame of the car? I am definitely not opposed to a new exhaust system to make it work. Also not opposed to losing my spare tire space if that will make the room that is necessary.

http://i823.photobucket.com/albums/z...pspe5cry0w.jpg

http://i823.photobucket.com/albums/z...pseacfuo3t.jpg

Now all of that is good info for me. Definitely haven't heard about most of those issues. Basically, here is how bad I want this:

If I have to completely mangle the undercarriage of my vehicle in order to try and fit electric motors along the center, to then go into a diff off of a random SUV, then it may not be worth it to me, just because that is only half of the work, and will be very expensive.
However, if there is any chance of getting this to work by mounting the motors directly to the wheels along the space that a rear axle would be, then yes, I definitely do want to do this. Remember that I can use the front drivetrain to do anything other than go fast in a straight line. The economy stuff is just something that I would like to do if possible. If it would make this whole project THAT much more difficult, then I would totally just leave the motor off until I got to the strip.

That being said, I don't actually know what is under that undercarriage cover. If I find out that there is room for 2 electric motors to be coupled to each other and run through a differential, and that moving the gas tank isn't as hard as I think, then I would totally do it.

The other option is using one single powerful electric motor that is double-sided to drive both wheels. This basically means I will have a locked differential, which may not be ideal, but then again, this car is going to be just for straight lines. I have already had a close enough call involving a slight curve on a long, high limit road, where torque proved to be a scary thing. I do not ever want this car to be over 3k rpm on an even remotely curved road. Basically, if I have to simply not use the electric part of the car if it is wet, or if I am on a gravelly road, then I wont.

Here's a video that made me consider using that particular motor.

That motor has about a 12 inch diameter, which means im pretty certain it can fit in that cavity. However, the reason I think 2 separate motors would be better, is because they will actually put out more power, while also having a smaller diameter. If the gas tank is in the way for the 12" motor, then perhaps it won't be in the way for two 9" motors. Then the question would be whether to couple the 2 motors into one, like in this video, or have them each drive a wheel by themselves.

They have a 13" motor that puts out much more power, but is also much more expensive.

Thanks a lot for your comments. I hope you can make more sense of what I want to do now, and, hopefully, tell me about how totally possible it is. :)

What things are you referring to?

In my opinion, doing the axle swap from an Aztek or similar would be the easiest way to connect the motor to the wheels (I use the word "easiest" loosely here). You're already going to have to redo your suspension and swap in hubs that can be powered. You'll probably need the gearing in the differential as well to keep the motor happy. It would probably be best to go all out on the motor, controller, and battery the first time. Cheap parts won't be a whole lot cheaper and there's not much that you could transfer from a low power setup to a high power one.

Don't forget to consider the horsepower the motors put out, the one you linked to in the first post is 38hp at 72v (not sure if/how much you can overvolt it). Torque isn't everything, a 100lbs person can produce 300lb-ft of torque just hanging on a 3ft breaker bar, but that won't rocket a car down the drag strip.


Have you done anything to try to keep the front tires from lighting up? A limited slip differential and sticky tires would help you get the power to the road as it sits and would be beneficial to have even if you do add the rear motor.

Pretty much everything in that picture that is not suspension, exhaust, or the gas tank. I have no idea what that stuff is for.

As for the horsepower comment, I have a V8 gas engine for horsepower. These electric motors put out over double the torque than horsepower. The BMW m3 from that video puts 850 lbft of torque to the actual wheels on a dyno, but only 342 hp. That is exactly what I want. Raw torque to launch my car because the front engine sucks at making it happen. Once the car is going, maybe around 70 or 80 mph, the front engine will continue producing torque and horsepower, while the electric motor will just be fading off.

The reason it is so hard to keep the front tires of lighting is because the car is not completely built for that, like, say, the new Honda civic type R. When my car launches, weight transfers off of the front tires and on to the back tires, leaving the front tires with less grip. Sticky tires would probably help a little, but even then, it wont be anything special.

Impalas are FWD?

Single speed electrics need about twice the torque for starting up compared to one with a [two speed] transmission, per EVTV. For instance my Lexus MGR would rev to 10,000rpm with 6.something reduction (after another $12,000 investment. :( ).

Frankly, since your going to be saving up for a while, by years-end they will have reverse engineered the CAN Bus controls for the Telsa drivetrain. 400hp. You could ditch the V-8 and have a faster car.

http://d2ojs0xoob7fg0.cloudfront.net...or-300x243.jpg

Sit through a few back episodes of EVTV and see what you think. It's on Youtube and at EVTV Motor Verks - Custom Electric Car Conversion Instructional Videos

Crossmember and brake lines?

Realistically this mod is too complicated. Its far simpler to just get a car with better mileage, or a car that you can do other mods on.

This, as described absolutely will not work for a few reasons.

1. These motors are heavy. Using them in an unsprung application would result in horrible handling and probably destroyed tires/rims from hitting potholes.

2. As has been stated already, these are low speed high torque. Good for a forklift. Bad for a car, unless you are going to use it as a yard tow vehicle.

I think there is a definite application for hub mounted rear wheel drive as an add on to something like a civic or a metro, primarily to give it hybrid capabilities, secondarily to give it 4x4 capabilities. Such a motor would be a high voltage AC motor with pretty modest power output.

If you want to make a large american V-8 sedan accelerate, it is simple physics. You gotta spin the wheels where the weight is, via that big lump that is already producing lots of power. Kinda like the way they did it the prior half century in impalas.

Get an electric motorcycle.

regards
mech

Get a bicycle! :D

for what you want I would look for ways to convert it to 4wd. You will get more power to the road and imho less weight penalty comparing to electric motor+battery pack+driver.

some 4wd subarus or hondas used viscous oil clutch to connect rear wheels to engine when slip occured. I am no expert, but this sounds like "plug and play" solution to me, as you do not need to mess with your car ECU, just connect it mechanically - so you should have less problems with connecting it.

Make it happen for around $5000? Can't have it.

The ImPulse9 motor you're interested in is $1800 already, so you're through two-thirds of your budget on motors alone.

While you're still blue-skying, the ImPulse9 can be had in either rotation. You'll just need to call NetGain and talk to them. And they're reversible in the controllers too, so you can have electrical reverse. But if you have the reverse gear in the conventional transmission, this is not important.

Cornering wouldn't be the only problem, the ABS sensors might bug out too.

You could try to find one of these.. https://en.wikipedia.org/wiki/Chevrolet_S-10_EV
There was an article in Grassroots Motorsports a few years ago who my an electric hybrid out of an old MR-2. Put one of theses motors in the front, found some Prius batteries and had an all wheel drive electric hybrid..

https://en.wikipedia.org/wiki/Chevrolet_S-10_EV#Sales

492 produced, possibly 60 that weren't crushed at the end of lease.

integration-schmintegration
 

On projects like this I'm not worried about synching up the electronics between engine management and motor control. The engine will behave like it's going downhill. (Just like operating my ICE pusher trailer behind an EV.) The electric rear axle could be completely independently controlled, preferably with a hand throttle, or if off the same accelerator pedal; through a master switch to enable/disable the Warp drive.

However, I think this car will be too difficult mechanically. On any car it is difficult to put one series motor on each rear wheel unless they are offset by using a gearbox, as there's not enough width for two motors, half shafts, and CV joints, let alone at the right angles. Putting a differential beneath a body that wasn't designed for it might be doable if you don't mind a big hole in the floor.
Also, this dual rear motor approach with one per wheel has been oft discussed, but very rarely implemented on a DIY EV. As I recall, the Tropica was then only series-motored 'production car' to do it, and not particularly well at that.
Polychain belts and their cogged pulleys are noisy.

I'd still love to french a motor into the driveline of a pickup one day. That would be much easier.

Could you link-ify that please?

I always enjoy seeing the yellow Ghia. What do you think of this?
http://ecomodder.com/forum/member-fr...mpare-size.jpg

98lb, 68hp. 10,000rpm single speed at 6.8:1.

When Arcimoto ships the SRK there should be replacement crate motors available. It has a similar single-speed drivetrain with twin motors on a common shaft. I haven't seen the power rating, though.

Thanks Freebeard, Is that VW engine case as rare as it looks? I'm guessing freshly prepped 25 hp/ 1100 cc?

Sure, here's some of the pusher trailer exposure.

Here's an article about the pusher and its creator from Popular Science, May 2007 issue.


I've since sent the Straubel pusher on to the Historic Electric Vehicle Foundation in Arizona and am trying to have my own version ready by summer.

The first 'successful' DIY hybrid I saw was a Subaru Justy with a forklift motor driving the rear wheels, which had been disconnected from the front. It was a fun hack- long since scrapped, I imagine.

"French" a motor in the driveline?

Kinda like this:
Technology | XLHybrids

There was also EchoDrive, but they appear to be out of business now.

That might be. It was sold to me as a 36hp case. From TheSamba.com :: View topic - Stone stock 36hp engine, what does that mean to you?
It's ID number is 3261377. It's got road rash on the sump fins but the mechanic who checked it over said it would need to be machined to take standard sized 36hp main bearings. So who knows. Some minor scuffing in the lifter bores.

After my first trip to Bonneville, I was interested in the 36hp Challenge. More lately I want to get a way from gas engines. But if I had an Arcimoto SRK, I'd probably start thinking about a half Vespa motorscooter pusher.

Adding these electric motors to the back wheels of my FWD gas car?
 

Hi Jay, Its good to see you here. I've been out of this stuff for a while. What ciano22 wants to do is totally doable. He even showed pic up under the car and all the worries I would have are alleviated.

First I want to state that I am not so up on joining yet another forum. Too many over the years got me too many house projects that have got me in trouble with the spousal unit. But EcoModder sounds like a cool one to me and right up my alley as a Certified Energy Manager.

Next I want to say that its good to see other EV (and NEDRA) guys on this forum. If there EVer was an ecomodder it has to be an electric vehicle guy. Maybe Jay has told what he gets for GGE. For me its about 100 MPG on my truck. But thats an analysis based on current cost of gas. Price of gas goes up my GGE goes up too :-)

And now to get to ciano22 project. Its totally doable. I'm going from memory but I thought you said the Impala makes 327 ft-lbs torque. And that you want more than that to the rear wheels to get the car moving. I can tell you than my 1978 Pinto with two WarP 9" motors puts 1500 ft-lbs to the Dyno. That is likely way more than you want to put what I think your desires are. So don't be sold on bigger is better and try to stick 11" motors up under the rear end.

9" motors may be more than you are looking for. And for your budget doing dual 9's will put you slightly over your $10k budget because you also have to consider the motor controller and batteries.

Now for batteries you don't really have to go too big because you are just wanting the motors for accelerating from slow speed. Aside from what many might think it does not take that much energy to accelerate a car to 60 mph compared to what it takes to just drive it for 10 miles (at that same speed). Think about it 180 HP for 15 seconds compared to 10 HP for 600 seconds. Although not really a unit of measure, it is in my mind. 2700 HP-seconds or 6000 HP-seconds. Its the same amount of energy. So you say the car makes plenty of HP at speed. That means it makes enough to slowly charge the 2700 HP-seconds you wasted accelerating at a high rate over the next few minutes. So really the Hybrid approach is a good idea. And it works the same way for other hybrids.

So the question you have to ask is how much "extra" torque do you need? As I said my twin 9" motors make 1500 ft-lbs. Although torque tapers off quickly with RPM, that's where a good string V* just getting up into its HP band would be useful.

If you want 3000 ft-lbs go with dual 11" motors.
If you want 1500 ft-lbs go with dual 9" motors.
If you want about 1000 ft-lbs go with dual 7" motors.
You could probably even get 600 extra ft-lbs with dual 6.7" motors salvaged directly off an old forklift.

The problem with the "differential movement" fixes itself with two motors wired in series from the same controller. Imagine if you were to mount two motors on top of a straight axle of a front wheel drive car. Put a gear inside the hub and mount a series would DC motor to it with about a 3:1 gear reduction. With the motors in series they will always have the same amount of current (and voltage) when they are turning the same RPM. BUT, if one starts to slip and the RPM is faster, the back EMF on the motor will drop. The other motor with the slower RPM and higher back EMF will have a higher power split from the batteries. With the same current flowing through them, the motor with the higher Back EMF on it will pull more power. Higher back EMF X same current is > than Lower back EMF X same current. So its a natural Differential action.

So the long and short is that what ciano22 wants to do is readily possible. You just have to figure out how to mount the motors to an axle that connects the two rear wheels. If as he says he wants to start with smaller motors he could do that. Two 6.7" motors cost $600 each. A Zilla 1K costs $2k (I think - its been a while) and 30 XE-16 lead acid batteries cost $3k (LiFePO4 would cost more)(but there are other more power dense Li- based batteries that would be suited to just jump starting). I have the idea on how to do that if he wants to contact me off list. I won't share the details until we get a working model, which I have been thinking of doing lately on my 7.3L Powerstroke Diesel. :-)

The guys at NetGain which makes the WarP motors have a kit for that by the way.

Cheers
Mike

That's interesting. Is the 'natural' differential action proven or theoretical?

I'm not so sure about DC motors and lead acid batteries. The Warp 9 graph shows ~12 to ~28hp. How much does it weigh?

Here's a water-cooled 20hp polyphase DC altermotor that costs $512.32:

24266687 - OEM GM GENERATOR GMPartsCenter.net

http://dz310nzuyimx0.cloudfront.net/...b7f96ae88e.png

It wants 115 volts. Instead of hanging two Warp 9s on a beam axle: Two of the Buick/Impala part mounted at one pivot of a swing arm with the 7-groove V-belt to the axle. Un-sprung weight would go way down. First 'gotcha': belt tension might affect wheel alignment.

ZF have shown a twist beam rear axle with geared reduction:

http://www.zf.com/global/media/produ..._pf_teaser.png
http://www.zf.com/global/media/product_media/cars_5/cars_chassis_etb/ZF_cars_eTB_PF_corporate_pf_teaser.png

Maybe the Buick belt drive could be replaced with a gear reduction.

Edit: That equation has two sides; I pay 5.3¢ per kilowatt hour. If I go across the river to the next town, it's ~10¢. Anyone who finds themselves on the Eastern coast of this great country will pay ~15¢ for electricity rolled from coal.

https://www.youtube.com/watch?v=5vLZOKshJPs

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Post #5 now I can add links :-)

Adding these electric motors to the back wheels of my FWD gas car?
 

Although I haven't seen any research papers on the subject with respect to this application, I can prove it to you. Or you could prove it to yourself. Go get two small DC motors. Little ones like you find in a cheap kids toy car. Wire them in series across a 6V battery. They will both start spinning about the same speed if they are the exact same motor. Then grab onto one motors shaft and slow it down and you will hear the other one speed up. You could go even further and totally stop the one motors shaft. Although the torque will increase on this motor, the other motor will spin a lot faster. Just remember the current will always be the same through the series circuit. The motors will share their voltage in direct proportion to their speed.


Warp11 weighs 243#
Warp9 weighs 143#
Warp7 weighs ~100#
A 6.7" motor weighs ~67#

Be careful in reading the Motor Torque RPM charts. They can confuse you if you are not familiar with all the test conditions. For example the torques shown will be at a certain speed with a certain load on the shaft. For accelerating from a stop try to find the locked rotor torque and it will be extremely high. And as the RPM on the motor rises the torque will slowly drop. And as Jay said it will also work naturally with the gas engine taking up at higher RPM as the torque on the electrics drop to almost an insignificant contribution.

Dyno results for my Pinto are here http://www.dragtimes.com/1978-Ford-P...phs-15453.html

Other details here http://www.dragtimes.com/Ford-Pinto-Timeslip-15453.html

and here Mike Willmon's 1980 Ford Pinto


Yes adding these motors to the beam axle will increase unsprung weight. Which is I would advise not to go with a WarP11 motor, thats way more than is needed for the desired outcome. I might argue more for a 6.7" or the WarP7 (which is 7.25"). Mounting right to the axle would allow coupling to the hub with a gear set or a 50 roller chain. Tension would be taken up in its mount and would not change with position of the axle.

We (royal wee) like papers, but A-B-A testing rules.

But can it do torque vectoring? FOC motors are persnickety about their phasing, but once that is accommodated in software, torque vectoring becomes possible.

My understanding was that it rises until the back-EMF kicks in and it flatlines. Maybe that's the polyphase motors again?

The weights don't seem out of line, but putting one on a clutch and transmission sounds counterproductive to me. This single speed installation would be better. EV West just did a conversion on a Fiat 124 and immediately made the clutch disk into two parts. Gas motor drive trains don't expect the microsecond shock loads.

Tesla doesn't do it. Arcimoto doesn't do it. But, Wolftronics make a 2:1 planetary gear box that will pass 500hp.

*Take all this with a grain of salt. I'm still gathering parts and info for my first EV conversion, as thingstodo can attest.

As I mentioned in another thread, it's about RPM range. The poly-phase motors production EVs run can do 10 or 12,000 rpm. These DC motors are limited to 5 or 6k. The production EVs run ~10:1 final drive. If you did that with only 5 or 6k peak, you'd only be able to drive around town. If you cut the ratio in half, you'd kill your acceleration, or else require a hell of a lot more amps to make it acceptable. Which means a bigger motor and a bigger controller. More weight and much more $$.

So lets say you do it anyway. You're now running twice as many amps on take off. Amps = heat. And heat = inefficiency. Your efficiency goes to hell at low speeds. Compounded if you use lead acid batteries. (I believe, back in the day, the rule of thumb was that that direct drive cut your range in half.) Worse....your motor is air cooled by a built in fan that's driven off the motor itself. It's not spinning fast enough to shed regular levels of heat, let alone the extra heat being made by all those extra amps. You'll either have to add force air-cooling, or risk overheating and killing your motor. Half the reason for running a bigger motor is the sheer mass of copper...more thermal mass to absorb all that heat.

Heat in a production ev motor isn't nearly as big of a worry. They're liquid cooled, independent of motor speed. They have that 10:1 gear box, so they're not "lugging", and they only require half (or less) as much torque to get the same results. They're also more efficient at low rpm, so there's less heat to begin with. All-around better. That's what happens when things are purpose-made for their application, I've noticed...

Speaking of purpose-made...there's a 2-speed powerglide transmission out there for EVs, sans torque converter. Plenty strong enough, and gives you that gear ratio change you want to go with DC motors. Not cheap, though. Perhaps one could convert an old powerglide for a lot cheaper?
Powerglide 2 Speed Direct Drive Transmission for EV Motors - EVGlide, EV West - Electric Vehicle Parts, Components, EVSE Charging Stations, Electric Car Conversion Kits

And, before I forget, you want to also note the torque curves of series-wound motors.

http://www.go-ev.com/images/003_15_WarP_9_Graph.jpg

Due to the self-weakening field nature of series-wound motors, you generally start to run out of torque above a two or three of thousand RPMs(vs an AC motor with a pretty flat torque curve). To get more torque, you need to cram more amps in to it, and the only way to do that is to overcome the back EMF with a higher voltage. If you don't...well, 5 or 6k rpm might be your motor limit, but it becomes useless well before that. You'll never get up to speed that way.

IMO, these Netgain/DC motors are designed to replace an ICE directly, and they work well when used as such, but for other applications, there are better suited motors.