# One Motor or Two in a Classic Mini?



## scubaet (Jun 27, 2009)

Hello Everyone,

I am trying to plan out the motor placement in my Tiny Classic Mini and was wondering if anyone had suggestions on what would result in the most power for my car.

Car is a tiny original mini weighing in at a mere 1200 pounds. I would like to be able to get it to 60 in around 4-5 seconds and have a top speed of 90 Mph.

I was thinking of mounting the motor directly to a rear differential and ideally have the motor(s) in the middle of the car with axels to a front and rear differential making the car all wheel drive. (yes I know the benefits of retaining a transmission and clutch)










1) Is this something that is possible?

2) One larger motor (warp 9) or two smaller motors (6.7" or 8")?

(batteries and controller to be decided later)










http://chargedmini.com/


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## major (Apr 4, 2008)

scubaet said:


> what would result in the most power for my car.
> <snip>
> (batteries and controller to be decided later)


Hi scubaet,

You're asking power questions about the motor when it will be the batteries and controller (to be decided later) which will most likely be the determining factor when it come to "most power".

And the combination of battery/controller/motor power is pretty much independent of whether it comes from one motor or two or where they are located in the vehicle. Hopefully you can draw some opinions from this crowd, but it is up to you as to how you want to package your system and the components you choose to use.

I'd recommend a single motor choice for one's first conversion attempt.

Welcome to the forum and good luck,

major


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## rillip3 (Jun 19, 2009)

Direct drive is notoriously tricky and probably not worth the effort 99% of the time. You need a high mechanical advantage when starting, or you pull so many amps from the pack that you kill the batteries or the range. Then at higher speeds, you either over rev the engine or just can't put enough amps into it to make it go faster. Adjustable gearing is still pretty important to a car. While most EVs can get around town in second or third gear, you can't take them to 90 mph like that, or even 60.

It is easier to get power and acceleration out of two motors, because you can get two moderately high controllers more easily than one very large controller. However, one good sized motor, like a warp 9, will give you more than enough power to go as fast as you want in such a light car. Really an ADC 8" is probably more then enough if you get a high amp controller.

The controller is often the bottleneck. Make sure your batteries can put out the amperage you need and that the controller and motor can take it for impressive performance. You probably want > 500 amps if you can get it. You want a higher end voltage pack as well, so that you don't have to draw too hard on the batteries.

For a normal, drive around town at in town speeds with in town accelleration, I'd say you'd want a 72-96v / 400 A controoler / ADC 6-7". For 0-60 in 4 seconds you probably want 144v+, as high an ampere controller you can find, over 500 if possible (but not larger than your batteries can produce), and an ADC 8"+. Warp 9 would be very suitable for this. Warp 11 is not going to provide enough of a gain to make it worthwhile for the weight/space. Make sure you have room in the engine compartment to mount it too, you might want an impulse depending on dimensions.


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## scubaet (Jun 27, 2009)

Thank you for the detailed replies,

I did not realize direct drive was such a strain, but it makes sense. 

I think I will start off with one warp 9 mated with a mini or suzuki swift transmission in the rear of the car. this will also be much easier to setup / develop without having to do custom driveshafts, frame, etc. 

If that isn't quite enough speed and power I'll try out a second same motor / transmission in the front. (Twini Mini) Range is not an issue since my daily commute is only 5 miles each way. 144v with a 1k controller sounds fun.

While I'm waiting on some eaby auctions for the extra suspenison transmisison set, 

Do you know if anyone has ever run an ICE in the front and an Electric at the rear at the same time in a car? Provide unlimited range and increased performance. Would be interesting syncing thAe two poAwer sources though. I'm just rambling now so a simple good idea or bad idea is fine


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## Bowser330 (Jun 15, 2008)

scubaet said:


> Thank you for the detailed replies,
> 
> I did not realize direct drive was such a strain, but it makes sense.
> 
> ...


Why not stick the electric motor in the middle between the engine and transmission?

http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php

If you got the AC-15 (3200$) 46hp and 105 ftlbs extra...

Improved acceleration

Improved city MPG and freeway passing power in high gear (46hp available at around 2500-3000rpm)

System can regenerate power back into battery pack

A DC system could be used as well...for significantly cheaper...although no regen...and brushes will need replacing (albeit after a long while)


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## Qer (May 7, 2008)

scubaet said:


> If that isn't quite enough speed and power I'll try out a second same motor / transmission in the front. (Twini Mini) Range is not an issue since my daily commute is only 5 miles each way. 144v with a 1k controller sounds fun.


The motor will not limit you, the controller might and, considering the size of the car, the batteries probably will. A WarP 9" in such a small car will be rock-n-roll as it is, a second motor will only mean you can't stuff in as much batteries and will probably result in less performance rather than more.

A 1kA controller will probably be fun as hell in such a small car, but make sure the controller can limit the battery current or you might start to blow battery cells up...


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## rillip3 (Jun 19, 2009)

scubaet said:


> While I'm waiting on some eaby auctions for the extra suspenison transmisison set,
> 
> Do you know if anyone has ever run an ICE in the front and an Electric at the rear at the same time in a car? Provide unlimited range and increased performance. Would be interesting syncing thAe two poAwer sources though. I'm just rambling now so a simple good idea or bad idea is fine


There was a guy who just asked about that the other day, think his post may have slipped down to page two now. While it's obviously possible (it's basically what a hybrid does), there are some engineering hurdles to overcome which may or may not be possible for you. They're not possible for me, but I've the engineering prowess of a small child.

First, you have to keep the engine from driving the electrical motor so fast it over revs. Because the electrical motor takes up to 5000 RPMs, that shouldn't be too much of a problem unless you drive like a crazy person. 

But this all changes if you can't figure out the engineering bits! If your electrical motor is not connected to the transmission, it won't receive the benefit of the gearing, and could very easily over rev. If your gasoline engine isn't hooked up to the transmission, well, it's pretty well useless and just spinning until it gets to a RPM sweet spot. You can adjust that sweet spot with a gear box, but unless you put another full on transmission, you can only get an advantage out of it at a very specific speed range, and the rest of the time it's just an expensive generator. Plus, putting it in the back would require all sorts of mechanical and engineering gyrations.

In short, you can't put the engine in the back without putting a lot of mechanical work in, and it won't provide much benefit, other than charging the batteries. If you put the electrical motor in the back, you have to do a lot of mechanical work to keep the vehicle from blowing it up. 

I suppose you could set up the electrical motor on a medium-geared gearbox (say a siilar mechanical advantage to third gear) to keep the RPMs from blowing it up, and still get some benefit out of it. That sounds like the most feasible way. It wouldn't do much at high speeds and it wouldn't be the most efficient at slow speeds.

The rub is that the weight of the batteries, controller, potentiometer and motor already drive the car up about 400-800 lbs., even after the ICE is remove. So keeping a full sized ICE in there and putting all that stuff in will put you over the gvwr. 

You could get around this by putting in a smaller engine, since you have the motor to help out. But look at what you're doing; you take a reasonably fuel efficient engine, bump it down to a size that's too small, so it will have to spend more gas to give the same power, then add a bunch of weight for an electric motor.

While the hybrid vehicles coming out of Japan prove that you can make this work, the base premise is unsound. It would be more efficient just to get a more economic gas engine and leave off the weight of the electrical setup, or to go all electric and not carry around the weight of the gasoline setup.

So I think for the average DIY'er, a hybrid is a poor idea. But if you have the know how (or the dedication to get it) and the determination to make it work, the concept is viable.


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## MalcolmB (Jun 10, 2008)

Good to see someone else considering a classic Mini conversion. The compact layout makes it very challenging, but it could be a lot of fun. My own project has stalled at the moment as I've decided to save up and go for a larger lithium pack. The original idea was to fit two 7" motors in the front, each driving a wheel independently via toothed belt. My sums suggested a 0-60 mph time of around 8 seconds and top speed of 75-80 mph, using a 108V pack and 800A controller.

I'd agree with what the others are saying about fixed ratio being a big compromise. The only reason I was going with two motors is that I got them cheap. I reckon the simplest way of getting the performance you want would be to mate a single 9" motor with A Suzuki Swift gearbox, or similar, and drive the front wheels. It sounds like you're really keen to have rear wheel drive though, which means a lot more work. Here are a couple of links from the uk mini forum that might give you some ideas:
http://www.theminiforum.co.uk/forums/index.php?showtopic=30043
http://www.theminiforum.co.uk/forums/index.php?showtopic=28100
(the link to the 16Vmini club is temporarily down)

Let us know how you get on.


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## scubaet (Jun 27, 2009)

Wow thanks for all the responses!



> RE: Bowser330
> Why not stick the electric motor in the middle between the engine and transmission? you got the AC-15 (3200$) 46hp and 105 ftlbs extra...


Mid ev engined RWD was the original idea, unfortunately since I'm just out for the fun factor, instead of range, regen, and highway travel a DC is the better dollar value for me. It is good to see the price of AC coming down, last time I looked it was twice your links price.



> RE: Qer
> A WarP 9" in such a small car will be rock-n-roll as it is, a second motor will only mean you can't stuff in as much batteries and will probably result in less performance rather than more.


Going to start with one motor, will add a second in the future if budget allows to make it all wheel drive. Don't think just two of my poor 10-12 inch tires are going to be able to handle the power of the Warp 9  LOL



> RE: rillip3
> run an ICE in the front and an Electric at the rear at the same time in a car?


Great reply that took a lot of thought. Originally since I had planned on doing my conversion in stages I was considering mounting a ev motor in the rear with transmission. leaving it in 3rd gear. leaving the traditional ICE Engine in the front. Connecting both the gas engine and electric pot box to the gas pedal. Drive the car as normal and the electric engine would assist the gas engine by driving the rear wheels doubling the hp of the car theoretically. I'm sure its a ton more involved than that. After reading your post and reflecting on the thought of having explosive gas and 144 volts in close proximity is probably not the brightest idea!



> RE: MalcolmB
> Good to see someone else considering a classic Mini conversion. The compact layout makes it very challenging, but it could be a lot of fun. My own project has stalled at the moment as I've decided to save up and go for a larger lithium pack. The original idea was to fit two 7" motors in the front, each driving a wheel independently via toothed belt. My sums suggested a 0-60 mph time of around 8 seconds and top speed of 75-80 mph, using a 108V pack and 800A controller.


Glad you responded, was reading your thread the other day and sounds very interesting.

Regarding others conserns about cornnering issues, have you considered a setup like the following?



















Bolting the two motors together side by side and running the belt to the transmission (or suzuki swift transmission) similar to the second photo? (concept only, the second photo does not look efficient as it retains half the engine and crankshaft) This would allow you to run both wheels of the standard setup instead of independently thus eliminating the steering issues and still benefit from the power of both motors. I have not experience with these things yet just what I read from others until I get mine off the ground. 

And thanks for the links


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## MalcolmB (Jun 10, 2008)

Thanks for the suggestions. Yes, I've thought about doing it that way as well. I came to the conclusion that if I were to use a gearbox I would just use one of the motors. I'm not aiming for a high-performance machine, so my only reason for using two motors would be to ensure decent low-end torque in a single-ratio conversion. It's effectively a choice between two motors or one motor and a gearbox. It's the same as choosing between one large motor and single ratio drive, or one smaller motor and a gearbox.

In my case, the fact that I already had two motors made the single ratio option an easy choice, as it would eliminate the added work of making a coupler and adapting the gearbox linkage. Lately I've been leaning more towards the single motor and gearbox option though.

I've also considered a RWD setup, with the motors coupled together and mounted above a rear diff, driving it by toothed belt, much as in your first photo. That would mean a lot more work, but would also be a lot of fun. I'm a lazy bugger though, so I need to keep things simple if I'm ever to make any progress


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## COS (Dec 23, 2008)

Bowser330 said:


> http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php
> 
> If you got the AC-15 (3200$) 46hp and 105 ftlbs extra...
> 
> ...



Hey, just curious on the bolt pattern of the motors you linked above. Do they match up to the warp 9 motors?
________
Vaporizer help


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## Bowser330 (Jun 15, 2008)

COS said:


> Hey, just curious on the bolt pattern of the motors you linked above. Do they match up to the warp 9 motors?


From what i remember reading, yes they do. But I would confirm with them directly. With a system that costs that much, I would presume they would be very quick to respond.


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## ideabox (Jan 23, 2013)

scubaet said:


> Wow thanks for all the responses!
> 
> 
> 
> ...




Wouldn't it be much easier if you used the mini gearbox, covered the gearbox with an aluminium plate (silicone sealed for no oil leakages) & mounted the electric motor in the engine's place. Then instead of using belts or chains, make an adapter to fit the driver gear that used to come of the engine to the motor shaft.

I'm sorry I'm not an engine expert, just a good enthusiast. Been looking around the forum for ages & could not find something similar. Don't know, to me it just makes more sens & the torque should not create any problems as with chains or belts. Sry if I got the wrong terminology.

Ideabox


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## GREENHORNET (Dec 25, 2012)

scubaet said:


> Thank you for the detailed replies,
> 
> I did not realize direct drive was such a strain, but it makes sense.
> 
> ...


Many hybrids currently do this such as the Prius and Volt. I have not seen a lot of DIY builders attempting this. Most just stick with BEV for better efficiency. When you switch from power sources you lose efficiency and it does not work out in your favor. Most of the time it just makes sense instead of adding the electric components to just stay ICE. Besides where would you make room for the added electric components in such a small vehicle. Real estate space in that mini will be a premium! 

However with a smaller diesel engine say 3 cylinder 1 liter it could be possible. I have seen others do this and there are plans available on the internet that you can purhchase that show you how to do this. A while back I purchased plans from RQRiley who shows you how to build a diesel electric hybrid 3 wheeler. These plans would give you the knowledge and ability to adapt it to your mini! Here is the link = http://www.rqriley.com/xr3.htm i was going to do just this put in the end I decided against it because I would never take the car more than 40miles in a day. So why have the diesel engine and other necessary parts for the ICE powerplant. 

Besides it seems you have a minimal commute and really are geared for performance on this so why not just go BEV. I just posted to a guy who is converting a Fiat 500 similar in size to your mini and I suggested the dual motor route as a possible option. I would suggest it to you also for reasons all ready pointed out in the thread by others. 

A dual motor setup with the ME0913 PMAC motors would give you the ability to have great performance. they are 12kw cont 30kw peak @ 96V double them up and you get 60kw/80HP peak. I suggest them not because they will give you the best performance or because they are the best option but they are compact and lightweight being only 35lbs per motor. They can also be had for under $700 new and much less used. There are other similar options such as PMDC brushed motors Agni and Lees to name a few but at a much steeper price point! However they are even lighter at around 25lbs. 

So in theory you could have a 75lbs used motor combo for under $1000 that has the potential to put out 60kw peak power motor controller and battery depending. 

You can definitely go with a larger single motor design but at a weight and size penalty. Going with 2 smaller motors in tandem will save space cut weight and give you the ability to mount them either forward or aft easily. They are brushless in design so better efficiency and less overall maintenance. The only drawback is you would need to run 2 controllers such as the Sevcon Gen4 so cost would increase on this component compared to a dual series DC motor configuration that could roll with a single controller. 

There are always trade offs but that is the beauty of it. Keeping weight down would be my first goal. Getting the best bang for the buck on a budget would be the next. Save weight and space in all other places would allow you to pack on more battery weight for better performance further! 

Going dual motor would allow the possibility to cut out the rear differential for even more weight savings. Heck a single motor with a belt pulley system could cut out the rear differential and save a lot of weight if you had a descent transmission like the Coleman that only weighs 35lbs and priced new at $1,800 = http://www.colemanracing.com/Lightweight-2-speed-Transmission-P6179.aspx 

Or you could go with a budget used Powerglide modified but at a weight penalty compared to the Coleman. If you are trying to achieve 4 sec 0-60mph you need to make sure that the mechanical components can handle this power and torque. The Suzuki Swift/Geo Metro tranny and the Mini would worry me. The glide and the Coleman are made for it and have less friction compared to the Mini and Swift tranny options so this would also increase overall drivetrain efficiency which is a plus and should also be a design goal. 

You have a lot of options and a lot to think about so I will let you get to it good luck with your build  

GreenHornet


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## Duncan (Dec 8, 2008)

Hi Scubaet

I used to be a "mini guy" and I thought long and hard about converting a mini for my EV

Mini's - handle superbly - at low power levels
My 1430cc mini had 112Hp and was showing the limits of mini suspension
most of the upgrades - coil springs and the like make things worse

When I went for a 2 liter twin-cam (Fiat/Lancia - 175Hp) in the front I completely redesigned the suspension

If you want sub 5 seconds to 60 - ...
You will need a lot of power and better suspension

My suggestions
RWD with a diff in the middle, direct drive to the diff

Direct Drive --- Gearbox
You are talking about high performance in a light car, 
1000 amps in a 9 inch motor will spin the tires in top gear
What do you need a gearbox for?

In a small light high performance machine the additional weight and bulk of a gearbox is a big negative

In my car direct drive enabled me to put the motor in the "transmission tunnel" allowing the whole of the engine bay for batteries


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