# Which motor to choose?



## Max57TBird (Mar 22, 2010)

My donor car is a Bradley GT II, on a VW Bug chasis. I am shooting for a gross weight of about 2800 lbs. The car will be driven mostly around town, with some infrequent freeway use, about 30 miles max between charges. I am using sealed lead-acid batteries, at 96 VDC. I have a Zilla Z1K-HV w/ Hairball Option A controller.
I am comparing a series 67 D&D motor with the Warp 9, and of course one supplier says that I will be underpowered with the other guy's and the other one says that it will be overkill and a waste of about $850 USD (Incl. adapters). My research says that I could be satisfied with the D&D, but tickled pink with the Warp 9. But I can swallow a lot of pride for $850 ??????
Can anyone shed some light on my problem from his own experience or provide other sage advice for me ?


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## major (Apr 4, 2008)

Max57TBird said:


> I am comparing a series 67 D&D motor with the Warp 9..........Can anyone shed some light on my problem from his own experience or provide other sage advice for me ?


Hi Max,

I have never seen someone complain about having too powerful a motor. On the other hand, we see posts about the 6.7 motor being underpowered and/or running hot in full size conversions.

major


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## AmpEater (Mar 10, 2008)

After running a riding lawnmower conversion with a 6.7" for over a year, and even getting it smoking once or twice under abuse, I no longer think a 6.7" is adequate for a road going conversion.

But it will move a car.

I don't know about you, but I like to think "I'll buy the cheaper one and just take it easy".....then reality happens and I never want to take it easy. 

I'd go 9" and worry about something else


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## toddshotrods (Feb 10, 2009)

I say go with the Warp 9 too. I have an 11" GE going in my street rod, and just picked up a 6.7" GE to do an e-bike project. Just looking at and handling the two motors, there is no way I would want to try and push 2800lbs around in normal driving conditions with the small motor.

Building things that are just enough to do the job is for big manufacturers with multi-million dollar project budgets. Even with that, look at all the recalls when those precisely engineered parts and systems meet conditions the engineers didn't think of. In hotrodding, we over engineer to allow the proper safety/convenience margin. Even if you never use its full potential, that Warp 9 is probably never going to complain about a single thing you ask it to do in your EV.


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## Guest (Apr 18, 2010)

Go with the 9" motor. The biggest problem you will encounter is heat in that little motor. On the occasion you will want to venture out onto the freeway you will have a motor that will deliver. I use a 9" GE motor in my Ghia. With 96 volts and using a max 700 amp controller and flooded batteries I can push that car to 85 plus on a full charge. It jumps to freeway speeds fine. Not a quick racer mind you but it I always go on the freeway into town and back. 

The motor I have came from a Bradley GT II. It is an original motor from one of the Electric versions of the Bradly GT II. The motor comes with a built in adaptor. You retain the clutch. Do not do your VW clutchless with 96 volts. Being a lighter weight car you should do much better in quickness and speed than my Ghia. That Zilla will be a big help too. Don't expect too much in distance but it should do fine for most of your in town needs. 

Pete


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## EVfun (Mar 14, 2010)

The buggy in my avatar is running a 7.2 inch Prestolite motor. I can't get it more than just warm in 20 miles, but the buggy only weighs 1400 lb. The Bradley will be a little heavier and you are shooting for a longer range. I would still use a 7.25 inch Prestolite into your application if one was available. In new motors, I would choose either an ADC 8 inch, or possibly a WarP 7 or Impulse 9. I don't think you need the power handling ability of a full length 9 in a light weight VW kit car. I think you need about 110 lb. of motor since the weight of a series wound motor is a pretty good indication of its continuous power rating (I'm sure there are exceptions to that rule of thumb.) You also need one that can take the peak current you have in mind (up to 1000 amps.)


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## Guest (Apr 18, 2010)

I would say that a good 7 1/2 Prestolite woud do you just fine IF you can find a good one.
I would also say that the extra weight won't be as big of a deal as you might think. Also having a bigger motor does not mean you need to push to the limits but you will have that extra when you need it like a fun light to light run for fun or to scoot out of the way of an idiot driver. It is always good to know you have more at your disposal. I am going to be putting an 11" kostov in my buggy.


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## EVfun (Mar 14, 2010)

What makes you think the 11 inch motor will have "that extra"? Motors just convert watts into shaft horsepower. While it is true that larger diameter motors tend to make more torque per amp that is because they make less rpm per volt (the Impulse 9 is an exception to that, its graphs indicate the torque is more like an ADC 8 inch motor.) If you have less rpm per volt you are more likely to be a gear higher to get the speed you need and so you give it back with less torque multiplication. With the aircooled VW gearing (either 4.12 or 4.37 R&P with wide ratio gears) more torque seems less important than more rpm. You got the gearing to make all kinds of torque.

While very fast EVs may need larger motors to handle the abuse, larger motors don't make faster EVs. 

I've noticed a real escalation in motor sizes over the last few years. The 5300 lb. Red Beastie Toyota pickup with 40 golf cart batteries only ran a single ADC 9 inch motor (that was pushing it.) EV source has some vehicle weight motor selection information in the NetGain motor section.


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## Max57TBird (Mar 22, 2010)

gottdi said:


> I would say that a good 7 1/2 Prestolite woud do you just fine IF you can find a good one.
> I would also say that the extra weight won't be as big of a deal as you might think. Also having a bigger motor does not mean you need to push to the limits but you will have that extra when you need it like a fun light to light run for fun or to scoot out of the way of an idiot driver. It is always good to know you have more at your disposal. I am going to be putting an 11" kostov in my buggy.


Thanx Largely guys for the replies, deapite some favorable points ootherwise, it appears that the 9's have it.
However, Gottdi, if you are wanting to replace your Bradley motor, make me an offer I can't refuse. I tried PMing you, then emailing you but don't think either one of them went through, so am now trying this.
Lane


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## Guest (Apr 19, 2010)

Did you look in your PM? I thought I responded. If not I will do so again. Maybe it was email I responded to. Check.


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