# Motorcycle motor



## mrmeseeks (Jun 14, 2014)

I am looking to do a motorcycle conversion and so far I have been looking at HPEV AC-9 and AC-12 motors. I was wondering what other companies people on this forum would recommend with about the same amount of power. I have seen mars come up a lot. I was also wondering if you agree with my calculations that on flat ground either of these motors should be able to achieve a top speed of 100 km/h (about 65 mph) on a motorcycle, I have been having some trouble actually pinning down the HP values for these motors.


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## dougingraham (Jul 26, 2011)

From the HPEVS dyno tests found at hpevs.com

The AC-9 on 48 volts peaks at 27.75 HP at 698 amps at about 2200 RPM.

The AC-12 on 48 volts peaks at 19.23 HP at 650 amps at about 1300 RPM.
The AC-12 on 72 volts peaks at 37.4 HP at 576 amps at about 2200 RPM.
The AC-12 on 96 volts peaks at 44.92 HP at 563 amps at about 2700 RPM.
The AC-12 on 144 volts peaks at 65.37 HP at 431 amps at about 5400 RPM.

But horsepower isn't the most important aspect of this. It is torque. You probably want to avoid a transmission and use a single stage reduction with a belt or chain drive. Matching the final drive ratio with the tire diameter and anticipated performance. Horse power will ultimately determine only the top speed.

You should also look at the AC-20 and AC-23 graphs.


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## frodus (Apr 12, 2008)

I think the top speed of 65 is a little low. You don't want the torque to fall off and have an absolute max of 65, you need some headroom to accelerate at 65mph to get out of the way/pass/re-accelerate after slowing down. If you look at the torque curve, as RPMs increase, torque falls off after a certain point. You don't want to be in a low power part of the curve and be unable to accelerate. 

HPEVS is the manufacturer, so trust their numbers and curves. DO NOT 100% trust distributor websites (unless they jive with HPEVS). I think they either have old/outdated information, or incorrectly list the HP numbers. This has always been a problem with vendors not updating their info, even when asked.

Also look at the EVD35 motor. Liquid cooled, tunable controller, display:
http://www.evdrive.com/products/evd-motor-controller/

You could also use a Motenergy motor, and it may give you the top speed you want, and the power. They have brushed motors available and Alltrax makes a good 72V motor controller.
http://motenergy.com/brdcmo.html


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## mrmeseeks (Jun 14, 2014)

I have found the power graphs on HPEVs site, my problem with pinning the HP values down is that HPEVs graphs are not consistent with themselves (the continuous graphs that is, the peak graphs appear to be fine).

Also for the top speed of 65 it is quite unlikely I will actual need to go this speed as I only have 3 km (just under 2 miles) of actual highway (the rest is in city highway where it is pretty uncommon to get above 50) and in my car the only time I get anywhere near 65 is if there is almost no traffic anyways.

And thanks Frodus I'll check those out.


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## frodus (Apr 12, 2008)

Good, as long as you're aware of the limitations of the motor torque curve, you should be fine.

I PM'd you about motors.


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