How do you choose an EV motor which will deliver high horse power and torque equivalent to a gas powered sports car?
In an EV, the motor is basically the middleman between the batteries and the road. So the question is, "which motor can deliver the torque I'm looking for without destroying itself in the process?"
The motor that will fit your needs best depends on how heavy the car is and whether you're looking for quick acceleration or flat-out speed.
You're looking for the smallest motor possible that can accomplish this, because the extra weight of a larger motor would be better spent on batteries. Aggressive cooling of the motor and controller helps, too.
For quick acceleration, you really can't beat the series wound DC motor! A light-ish to medium size car will use a 9" motor, a heavy-ish car 11".
I would definitely recommend talking to a conversion shop or motor distributor about your specific needs before you actually lay out money and buy a motor.