How can a converted EV maximize efficiency in the transmission?

Question

I have a 1997 mercury tracer (read Ford Escort) with a bad engine, and I'm looking at the idea of converting it to use an electric motor. The motor isn't really the issue, but rather than get a transmission that is specially designed for that type of motor, would it be possible to reprogram the transmission shift values for the existing automatic transmission? Electric motors tend to have higher torque at lower RPM than gasoline motors, and lower torque at higher RPM. I also expect it is likely that the electric motor will be able to safely run at much higher RPM than a gasoline motor. For the sake of efficiency, I want to change the transmission shift patterns to accomodate the different torque values.

Answer 1

Electric motors do have higher torques at lower RPM, which is why they don't need transmissions.  This is because an electric motor effectively has a fixed power output, P ∝ v*Τ.  

A gasoline engine needs a transmission because it reaches maximum power at around 3000 RPM, and definitely must be above 1,000 RPM to even operate.

At 60 mph, your wheels will only turn at about 2800 RPM, which is well within the ability of an electric motor.

Most EV conversions either remove the transmission (it's a good 100 lbs of extra weight), or (in the case of transmissions which include a differential) fix the transmission to the highest gear.  The Tracer is front-wheel drive, so it's transmission probably includes the differential.

There are actually benefits to having a transmission with an electric motor, but an automatic transmission is tricky.  It may even require that the motor be kept turning even when the car is stopped.  You should either see if you can make the clutch bands operate manually, or replace the transmission with a manual.  

BTW, automatic transmissions usually determine when to shift by pressure gradients which act mechanically on the transmission's parts, not via an external computer.