[ausev] VW FOX CONVERSION, GEAR RATIO QUESTION
loopcat at yahoo.com
Sun Jun 8 17:59:07 GMT 2008
After my 1st failed attemped at converting a '91 Nissan NX (motor too big for car) We had to make a decision, keep the motor or keep the car. So we decided on another donor car, a 1993 vw fox.
Putting the cart before the horse, last year I purchased a rather large GE DC motor. The demensions/weight are very similar to the famed Warp-11. The motor tag states 16hp at 70v, 214amps, 1822rpm, ~210lbs. From what I have heard, The motor was designed for an air-craft-tug. So it should have a ton of torque. By most accounts the motor will function well in an EV.
The major reason for buying the vw fox was that the engine is latitudinally mounted so my GE-11" motor will fit into the car.
After buying the fox, I did a bit of research and found some interesting facts on the transmission. The gear ratios are very low numerically speaking. 1st-3.450, 2nd-1.790, 3rd-1.130, 4th-0.830 R+P-4.110. So I was curious how this would perform with the motor. So I went to Uve's EV Calculator and added these transmission ratios to a vw rabbitt, zilla lv, and trojan t-105. The closest motor on the list was a Kostov. I then lowered the volts (120 t-105) and the motor rpm's (3600) The results are interesting, the motor rpm's were low, but the speed/distance was very repectable, 1st gear was the best with a range of 30 miles between 40-60mph. Top speed ~70mph. At first, I thought the ratio info was bad. Most of the cars on the list have a 2nd gear ratio of about 8.0. But then I saw that the Fiat Palio also had lower gear ratios. So for kicks-and grins, I lowered the volts to 96v. In 2nd gear the rpm's were below 1700 at 50-60mph.
And this leads me to my question. I have sometimes heard that these old GE-11" spin too slow at lower volts, "tons of torque, but no top-end speed". But if the transmission has lower gear ratios then it should produce the mph's, right? Any insights would be appeciated.
Thanks, John Stuart in San Antonio tx..
More information about the AusEV