An example of what I was saying would be a 440 makeing 500 hp and 600Lbs TQ you could run it with 3.23 gears and have almost 2000 Lbs TQ at the rear axle(in direct gear for simplicity sake). On the other hand if you had a 302 ferd that made 500 hp you could go just as fast in an other wise equal car but you would only have 411 lbs tq (asumeing same tq per cube) in that motor so you would have to run a 4.86 gear to put the same amount of TQ to the rear axle in direct gear. It is TQ at the rear wheels that gets the car moveing.