> Note that Torque is to acceleration what hp is to top speed...
This is a common misconception. Cars with the same -peak- torque and same gearing / wheel sizes, but with different HP, will NOT accelerate at the same rate. Perfect example: Acura Integra Type R and Integra LS. They both have the same size engine, both make the same peak torque (+/- 5%) but have radically different horsepower (140 vs 195) and acceleration.
An easy way to visualize the relationship between acceleration, torque and HP is to look at a dyno curve and imagine a car accelerating. The acceleration at any instant is a function of the torque at that RPM multiplied by the effective gearing of the car, divided by the weight of the vehicle. You shift when the torque multiplied by gearing of the gear you're shifting INTO is at least as high as the torque multiplied by the gear you're shifting OUT of. This, not coincidentally, is the same RPM where the HP you'll shift into is at least as high as the HP you're shifting out of.
Now: A 400 RWHP Viper makes its 440 ft/lbs of torque low in the RPM range, and the torque begins to fall off by 4,800 RPM. The 420 RWHP T/A will make its 400 ft/lbs peak torque higher in the RPM band, and will hold that torque longer. By choosing a different gear ratio, the T/A will be able to accelerate as quickly as the Viper at the same road speeds by running higher RPMs to compensate for its lower torque; the availability of torque higher in the RPM band allows it to do this. A 420 RWHP, 3300 lb T/A should modestly out-accelerate a 400 RWHP, 3400 lb Viper from a roll; from a standing start, driver skill and the Viper's superior traction and weight distribution would play a large role.
