Forced induction, higher compression...these things may do the job of higher displacement (more oxygen molecules through the engine), but it isnt the same. The density changes, not the volume (cubic inches, liters). And yes, torque is what counts, but horsepower is a function of torque as related to engine RPM. So if you have an engine that generates its most torque at a high RPM, the car must be geared accordingly. The engine must also be capable of turning such speeds, but high RPM capability most certainly means something. Look at Indy. I admit, Im semi biased because I drive a turbo car. However, my first car was a 69 Camaro SS, and I will be the first to admit that if the same technology that is applied to my 2 liter four-banger was applied to 5.7 liters of American muscle, there would be no comparison in power. But anything can be made to go fast with the right amount of money. EDIT: After reading my post, I realized that part of what I wrote is wrong. Higher compression is COMPLETELY different. It does not move more air through the engine. With higher compression the SAME amount of energy (oxygen) is released under HIGHER pressure, producing more work.
