Quote:

What controls velocity?

Piston speed and port/runner shape. In essence, the geometric profile (tube) in which the air travels to the base of the valve head. This geometric shape starts at the top of the intake manifold (carb plate) and some may include the shape of the venturi's w/in the carb/throttle body.



This is the response I see most often on the internet.

How about valve events and ramp rates?