Re: Exhaust crossover tubes
Air mass, velocity, and volume up to the point of the crossover is what controls combustion chamber evacuation when both valves are open. It's all inertia and fluid dynamics. Pretty complicated stuff. If your crossover is futher, it will pull the air harder, but rob power on the exhaust stroke. Too short, and you'll leave exhaust gas in the combustion chamber during the topout between the exhaust and intake strokes. Velocity stacks work on the same pricipal. The piston rounds off at the bottom of the intake stroke and starts back up, but the intake valve is still open. This is because the inertia of the air in the velocity stack is pushing more air into your cylinder. I hate being a physics geek.