Exhaust and Intake Valve Diameters

[Dinoburner]

A naturally aspirated engine intake depends on a column of air at approximately 14.75 inches PSI rushing in to fill a void created by the piston being pulled down in the cylinder. The exhaust empties into the relative void of the exhaust system while also being pushed out by the piston. A side note: The faster an engine spins the more esoteric cam timing becomes I`ll stop here.