Your right, I was thinking that wrong. The writer wrote that more than 15% of bore in lift created turbulence, killing velocity. I don’t know his theory.
That doesn't make any sense so I'd avoid following that theory. Race engines almost always have valve lift that is greater than 15% of the bore size. A 4.50 inch bore would be restricted to 0.680 lift which isn't enough for a big race engine. A big bracket engine will use lift somewhere in the 0.750 to 0.850 while a pro built engine will be up to an inch of lift.
