Speedmaster head hypothetical
I've wondered how far to go with port volume and larger pinches. As we have discussed, sometimes enlarging the pinch will hurt the flow. There is also a point of diminishing returns with making a port larger. After the port gets so large (volume wise), additional volume increases yield less and less flow increase. Of course the volume has to be added in the right places to keep the velocity profiles correct and to delay separation. But in general, volume increases early in the porting process yield significantly better flow increases.
As rpm increases, pressure wave tuning is more significant. Darin Morgan references 6500 rpm as a loose transition point between high and low speed engines. Tight pinch points kill pressure wave travel in high speed engines.
Does Santa ever deliver dynos?