SBM Edelbrock/Speedmaster Head Data

Earlie A said
I think I follow the logic. Not pretending I'm right either. It's my understanding that cid, rpm and # of cylinders determine cfm demand

Cid x rpm / 3456 = cfm x VE% = actual cfm (displacement over time)

Eg.

318 @ 6113 rpm 90% ve = 506 cfm
360 @ 5400 rpm 90% ve = 506 cfm
440 @ 4418 rpm 90% ve = 506 cfm

Earlie A said
and therefore the ideal valve size. The valve size (somewhat) fixes the throat size. Since cfm is already determined, this fixes the ideal port size because of target port velocities. There are equations for all of this.

Ideal for a highly competitive racing series or Joe Blows average street strip car/weekend burnout machine? I think to many worry about the 1st but are building the 2nd.

Here's some video's and a channel you might like.

Earlie A said
The real world of bore sizes, combustion chamber shapes, head bolts, water jackets, pushrod locations, hood clearance height and on an on force the valve and port sizes and configurations to be less than ideal, especially in a older street motor.

Some of the newer HiPo stuff and any good race motor - the whole intake system is totally interdependent.

Agree