Some guys will argue that 28" is too slow for a high output high rpm engine, and so they test at 40" and convert back when comparing other heads.
A 318 with a mild cam will "pull" only so hard on the intake port compared to a larger engine.
If you compare the same rpm range, then the larger engine will want more intake port flow and volume but it will only draw so much before going into a port stall where air will just stop flowing because the airspeed exceeded 614fps.
That's the SAE factor for sonic port stall or choke.
There are formulas that help prevent you from going into a sonic choke buy figuring the engine size, rpm and port size/valve size.
Experienced engine builders will know what parts to use together to make the engine do what ever they need it to do however most of the time either money or time restraints prevent that from happening.
So building a larger or higher rpm engine will actually draw more air through the intake port making it flow more, but only if there is no problem with the intake tract or camshaft selection, or exhaust selection, or ignition!
Brian
