If it's blow-through, it can be any size that works with the engine N/A - the extra flow comes from the increased density. Roughly RPM × displacement ÷ 3456.
If it's draw-through, it has to be large enough to supply the higher power level. RPM × displacement ÷ 3456, then × by the pressure ratio.
Assuming 14.7 as ambient:
5 psi = (14.7 + 5) ÷ 14.7 = 1.34
10 psi = (14.7 + 10) ÷ 14.7 = 1.68
15 psi = (14.7 + 15) ÷ 14.7 = 2.02
OK. It's a blow through setup.
(4000rpm)(254c.i.)/3456 = 293.98 CFM??
So I think I'll just run the Holley 390cfm four barrel. I've used on on this motor naturally aspirated and it worked great.
Thanks again for all of the help!
I'll post my progress in a few weeks.
