Carburetor cfm calculator

The problem is the way carbs are rated. That rpm x cid / 3456 = cfm formula is that it says your engine moves 550 cfm, the problem basically any carb you put on becomes a 550 cfm carb but at different vacuum level so say a 390 cfm 4 bbl will flow the 550 cfm but at a higher vacuum level aka more restrictive a 950 cfm carb will flow 550 cfm but at a lower vacuum level less restrictive.

You don't need a formula we already know what works, if your trying to get the best power or best power and drive ability etc.. sometimes you got to try a few to dial it right in. But generally 600-650 cfm mild 400-350 hp and under, a 750 cfm 350 + hp but even under 350 hp a 750 cfm can be made to work etc..