This is a real quick and dirty formula for figuring carburetor CFM
requirements for a street engine. This "Ballpark" method
is very useful at the swap meet,
parts store, or when impressing friends and family.
Take the engine displacement and multiply by 2. Then
subtract 15% from the total. For a little healthier engine,
subtract only 5%.
This a real ball park formula. For a more accurate calculation,
see the Carburetor Sizing
Calculator. But, this is still a good formula for general
d = Displacement
in Cubic Inches.
(d x 2) - 15% = CFM
EXAMPLE: d = 350 (350 X 2) = 700
(700 - 15%) = 595 CFM