Thread: Carburator CFM

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Can someone tell me how to choose how much carb. i need to look to buy for my engine? I'm under the impression that there is a formula to figure CFM...

Well according to my info, take the engine size say 460XMax rpm say5000XVolumetric efficiency divided by 3456= CFM. So460X5000=2300000X.85[most rebuilt engines have about 85% efficiency]=1955000 dividedby 3456=565.68287, or less than 600 CFM. This is only a place to start for some, but it has worked real well for me like it is.

I like Denny's formula....cubic inches times 2.

From Offenhauser.

IMHO, the Offy 360 is one of the best manifolds you can run on a SBC. I ran one on a basically stock 400 SBC in a '62 pickup. The only changes were an earlier double roller timing chain, an old Isky 30/30 cam, a 650 Holley DP and Hedman headers. It made good low end power and peter out until around 6 grand.

Originally posted by Ives Bradley
Well according to my info, take the engine size say 460XMax rpm say5000XVolumetric efficiency divided by 3456= CFM. So460X5000=2300000X.85[most rebuilt engines have about 85% efficiency]=1955000 dividedby 3456=565.68287, or less than 600 CFM. This is only a place to start for some, but it has worked real well for me like it is.

You just made my head hurt.

Originally posted by techinspector1
I like Denny's formula....cubic inches times 2.

That's what I'm talking about...