Once again a agree that textbooks are just a guide. If they weren't so, everebody would still be using any 3 setup carb or even a quadrijet that flowed 500 cfm in our 250 Chevy engines and nothing else would work properly no matter what they've done on the rest of it.
I saw in some book once that you need to consider the engine purpose and multiply thus the whole cfm formula for a coefficient of correction.
For exemple for street engine which has 85% of volumetric efficiency:
CFM = ((peak rpm * cid)/3456)*.85
And for a track engine that has 100 to 110% volumetric efficiency:
CFM = ((peak rpm * cid)/3456)*1 or 1.1
So this coefficient modifies the whole history. Isn't it?
How the hell, after modifing an engine, you will know the exact volumetric efficiency percentage? Well, a bench flow maybe. But it gives you percentual values?
And how can an engine has 110% of efficiency? It means a machine with no loses and working above its own capacity. Is it possible?
