CFM formula

[bogger333333]

http://i91.photobucket.com/albums/k291/bogger333333/CFM_formula1.jpg

[Gutter Runner]

This is the formula if you want to figure the correct volumetric efficiency. Most carburated vehicles will run around .85. Fuel injected can be closer to 100%.

CFM=CIDxRPM/1728/2xVE

So using the motor and rpm listed above,

400x5500/1728/2x.85= 541 CFM

[SSrb(2)481]

Fuel injection would have no effect on an engine's volumetric effeciency. The things that would effect the VE are heads, camshaft, intake, exhaust, and carburetor (throttle body). It's basicly a measure of flow restriction and port velocity. My carbureted 481 had a VE of 114% at 7100rpm. Stock engines are usually just more flow restricted.

[Gutter Runner]

Fuel injection would have no effect on an engine's volumetric effeciency. The things that would effect the VE are heads, camshaft, intake, exhaust, and carburetor (throttle body). It's basicly a measure of flow restriction and port velocity. My carbureted 481 had a VE of 114% at 7100rpm. Stock engines are usually just more flow restricted.

Interesting.
How do you find your rigs exact VE? It would be nice to know instead of guessing.

[SSrb(2)481]

An engine dyno will tell you that. It measures the volume of air going in per minute and divides it by (displacement x rpm/2). This could also be found using a standard MAF (mass airflow sensor), and some complex circuitry or an understanding of the output signal. The old TPI's had a MAF that gave an output that was directly proportional to the grams/second flow rate. So if you know the density of air, accounting for temp, humidity, and barometric pressure, you can calculate the volume. This would not be easy, but it is possible.