Im trying to calculate the air flow of my vehicle at various RPM so that I can take efficiency measurements from compressor maps. I figure someone on here has done this before and can confirm that I am doing this correctly. I am using this formula.

cfm = (cid)(rpm)(0.5)(Ev)(Pr)/1728

cid = My engine is an H22, which is 132 cid.
rpm = Lets say I calculate for 7000 rpm.
Ev = I am assuming my engine will be about .85, which from what I can tell is the baseline value used.
Pr = Pressure Ratio. I am calculating for 7 psi, so
(14.7 + 7)/14.7 = 1.476 bar

This gives me air flow of 335.43 ft^3/min.

The compressor maps that I am reading use air flow in lb/min, so I found online that air at sea level is .07657 lb/ft^3.

So my H22 at 7 psi is flowing 25.65 lb/min of air.

Does this sound about right?

 

ttt

 

s e a r c h