The best approach to gauge genuine power is to quantify the time it takes to pump the supply tank of known volume from a known beginning weight to a known completion weight. At that point you can figure the genuine CFM from the distinction in beginning and last weights, times the volume of the tank, isolated when it took to pump up. You can likewise time the pump-up cycle from the slice into the cut-out weight, since that is the means by which one as a rule runs a compressor.