air flow #s ?

[Alan Roehrich]

The 28" of water pressure drop is the industry standard.

However, recent testing shows that even 28" not really adequate or ideal for state of the art race heads. A few guys who port Stock and Super Stock heads say that applies even more to Stock and Super Stock, given the restricted nature of the rules.

Further, if you know anything about a flow bench, you know it is like a dyno, and comparing results from one flow bench or dyno to results from another flow bench or dyno is nearly pointless. A few years back, several flow bench owners got together and sent a single calibrated orifice around and used it to calibrate all their flow benches. The results were eye opening, to say the least.

A flow bench, or a dyno, is merely a tool, best used for back to back testing to verify work done or parts bought.

To answer the original question, in all honesty, introducing any sort of extra correction factor only adds to the error margin. If you're "correcting" results from one bench, on one set of heads, in order to compare them to results from a different bench on a different set of heads, you're wasting a lot of valuable time.