Racing flow benches

I had a customer who was doing his own porting on a set of these same kind of heads as the test here.
He had them flowed locally(to him) and was pretty unhappy with the results.
And the results were pretty low numbers......... lower than I would have expected for the description of the work.

I asked if he had the head tested before any work was done, and he had.
From about .400 and up, the “before” numbers were a solid 20+cfm lower than I’d ever seen from that type of head before.

Adding 20cfm to his ported numbers put them in line with what I would have expected to see on my bench.