What's with flow bench number shenanigans?

[375instroke]

Aren't these things super easy to calibrate?  I would think an orifice of a certain size would flow a certain amount of air at a certain pressure differential.  Why is this hard to do, or do people just like to lie about their porting skills or products?

[Challenger340]

Aren't these things super easy to calibrate?  I would think an orifice of a certain size would flow a certain amount of air at a certain pressure differential.  Why is this hard to do, or do people just like to lie about their porting skills or products?

As long as the Flow Bench is sold/provided with what's called a "Calibration Plate".... then yes, it's easy peazey to calibrate according to the Plate provided.

Our SuperFlow SF750 Bench came with one...... and we obtain very repeatable/close numbers to many Head Manu's, ie: BRODIX, Trick Flow..... others, well.... not so much ?

Can't for the life of me repeat any edelbrock numbers...... but it doesn't matter much anyways as we only use our Bench as a "Tool" to see if we're going in the right direction and prove before & after results.