Im wanting to benchflow my intake I just worked over, guy asked for stock flow #'s I gave them to him. He then asked how many inches of water the factory rates them at, I dont have a clue. I think heads are rated at 18, or 28?? inches, anyone know what the intakes are flowed at? Im stumped. TIA!

I flow everything at 28"

Thanks. Is it best to attach the intake to a head to get an accurate reading? Wondering what method GM used to get their base/runner cfm readings from. I have a feeling whatever results i get it may not be accurate without being able to duplicate GMs method.
Maybe I should just bolt it on and head back to the dyno to see whats what.

A lot of the flow data you see posted for TPI runners and bases came from two sources; the TPIS Insider Hints Handbook and Ray Bochaz's testing documented in Vette and GM High Tech Performance. Both tests flowed the bases and runners individually and in some combinations. Don't recalling seeing data for the full intake tract from runner entrance to intake valve but that'd be an interesting test.

Well, I found someone who will flow them together and individually. When it gets done Ill report back with the information. Thanks for the tips, guys.