Port & polish 97 heads flow like 99PI's?

[Turbo99GT]

Originally posted by Try Me
If i port and polish and do a valve job on my 97 heads - will they flow like 99's? What kinda gains can i expect?

They should flow a little better, but that isn't saying much. Without the cams and intake, you will definitely not gain 35-60 hp even in a boosted application. The PI heads flow 180-185 cfm on the intake side at .500 lift. I have heard of ported 96-98 heads flowing just over 200 cfm with a good P&P. PI heads P&P could be made to flow over 250 cfm with larger valves. That is a significant difference. Anyway, to answer your question, they should flow as much if not more, but you need other parts to make it all work. SVO/FRPP heads are only rated for 35 hp alone when put on 96-98 GTs and they flow alot more than ported stock 96-98 probably ever will. You might gain 15-20 hp max.