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Message: <blockquote data-quote="OLD H2S" data-source="post: 1459293" data-attributes="member: 20979">I am pushing the numbers around on the BSFC from .45 to .50 and I am at the limit for 19 pounders, the numbers are coming in at 19-21 depending and I have 24 pounders in the engine right now.I posted the NPI engine above to show how good the heads are..The porting job on that set were not that good and too big and the numbers look good for all the hate they get.  The secret is to barley touch them and keep the port velosity as high as possible for the small piston size of the 4.6 and 5.4 The long runner PI intake helps the stuffing.My max ported PI heads are 180cc ports and that is a lot of cutting and polishing to get there with sets of heads to learn on and destroyed engines as they fail. I think my port velocity is too low with this head.I might try a smaller 70mm TB and see....</blockquote>