What's very telling is the ~20CFM OOTB difference from .400 through .600 is going to be worth roughly 40HP more to a combination with enough cam and compression to take advantage of it, that's a VERY SUBSTANTIAL difference.
That's what I liked too. I'm thinking that with very little work these heads would go 280 plus and I mean very little. Bell shape the exhaust port to get some speed and let her breath.
Will you please elaborate on what you mean by this?
I guess this question was pointed towards me about exhaust port air speed? If so the average head porter has a desired ex port shape that we aim for. Most ex ports when on a bench are very loud with turbulence in an unported state. When I took a 2 day "theory' class given by Darrin Morgan (google the name) Very little time 1 1/2 hours out of 17 hours was spent on the ex side. Most of us had flowbenches and access to checking port speed so his short lecture on the exhaust side was to properly size the throat to the proper size of the valve being used, bell-shape the port, make the exit as big as possible (without getting carried away) and DON"T just concentrate on ex flow. He was more worried about "airsppeed" than he was about flow number. He gave us a speed number to aim for on the exhaust side (I'll just say OVER 300fps) and it has paid off for me well in testing. I can't get into a discussion on why he told us to do this but like I said, it works. This is exhaust side only. He gave us a number to stay UNDER on the intake side.
