One more quickie post on the same thread...
Doug T (7/2/2010)
Flow testing on a bench will show that a flat roof will flow more but in all instances there needs to be a square to round transition for the header tube some place between the flange of such a port and the tube that will speed up the flow causing an increase pressure. I like very smooooth flow paths with a flow reversion as the only change in cross section until well beyond the exhaust flange. Therefore I make the transition as part of the port itself. So, you're saying two things that are news to me. The first: That a flat roof flows better. Of a D port, with the flat side of the D on the top of the port, or bottom of the port?
Second: That you like to radius the port side into a circular shape to match the circular shape of the exhaust tubing coming out of the flange? (Did I catch that right?)
My intuition about the second point is that might lead to more reversion without having some disparity between the square exhaust ports and the circular exhaust tubing. But, I'm still a total newb!
Heber City, UT (15 mins outside of Park City- basically it's in the mountains)
55 Effie