New Open Megaphones

AS you say difficult to judge but 615hp on mufflers? That ain't shabby at all. Assuming 180 degree header arrangement on megs, I am not sure that, say 6,000 rpm these motors would sound that different. What I am trying to pin down is whether sound is dictated by swept or stroked volume and cam choice rather than pure CC's. I guess my engine guru hero JacMac should chime in now as he will know.

And I'll bet he will be watching this as I write.

If I was in the game now, I would definitely have Jac build me an engine and insist he flew over to adjust the tappets between rounds!!
Yes, watching, but will have to write the reply out in longhand first, as if I try to wing it at my typin speed the PC will time out on me...later:), kinda glad were both past it Keith, I hate flying over large areas of water!
With regard to Keiths posts # 7 & 10.
Difference between original FE 427 versus 427 Windsor by Roush or others.
Major differences:
1. rod ratio~ 1.72/1 on the 427 FE & in the region of 1.51 to 1.55/1 on the Windsor versions ( there are many bore/stroke/rod lengths available for these).
2. Cam Timing particularly duration & overlap, Ford race cams from the 1960's had ~318°or more duration & around 80°+ overlap & on wide lobe centers in the 112/114° region.Not too many sensible cams running much more than 290° duration , 75° overlap and tending toward tighter lobe centers of 110/112° on the current windsor based strokers.

Lot of other differences like port size, component weights etc, but the rod ratio & cam timing alter the piston position in the bore relative to valve opening events.
Thats keeping it as simple as I dare .