Aftermarket/Replacement Cylinder Head Rule Change

Dwight Southerland · 04-12-2018, 06:44 AM

Bill Jenkins always said 10-12 HP. Chevrolet engineers said it helps more with higher compression ratio and dome in the combustion chamber, but that it was about 10 hp on flat top pistons (350 cu in, 10.5 compression). I have only seen an un-scientific test once on a 377 dirt track engine when a pair of ported 461 heads were replaced with unported 292 heads and the difference was 22 hp.
If high compression benefits more, then consider that all blueprinted 62-70 327 and 350 flattop pistons engines run between 11.5 to 12.0 compression.

04-12-2018, 06:44 AM	#11
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,002 Likes: 64 Liked 783 Times in 195 Posts	Re: Aftermarket/Replacement Cylinder Head Rule Change Bill Jenkins always said 10-12 HP. Chevrolet engineers said it helps more with higher compression ratio and dome in the combustion chamber, but that it was about 10 hp on flat top pistons (350 cu in, 10.5 compression). I have only seen an un-scientific test once on a 377 dirt track engine when a pair of ported 461 heads were replaced with unported 292 heads and the difference was 22 hp. If high compression benefits more, then consider that all blueprinted 62-70 327 and 350 flattop pistons engines run between 11.5 to 12.0 compression. __________________