Which heads?
Oh, LOL on the head comment. This is how I see the heads. 273 @ 180 cfm is a higher velocity through a smaller port and valve, the reverse for the 360 head. The difference is tiny and not worth a quibble over. I’d just take the higher volume of air with the larger valve & port and not care a bit about any reduction in velocity at this stage of the game. The higher rpm ceiling and power production would be the win win for me.
I happen to use closed chambered aluminum heads for a just shy of a 11-1 ratio and use pump gas 93.
I’ll have to find the recipe but I think it was around $700. The job I had done wasn’t a simple re-stalling as it is now rated by them to be fine for use up to 650 HP with billet parts. I’d give more info but I’m not remembering it all well right now. It could have been done a lot cheaper of course, but I know the wife and I’m sure it is just a matter of time before I’ll be upgrading that again for more power.
Oh, LOL on the head comment. This is how I see the heads. 273 @ 180 cfm is a higher velocity through a smaller port and valve, the reverse for the 360 head. The difference is tiny and not worth a quibble over. I’d just take the higher volume of air with the larger valve & port and not care a bit about any reduction in velocity at this stage of the game. The higher rpm ceiling and power production would be the win win for me.
Oh yea! That’s the slug I sent with and installed it at zero deck height. You’ll get about 9.8-1 with open chambered heads & a .039 head gasket this way with a really good quench area. But that’s your call.
I happen to use closed chambered aluminum heads for a just shy of a 11-1 ratio and use pump gas 93.