I am thinking about having my AFR 205cc heads milled from 62cc chamber down to 55cc chambers to get my compression from 10.75:1 up to 11.75:1

How much do you think that this will gain me?
How much is this going to hurt the flow #s
I have the G5X3 112LSA cam

 

You'll hurt flow and might have intake allignement issues.
Go 59cc with .040 gasket.

 

In my converstions with AFR the hp gained from the compression increase far outweighs the loss of airflow.

I'm getting a set of AFR 195 Eliminators for my SBC and ask I them that very question.

 

AFRs come 66cc, to get to 55 that is 11 cc
11x .006 = .066 mill, I would say that is intake fitment issues

 

I think u mill .006 for 1 cc. that would be .042. I would watch you p to v. I have a 224 228 +2 on a 110. No problems so far. I hope ypu have 93 gas where u live.

 

.066" from a unmilled head is a lot. Watch that intake..

Mike V

 

I have Mahle pistons with -4cc valve reliefs PTV clearance is not an issue..
Intake alignment is my only concern

 

+1. corrected for my opinion..and spelling haha.

 

Best person to talk to is Tony Mamo @ AFR, if anyone knows for sure, it is him. AFRs have a thicker deck so it might not be an issue, he would know for sure.
Let us know what his advice is.

 

What gasket are you currently running? I have the AFR 205s milled .024 to 62cc, with .040 Cometics, and Tony told me that my SCR should be 11.34-1. I tried to check the SCR and DCR myself with one of the calculators on this site, but the program needed to do so, won't work on my pc due to not having the serial numbers off the package to activate it

 

-4cc pistons
.040 gaskets
62cc chambers

 

Im glad u asked this Q im thinking of the same combo but with difrent heads (same cc) and cam. . let us know what Tony tells u.

 

You don't have to go to 55cc to get 11.75. I'm getting 11.75 from 59 cc, -.007 ptd, .040 gasket. Maybe go with less milling and a slightly thinner gasket to help quench height too.

 

anything new about the Intake alignment ?

 

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The heads need to be angle milled. My LS6 heads were angle milled 0 to .090"
to get the chambers down to 58cc's for 11.6 SCR using GM MLS gaskets.
angle milling eliminates any intake manifold alignment issues. Never had any problems with intake vacuum leaks even when I switched to a FAST 90 set-up. Hope this helps.

Jimbo

 

sure it helps. Let me tell u what im thinking (the combo in mind is to replace my pistons to -4cc (to do with a monstaer cam ) but at the same time i would like to keep the compression high so i dicided to go with 55cc heads and up this thread 99NavyTA opend my eyes on the Intake alignment. im just afraid.

 

I would advise you only mill the head to 57 cc's (about .054 off the deck if they are unmilled).

Based on a negative 4cc piston volume and a piston .008 out of the hole, with an .040 gasket you would be looking at 11.51 to 1......perfect for an aggressive pump gas build.

You may have intake alignment issues (bolt holes wont line up) if you mill more than that and peak flow really starts dropping off in the mid 50's as well (over 10 CFM at .600). I have milled a few heads to 57 cc's and they seemed to still accept a FAST intake although I bet it was tight.

11.5 is a solid number....plenty high to make power, and leaves you a whisper of hiproom in case you get bad gas or its real hot and the engine is more prone to detonate. Once knock retard happens and the computer starts pulling timing the extra compression cost you power, not the other way around.

Just an FYI....

Tony

 

ahaaaa gr8 info thanks tony.

 

Thanks Tony!!