Well I just got off the phone with a guy who works at a machine shop specializing in LS motors (Thanks AJ!). Now to business..

What are the specs on 862 Heads off a 4.8??

Hirdlej told me that the stage 2 5.3 heads will work and that I need a 67cc combustion chamber... now Im told that the 862s have a 57cc chamber (thunder550). So with a 57cc chamber right now Im supposed to make more compression correct? (all info obtained from thread: https://www.performancetrucks.net/fo...lanning&page=2 )

Well Brent (machine shop guy) has kinda kicked me in the *** and opened my eyes a little. I need to do more research. SOMEONE HELP! Please!

 

you need 67cc chambers if you are working for a hi-comp 6.0 (4.000" bore). the LQ4/LQ9 has 72cc chambers with the 317 heads. 67cc is what the AFR 205cc heads have.

you need the 57cc chamber heads to maintain stock compression on a 4.8/5.3

 

ok Im looking for about 10.5:1 compression (or maybe a little more) on a 4.8L...

Brent was telling me a 57cc head would create more compression on my motor? Less is more right?

 

your 4.8/5.3 heads are 62cc from the factory, stage 2 heads 5.3 will be close to 52cc, if you go with edelbrok heads from wcch sponser-------------->

you can mill your heads down .40 and have them ported and valve job.

 

correct.

 

my bad, the 862s have a 61cc cahmber stock so a 57cc chamber would bump up your compression.

might could get them milled when you get the work done, maybe .030" and thats all the bump in compression you will get without swapping pistons.

yes less chamber size is more compression. in your 4.8 you are going to want more velocity in airflow than amount of air flow, you have a fairly large cam now, get some heads that speed up the airflow at lower rpms should help alot.

i have no idea how to figure compression, but on the lsx motors w/ aluminum heads, 11:1 can be run with 93 octane

 

ok that makes sense. I was told go with the Patriot 5.3 stage II which are a 67cc and I was told mine are 57cc????

ok so mine are 62cc and Im needing 52cc's?

now then... are these what Im to be refered to? http://www.proheads.com/Wcch%20200.html

 

the more compression I could get and still run 91 (thats all we have here unless I wanna start parting it with some 110 ) would be cool. I may think about doing pistons a little later

 

yep those would be great

 

if you are doing pistons later i wouldnt mill the heads then