I purchased what is listed as Stage 3 heads from More Performance Inc last year for my 5.3 2K SILVY 4WD. (I won't bore you with how many times I sent them back to have them doen right) Motor was bored 20thousandths, put in JE supercharger (I have Radix SC) pistons and pins, had motor balanced cleaned yadda yadda and so forth. I lost a thrust bearing of all things and well....back to the drawing board. Well I replaced the 5.3 with a 6.0 (2002). The only thing I did to the 6.0 was put rod bolts in.

LOOOOOONG story short...More Performance says I can just swap the heads. Might need to change the push rod size (which I did), but everything will swap fine. I asked what about the chamber, isn't it bored for the 5.3. They said it will be fine. Well, what y'all think?

Head specs: 5.3 LS-1 CC's:60.5 Intake valve: stainless 2.02 and exhaust stainless 1.6 dual springs (crane 144832-16) intake installed height 1.74, exhaust installed height 1.76, intake seat pressure 150, exhaust seat pressure 140, exhaust open pressure 360, AMOUNT CYLINDER HEAD WAS CUT .010, intake and exhaust valve guide clearance .0013, seal to retainer clearance .728, max lift .600

sorry for so much, just want to give you what I can. So what else besides cam specs (224/228 .568/.571 114 +4) would you need to know? I only ask because right now I am fighting the PCM giving me tons of knock retard at throttle. I have a safe tune in and the pcm has been swapped to 2002 as well. sigh. ANY input or suggestions would be greater appreciated.

 

Youre wondering if you can use heads with a 3.9" combustion chamber on a block with a 4" bore? Yes, you can, but you need to use the 6.0L gaskets so it dosnt hang into the cylinder. You will of course have to watch compression now that the combustion chamber on the 5.3L heads is much smaller than one on the bigger bore heads.

 

see, i forgot to mention i did indeed put on 6.0 head gaskets. How would a not so big of a gear head like myself be able to keep track of the compression ratio? The only way I know for sure is to actually measure the volume of the cylinder and chamber at BDC and then divide that by the chamber volume at TDC. I am obviously not in position to do that now...engine is together and running. I guess I could get the chamber volume from More Perfomrance and use an equation to figure it out.

With my current setup I am getting 7.6psi of boost from radix. How would i factor this in?

 

gotta love google.com

compression gauge checks

 

Unfortunately I cant really tell you how to calculate compression off the top of my head. There are a couple calculators around the web though. Yes, call up whoever did your heads and ask them what the CC volume is. Boost does not change compression ratio. If anything, CR affects how much boost you can run. Also, you need to know how thick your gaskets are, rod length, piston crown height and calve relief volume or dish/dome volume, block deck height (if it was cut) in order to calculate compression.

 

thanx! Yeh I knew I had to figure the gasket into everything as well. The 6.0 should have enough info floating around here (web) that I could round up almost all of the specs except for the chamber. Although, if the heads are rated at 60.5cc's then could I just figure that 60.5 divivded by 4 is the chamber cc? 15.125 sounds awful small though.

 

Lets try this in Internal Engine

 

You combustion chamber volume is 60.5cc's, at least that is what it says in your spec sheet. That is what you figure into your calculator. When I plugged it into the calculator I use, I came up with 11.26 :1 static compression. That's not really a good compression for a supercharged motor and is prolly why you are seeing some knock retard. If it were me, I'd either sell the heads and get some ported 6.0's, or remove the blower and put a 150 shot on it. A intercooler, if you don't have one, could also aid in bring down the retard.