A friend of mine is currently doing a 6.0 swap. One of the header bolts broke and is stuck in the 6.0 heads. As a result, we will be using the 5.3 heads. Here are my questions:

1. How much will the compression ratio rise due to using the 5.3 heads?

2. What heads gaskets will be needed? The ones off the 5.3 or 6.0? The heads have not come off the 6.0 yet and can't compare them.

Any input is much appreciated.

 

i think you have to have the 5.3 heads machined for the bore of the 6.0. I could be wrong though, i'm not up to speed totally on the internals of the lsx. compression wise, i think bumps it up a half point, on a ls1, so maybe not even that much on a 6.0? i think you'll be safe, compression wise.

 

Let me just add.... this is an LQ9 with a CR of 10:1 with stock heads.

 

5.3 heads on an ls1 are 11:1

 

send the 6.0 head to a machine shop and have them drill it out and retap it

 

sounds like a good excuse for some head work

 

1. Compression will jump to ~11.3:1, pushing it on pump gas IMHO. The 5.3L heads have a 61cc combustion chamber which is 10+cc smaller than the 6.0L heads.

2. 6.0L head gaskets will be needed because of the bore size.

You don't need or want to mill the 5.3L heads for the 6.0L bore if you use them.

 

A machine shop might be able to tack weld a bolt onto the broke one and get it out.

 

your gonna loose power if you go this route unless you get head work done to the 5.3l heads. just send the head to a shop and have them easy out the bolt. then reinstall them or have them port and polished while there then put them back on. try search its all over on this site i personally would not put the 5.3 heads on the 6.0. it will crank the compression up but it may be too much for pump gas and they will not flow near as good. IMHO

 

Thanks for the help.. 6.0 heads were used.