While the LS1 heads will bolt on the block, they will not work correctly with your LS6 calibrations, cam, and block.
LS6 heads raise the compression to the needed 10.8 to 1, by using a smaller cc chamber.
LS1 heads, by design, may flow more than enough, however, you will not get the peak power that you are looking for, because of the 10.1 to 1 compression ratio that will result from putting the heads on.
Sorry, but just the facts, c4c5:z:hammerdoingengines
The heads have been ported and I am going to replace the cam and reprogram the PCM, would this make them as useful as any LS6 heads? Should I just stay with an exchange for ported LS6 heads for this package? I was trying to keep my stock heads as is and use the LS1 heads I have found. IF it's not going to work for the best though I wouldnt do it.
The LS6 heads 'out of the box' are outstanding. While the LS1 heads are only very good.
The opinions I have seen say that fully ported, both heads are very comparable.
If I were brave enough to void my warranty, I think I'd go with well ported LS1's and save my original LS6s (matching numbers and all that).
As c4c5 states, they would need to be milled to set the correct CR.
Just make sure they were ported by someone who really knew what they were doing, otherwise they may be short of stock LS6 heads. If you unsure, get them flow tested and compare the entire curve to other known good heads.
They are 10.5:1.
(I think...) Another concern you should think about is what year LS1 Heads are they? There may be an issue with them matching up properly to the LS6(all 2001 really) intake manifold. As long as they are form a '01 or '02 LS1 that shouldn't be an issue. The compression ratio on the "worked" heads might not be an issue. whenever "Most" people have there heads done, they take "30" off the deck which will give you an extra 1/2 point compression. Bumping your LS1 heads to 10.6:1. Doing the same thing with LS6 heads you'd be at 11.0:1
DJ Worm, You're no where near needing to worrying about piston-to-valve clearance. Without checking my valve-train geometry, I "think" you can run "almost" .570 "Effective" lift(just in case you've got 1.8's instead of 1.7's) without any probs. But, I may be a little off on my #'s.
10.5 static, 10.8 linear. Sorry, should have been more specific.
As for the milling, good question, as we are told if there is a warp of .006, to replace the head. I do not have milling specs for this engine.
i didnt see any mention of it but are you gonna stay with the stock exhaust manifold? Cause one thing to consider is if their will be any restriction if you do use the stock headers due to their d-shaped ports.
I have found a set of LS1 heads that have been ported and am
wondering if it makes sense that they would work on my Z?