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The LQ4 & LQ9 are very closely linked, the LQ9 has LS6 based heads with the same combustion chamber volume as the LQ4. The extra compression comes by different pistons. They use identical cam specs. as does even the base motor in the Vett. So we can see the extra hp came from more compression, slightly different heads "same port vollumes" & different programing in the computer.

 

Bear: 01"Pewter"C3 :flag:

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Not quite correct.

 

Hypereutectic flat top pistons on the LQ9, cast dished pistons on the LQ4. Same heads on both motors. If you have an LQ9, look at the casting number - 317. Same as on the LQ4.

 

The stated HP numbers from GM are sort of a game anyway. Look at how they rate the LQ4 on the other platforms. They rate different HP on the Denali vs the trucks, but its the same physical motor. Same thing they did with the Z28 and Camaro SS. Same physical motor, one has a differnt air intake - instant 20 HP ratings.

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I'm not saying GM is perfect in any way as you possibly may have the wrong casting number on them but the LQ9 head part # is 12572035, casting identifiable as 035, the LQ4 head is part # 12562317 which you know is identifiable as 317. I would say the only way to know for sure is to find the whole part # which is located under the valve cover between the push rod holes. By the way I do agree with you about differece in pistons as said the two heads carry the same combustion chamber vollume.

 

Bear: 01:Pewter"C3

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Bear, I hope you aren't getting your info from an article in the March (or Feb) issue of GM High Tech Performance magazine or the book "Chevy LS1/LS6 Performance", both by the same author- Chris Endres. I have some concerns about that source. I have yet to see an 035 head. I've looked on SSs and Escalades and have not seen one. My LQ9 has 317 heads.

 

317.jpg

 

Does anyone here have 035 heads on their SS?

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  • 6 years later...
  • 2 years later...

Not to beat a dead horse but is that the difference between a N code and U code. N code LQ9/345hp U code LQ4 300hp. I triing to pick up a LQ 9 for my LS mustang swap and want to get the right one. Found an 05 caddy LQ9. Thanks.

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Not to beat a dead horse but is that the difference between a N code and U code. N code LQ9/345hp U code LQ4 300hp. I triing to pick up a LQ 9 for my LS mustang swap and want to get the right one. Found an 05 caddy LQ9. Thanks.

this thread is 3yrs old FYI ....but from what I read above the difference is the pistons..... but I no expert on this just glanced thru seems to have same head,cam just different piston Edited by BLNAWAY
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