What should the cylinder compression be on a stock LS1?

I just rebuilt mine, haven't dyno'd or tuned it yet. It has a .581 lift comp cam with LS6 Style Patriot heads. I only checked one cylinder and it was 135 pounds, I think that sounds low? There is about 500 miles on the motor

Thanks

 

That sounds real low. Mine was at least 155psi and I've got a ton of miles on this engine. You really need to check all the cylinders and double check that one because you may have an issue if that one is lower than the rest.

 

Compression test should always be done with leakdown test.
Reason is that you may show low compression but it could be valve/seat related.
A leakdown will let you know where your compression is leaking from and by how much.

 

Thanks guys, appreciate it.

I think we are having some valve seat issues because it is burning oil. I will check a few more cylinders as well

 

Valve seat or seal? Seats will affect compression, but the seals affect oil consumption.

 

Not sure yet until I tear it back down. Since the compression is low and there is oil consumption I assume valve seats? Will the seats let oil through? I am pretty sure it is not rings, it smokes the worst when let sat and started back up (oil leaking into cylinders)

What do you think?

Thanks