C5kid

:

OBSSSD

My last LS3 car tested 19X in all cylinders cold and dry with about 3,000 miles on a stock motor. I don't know if the LS9 would test that much lower or not because of the 9:1 CR. It would seem remarkable if your rings are worn because the range between cylinders is fairly consistent.

Maybe someone could measure a stock LS9 and post the numbers up for you?

racerns

I don't know what the cold specs are for a LS9 but those numbers sound resonable for a cold 9:1 compression motor with forged pistons. You would have a little more cold clearance with forged pistons for expansion. That would also explain the gain from the oil.

timmyZ06

A healthy 2JZ had the same exact numbers paterns! Im pretty those numbers are right FI engine will never see close to 2** psi unless modded ! Just cross your data with gm specs!!!

narush

I found out mine are in the same range as yours are currently COLD.

C5kid

C5kid

Having a tough time finding any GM data specs.

narush

When I was doing research for the same information I could not find any data, had to call a dealer and ask the technician.

gonabite

Yes, normal for this motor. I found around the same with my car.

PRE-Z06

I don't know the specs, but the motor having lower static compression and a later ivc point than an ls3 is going to make the cranking psi a lot less.

mirage2991

do a leak down test to really know, compression tests have so many variations such as cam timing, static cr, how fast the starter is spinning the engine, wot or not (without having the engine running of course). It is really only good for a quick check if you suspect a blown gasket or ring, best if you know what it should be, say if you had done it when brand new.

timmyZ06

I agree, leak down test tells much more than a compression test. But if everything shows good, it should be fine, no major problem.