Bank 1,
1: 180 psi
3: 190 psi
5: 190 psi
7: 165 psi

Bank 2,
2: 180 psi
4: 160 psi
6: 160 psi
8: 170 psi

I was going to do leak down test on 4,6, & 7 but the air compressor broke. What do you think?

 

"acceptable" is usually 10% variance betwen cylinders. You are just above that.

 

looks like you got a prob. on the cylinders in bank 2 and the last one in bank 1
if i were you do a leak down test and take it from there. might have to pull the motor out

 

How i can test my compression ?

 

You need a compresion tester (Gauge). Take out the sparkplug of the cylinder you are going to test screw the gauge into that cylinder.Disconect your coil packs so it will not start and then turn the motor over six revolutions you will count the revolutions by the needle jumping each revolution and that wil give you a presure reading I think that the LS1 is supposed to be beteen 180-200 about 99% on that and you also don't want a big variance no more than the 10% the other guy posted about. Good luck!

 

I was going to do leak down untill the air compressor gave out. But here is the interesting part, according to GM manual, as long as the lowest compression is within 70% of my highest, I am ok.
I am thinking that since I am running cam/heads, I want my compression to be at most only 10% in variance instead of factory recommended 30%. What are your thought on this?

 

Comp. test is nonsesnse..
U need to leak it down.....

 

When you put a larger cam that has more duration it tends to blead off a little more compression, or should I say, it might not make as much as stock. If you have incressed your compression ratio, then that should yeild a higher compression reading. But if you have both higher compression then stock and a bigger cam, the reading might be close to stock. The thing you are looking for is all the cylinders reading within 10% of each other. Also remember if the engine is hot and just got finished running the readings will be higher then if it was cold and had not ran for some time. I would take some oil and put it in the holes that are low (not too much) and pull another reading on them. If the readings go up then the rings are not sealing as well as the others. If they stay the same, then your valves are lealing. I like to pul a hot test, then let it cool and pull a cold test. Compression readings on modifide engines are only going to tell you how much ware the engine holes have if you pulled a set of reading when it was first new. The new cold and hot readings is what you would then referance back to, not the oem manual. Now if you did not pull referance reading when it was new, compression is still one of the best trouble shooting tools a profesional technitian can use. I work offshore on Large Industrial engine that pull 3200 horspower at 1000 rpm for 24 hours, 7 days a week, 365 days a year. They make the company millions of dollars, and as a profesional technition, if I thought compression was a joke I would be on welfare. It is a very good troubleshooting tool if you know what you are doing. As for your readings, they are not all that bad but I would pull the readings again the way I described. 190 would probly be the reading that all your holes should acheive with your combo. So I would say your engine is getting close to needing to be freshend up. One last thing, while pulling the readings you should hold the throttle wide open. An engine can not build compression if nothing is alowed to enter it. When you pulled them did you leave the throttle closed on all of them? Or could the person turning the engine over have been playing with the throttle? Same strokes for each cylender to.

 

Funny Signature

Joe.