compression test LS1 , my results what do u think ??

[ACII]

Hy all

hope u can give me some feedback about my results of the compression test.

cly
1 = 162
2 = 176
3 = 174
4 = 171
5 = 152 / with oil 159
6 = 181
7 = 192
8 = 200

I heard that between the lowest / highest compression shouldn´t be a difference more than 30%...
Cylinder 5 / 8 is just within that rule of thumb..

But i am not really happy with the big difference..

What do u think.... ?? The engine has only around 50.000 mile on it.

THanks
Achim

[boostedc10]

By GM rules the allowable low is 70% of the highest value. This puts your lowest allowable at 140.

How did you do the test, was the engine at operating temp and how many rotations?

[ACII]

The engine was cold , cuz i already removed the engine out of the car...

I did 4 rotations each..

But i just recognized that i have missed to open the throttle wide open.

Will do the test again...with WOT

CU
AChim

Originally Posted by boostedc10

By GM rules the allowable low is 70% of the highest value. This puts your lowest allowable at 140.

How did you do the test, was the engine at operating temp and how many rotations?

[boostedc10]

Ya at operating temp is the best. One thing to pay attention is how fast it comes up on compression. If they all come up pretty quick (say first or second rotation) I wouldn't worry too much about it.

Cold tests can sometimes be all over the place. If you are really concerned I would do a cylinder leak down test.

[Wasted Income]

I always prefer a leakdown test to a compression test, even though it's more work. Cranking compression test has too many variables that affect the numbers.

Plus, with a leakdown you can "easily" pinpoint where your compression is leaking to.