Compression test results, normal numbers?
Burning Brakes
Joined: Feb 2004
Posts: 1,069
Likes: 8
From: Sanford NC
You are correct, I shouldn't have used the term overlap, I should have specified long intake valve opening after BDC. I was just thinking a large overlap cam has a longer durations overall.
For break-in, I was referring to my aftermarket build, I believe it takes more than a couple miles to get full compression, no?
For break-in, I was referring to my aftermarket build, I believe it takes more than a couple miles to get full compression, no?
Team Owner
Joined: Sep 2000
Posts: 25,002
Likes: 2,704
From: Far NW 'burbs of Chicago
St. Jude Donor '13
Burning Brakes
Joined: Feb 2004
Posts: 1,069
Likes: 8
From: Sanford NC
2nd Gear
Joined: Nov 2024
Posts: 2
Likes: 0
Adding to an old thread- this is one of the few places a Google search result shows when trying to find out an acceptable engine cylinder compress range for a C6 corvette engine.
I recently purchased a used 2011 Corvette C6 M6 GS, completely stock, 49K miles that has the LS3 engine with the dry sump oil system. I did not have any maintenance history on the car as it was purchased from a dealership with no prior paperwork ( I would have preferred to buy my C6 directly from a previous owner, but that is another story).
I took it to the local Chevy dealership for a compression test , here were the results. I hope they are useful to someone. I know about the 10% max variance desired between the cylinder that has the max compression and min compression numbers. My variance in the cylinder compression numbers is under 5% so that's good. I still have not been able to easily find what are the factory stock cylinder compression numbers for a C6 LS3 engine, so if anyone has a link or knows that info feel free to reply. Thanks.
One observation I see- it appears the compression drops off from the front of the engine to the rear (towards the windshield) on both sides of the engine (driver side front to back: 1,3,5,7; passenger side front to back: 2,4,6.8). I am going to take a guess, this could indicate a problem with the head , such as a gasket leak towards the rear , on both sides? Or maybe the LS3 engine has known heat or wear characteristics that could explain this. I am new to C6s.
Cylinder number PSI
1 192
2 191
3 190
4 188
5 185
6 186
7 185
8 183
I recently purchased a used 2011 Corvette C6 M6 GS, completely stock, 49K miles that has the LS3 engine with the dry sump oil system. I did not have any maintenance history on the car as it was purchased from a dealership with no prior paperwork ( I would have preferred to buy my C6 directly from a previous owner, but that is another story).
I took it to the local Chevy dealership for a compression test , here were the results. I hope they are useful to someone. I know about the 10% max variance desired between the cylinder that has the max compression and min compression numbers. My variance in the cylinder compression numbers is under 5% so that's good. I still have not been able to easily find what are the factory stock cylinder compression numbers for a C6 LS3 engine, so if anyone has a link or knows that info feel free to reply. Thanks.
One observation I see- it appears the compression drops off from the front of the engine to the rear (towards the windshield) on both sides of the engine (driver side front to back: 1,3,5,7; passenger side front to back: 2,4,6.8). I am going to take a guess, this could indicate a problem with the head , such as a gasket leak towards the rear , on both sides? Or maybe the LS3 engine has known heat or wear characteristics that could explain this. I am new to C6s.
Cylinder number PSI
1 192
2 191
3 190
4 188
5 185
6 186
7 185
8 183
Race Director
Joined: Dec 2005
Posts: 11,286
Likes: 953
From: Carlsbad Ca
LS2 should be around 190ish (dry.) And 220ish (wet.)
LS3 a little higher
LS7 even higher yet.
Most important is that all the cylinders are relatively equal. No single cylinder being "lazy."
