Compression Test

[billy mild]

I did a compression test today. It was done on a warm engine, not hot. Meaning I drove the car for 15 minutes. Then let it sit for about 1.5 hours. I then measured the compression.

Here are the reading: 120,125,125,120

I thought that was within range and good. The car doesn't burn oil or anything.

[wild man]

Ideal is like 145, but those numbers are within the acceptable range.

[Arizona_928]

my turbo is identical. Mine has 200k+ miles now though. =p
have you done a leak down test?

[944hal]

I just put a new engine in my 951. Compression was 150 PSI on all cylinders with a 2% leakdown. The head was rebuilt about 5K miles ago. I have no idea when the rings were replaced on the block I bought but the bores were smooth and the leakdown indicated the rings were OK. I think your numbers may be a little low. A leakdown test will give you additional information.

[Pete R]

Another good thing is that they are relatively the same. They are wearing even, there has been nothing odd or catastrophic to one cylinder.

[wild man]

Originally Posted by 944hal

Compression was 150 PSI on all cylinders

The manual states that anything over 10bar is TOO high. If the head was redone, it may have been shaved to correct for some warpage. In that case, you are supposed to use the extra-thick head gasket, which probably wasn't done. Other than having a higher potential for knocking, I don't think you will have any problems though.

[944hal]

The head was shaved to true it up, so yes, that is probably increasing the compression. I'm using a wide fire head gasket and mix 100 octane when I track the car.