Zero10

Checking the leakdown this weekend. I didn't bring my compressor up the first time.
The compression numbers are a bit wacky...
Front to back, 120, 110, 100, 110
I would expect leakdown in the 15-25% range given what I have seen.

However, all 4 intake ports have BIG spirals of carbon on them, it looks like the intake valves are all leaking, so the head probably has to come off. I'll get some pictures of this up the next time I am working on the car.

It's nice to have my subaru going again, I can haul a compressor around in it, no problem

ehall

I am not going to say anything...
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Lutjen


Well said!

Porsche-O-Phile

Zero10, the factory manual spec for compression (just checked it) is "10 bar positive pressure and above". This would mean 145+ psi so apparently there IS some effect due to compressive heating and corresponding pressure rise inside the cylinder, above what is theoretically possible based solely on volume. Sorry for the bad news but it sounds like either the rings are shot, the valves (as you mention) or both. Or (knock wood) there's some significant cylinder damage. The 110 number you see is a full 25% less than that, so something is badly wrong.

Here's the kicker. . . just for giggles I checked the manual for the n/a and (guess what) SAME spec!!! Right out of the book: "10 bar (145 psi) or more". Someone want to explain THIS one to me??? How can the compression spec be the same for an 8.0:1, 9.5:1, and 10.6:1 ratio engine?

special tool

I only get 125 compression, but the lobes on my Andial cam are about 1/2 inch wide...

Porsche-O-Phile

Andial makes stuff for 944s? Since when?

special tool

They made a full race cam and a sport cam in the early 90's. No longer available.
Mine is 310 degrees from zero to zero

UK952

My special grind cam has got more overlap it goes 380 degrees from zero to zero - not cheap though!
Tony