PennyWise

I had a PPI done by our Porsche centre a 92 968 with 112 500 miles.

These are the numbers: (Sea Level) Any comments are welcome.. based on these, I need to make decision to buy or not. Thanks

Compression Test - dry
Cold
Cyl1 1300 kpa - 188.5 psi
Cyl2 1325 kpa - 192.1 psi
Cyl3 1275 kpa - 184.9 psi
Cyl4 1275 kpa - 184.9 psi

Hot
Cyl1 1275 kpa - 184.9 psi
Cyl2 1300 kpa - 188.5 psi
Cyl3 1250 kpa - 181.2 psi
Cyl4 1250 kpa - 181.2 psi


Compression Test - Wet
Hot
Cyl1 1400 kpa - 203 psi
Cyl2 1400 kpa - 203 psi
Cyl3 1450 kpa - 210 psi
Cyl4 1400 kpa - 203 psi


Leakage Test - Dry
Cold
Cyl1 20%
Cyl2 16%
Cyl3 24%
Cyl4 22%

Hot
Cyl1 12%
Cyl2 14%
Cyl3 18%
Cyl4 19%

Leakage Test - Wet
Hot
Cyl1 12%
Cyl2 10%
Cyl3 12%
Cyl4 14%

Spidey944

LEakdown numbers seem a bit high. Did they mention where they were leaking from? Crankcase, exhaust or intake? Did they even pay attention or just get the #'s?

PennyWise

I feel the same way about the leakage numbers... the last time I had 10%-12% I had a scored cylinder wall. I asked for the location of the leakage but have not yet spoken to the workshop.

Remotecontroller

[Folks,

I am trying to find out what these numbers should be for a stock or "new" 968 motor (mainly compression) - can anyone tell me? My mechanic tested my 968 and said it was at 230 on all cylinders and that just seemed really high to me (94 968).

Thanks in advance!![/I]

dontnow

Sounds like it is a little tired. When the compression numbers go up and leakage down when wet usually is rings/cylinder walls. If it is valve seats, usually the oil will not change much.

Also did you watch? Was the throttle held open during cranking?

Remotecontroller

The numbers above aren't for my 968 - just one of the results I found when I was doing a search on prior posts. Do you know what "stock" compression and leakdown values should be for a 968? The only thing I know so far is that my compression in each cylinder was at 225 - 230 with the throttle held open while cranking.

Thanks!!

MAGK944

I use the formula cr*14.7=psi for a rough estimate. "cr" is the compression ratio of the engine. Too many variables really to give one definitive answer, hot, cold, wet, dry, advance, age/wear, etc.

More important are that all the cylinders read close to each other and don't change much wet or dry.

My formula for the 968 comes out at:
11*14.7= 161.7psi
So anything above that is ok.

Fara

I'm not sure if anyone else has noticed, but this thread is from 2008.

dontnow

Nope, didn't even look.

Remotecontroller

I know it is an old post - just trying to give numbers from one of the posts that came up when I searched for 968 compression #s. Sorry if you are not supposed to do that. I did look but can't find anything giving factory Compression and leak down #s.

as far as the formula from Magk944 - it shows 161 but I have 230 +/- 5 PSI and that seems high to me. The Variocam motors were higher compression that many, but that just seems high (and it is a high-mileage motor).