Compression & leak down numbers
06-11-2005, 07:29 PM
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Compression & leak down numbers
I was wondering if anyone can answer a question for me. I did a compression test on my 993 Cup car today, the results are as follows.
1)178 psi
2)183 psi
3)183 psi
4)180 psi
5)180 psi
6)190 psi
Does anyone know if these are good numbers?
I than did a leak down, again here are the results
1)12%
2)12%
3)12%
4)12%
5)12%
6)18%
My question is what do you make of the compression numbers, leak down numbers and why is the cyl (6) the one with the best compression have the largest percentage of leak down?
1)178 psi
2)183 psi
3)183 psi
4)180 psi
5)180 psi
6)190 psi
Does anyone know if these are good numbers?
I than did a leak down, again here are the results
1)12%
2)12%
3)12%
4)12%
5)12%
6)18%
My question is what do you make of the compression numbers, leak down numbers and why is the cyl (6) the one with the best compression have the largest percentage of leak down?
06-11-2005, 08:58 PM
#2
RL Technical Advisor
Russ:
Those are OK,.....
Your leakdowns are not wonderful though, and that #6 concerns me.
When that was being done, did the person performing the test take notes about WHERE the leakage came from? After all, without that, these kinds of tests are somewhat worthless without quantification.
Those are OK,.....
Your leakdowns are not wonderful though, and that #6 concerns me.
When that was being done, did the person performing the test take notes about WHERE the leakage came from? After all, without that, these kinds of tests are somewhat worthless without quantification.
06-12-2005, 12:20 AM
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Don't know if it matters but the engine was stone cold. It seems to run fine. I check it because at the Glen race the other 993 Cup could pull me. I don't think were the leak could be was checked.
06-12-2005, 12:23 AM
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Engine should be warm for these tests. Compression numbers may increase from your cold numbers. Maybe the same for leakdown?
06-12-2005, 12:44 AM
#5
RL Technical Advisor
Originally Posted by russ930
Don't know if it matters but the engine was stone cold. It seems to run fine. I check it because at the Glen race the other 993 Cup could pull me. I don't think were the leak could be was checked.
The leakage can very easily be detected when the test is performed; after all, thats the entire idea,....
When each cylinder is pressurized and the results noted on the guage, one listens at the air cleaner for leaking intake valves, the exhaust pipes for leaking exhaust valves, and the oil filler tube for leaking rings. This should be SOP for ANY leakdown tests: street or race cars.
