Compression Test / LeakDown Test Results.....Opinions?
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Compression Test / LeakDown Test Results.....Opinions? Hey Guys, I have just been having some bad pinging when I spray nitrous and my motor just kinda feels weak with the heads/cam setup so I did a compression check and a leakdown test and wanted opinions.
Cranking Compression:
Cylinder-PSI
1-210
2-210
3-210
4-210
5-210
6-180
7-210
8-185
Leak Down Results:
Cylinder-% Leakage
1-14%
2-13%
3-14%
4-11%
5-17%
6-12%
7-18% Air coming out of air filter
8-13%
Cranking Compression:
Cylinder-PSI
1-210
2-210
3-210
4-210
5-210
6-180
7-210
8-185
Leak Down Results:
Cylinder-% Leakage
1-14%
2-13%
3-14%
4-11%
5-17%
6-12%
7-18% Air coming out of air filter
8-13%
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The only really noticable sound I noted coming out of the air filter. I was told I need to do that cylinder again with the PCV tube disconnected because when it is still hooked up, even a bad ring would leak through the PCV system and out the intake.
Considering the only variation was on #6 and #8 and they are next to each other, you could have hurt the head gasket between the cyl. BUt those cyl had the least leakage
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From: Was New Orleans, but swam to Baton Rouge
I just responded again to your post on the vette forum. You are right with watching the leak down numbers. The compression test really just tells you there is a problem. The leak down can tell you where the problem is at valves, rings, headgasket.
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From: Was New Orleans, but swam to Baton Rouge
The numbers I go by are 10% or less for NA applications and normally a little higher then that for supercharged or nitrous built engines. I would say anywhere from 10% to 18% for FI and juiced stuff. Anything over 20% or around 20% would be an issue. I recently had mine leaked down and most cylinders were 5% and 8%.
Hello as well.
Hello as well.
IMO, less than 20% on an engine that has been run thousands of miles with H/C/N2O is not too shabby. Was the engine warm or cold at the time of the tests? Did you try a little oil in the cylinders to see if the results were an improvement?
If you ran it cold, its possible that you could see better numbers re-running the test.
If you ran it cold, its possible that you could see better numbers re-running the test.
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From: Shreveport, Louisiana
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93 octane fuel. Never pinged before I installed heads. When I got it looked over by LG the KR was 0 in all places except one little spot where it was .3
Might be tough to tell if you aren't keeping a log of weather conditions each outing, but MPH could point to a loss of power (from one of your earlier posts). Has your MPH fallen off at the track?
Since you are running 93 octane, is it only pinging on the spray?
Is is possible you have a mis-matched combo of fuel & N20 jets leaving you too lean?
How many total miles on the short block?
On the top end since you installed the heads?
Did you have to notch the pistons for PTV clearance?
Do you know if the edges of the valve reliefs were smoothed to avoid a hotspot in the chamber?
Sorry for the long list of questions, but I bet that setup runs like a bat outta hell, especially on the spray, and hoping you find the solution.
same question - same time. I'd normally say great minds think alike, but I've spent too much time in the Advanced Eng forum and know I'm more average than great... 
Since you are running 93 octane, is it only pinging on the spray?
Is is possible you have a mis-matched combo of fuel & N20 jets leaving you too lean?
How many total miles on the short block?
On the top end since you installed the heads?
Did you have to notch the pistons for PTV clearance?
Do you know if the edges of the valve reliefs were smoothed to avoid a hotspot in the chamber?
Sorry for the long list of questions, but I bet that setup runs like a bat outta hell, especially on the spray, and hoping you find the solution.
Originally Posted by brad8266
Figured id ask, did you do the test with a hot engine?
Read this in another thread and thought this might be worth asking here as well.
Might or might not, either way - good luck!
Might or might not, either way - good luck!
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Might be tough to tell if you aren't keeping a log of weather conditions each outing, but MPH could point to a loss of power (from one of your earlier posts). Has your MPH fallen off at the track?
Since you are running 93 octane, is it only pinging on the spray?
Is is possible you have a mis-matched combo of fuel & N20 jets leaving you too lean?
How many total miles on the short block?
On the top end since you installed the heads?
Did you have to notch the pistons for PTV clearance?
Do you know if the edges of the valve reliefs were smoothed to avoid a hotspot in the chamber?
Sorry for the long list of questions, but I bet that setup runs like a bat outta hell, especially on the spray, and hoping you find the solution.
same question - same time. I'd normally say great minds think alike, but I've spent too much time in the Advanced Eng forum and know I'm more average than great...
Since you are running 93 octane, is it only pinging on the spray?
Is is possible you have a mis-matched combo of fuel & N20 jets leaving you too lean?
How many total miles on the short block?
On the top end since you installed the heads?
Did you have to notch the pistons for PTV clearance?
Do you know if the edges of the valve reliefs were smoothed to avoid a hotspot in the chamber?
Sorry for the long list of questions, but I bet that setup runs like a bat outta hell, especially on the spray, and hoping you find the solution.
same question - same time. I'd normally say great minds think alike, but I've spent too much time in the Advanced Eng forum and know I'm more average than great...
See, I thought about that and didnt think a dynojet could be loaded but he said he loaded it ?????
I see in your sig that you have afr 205 heads, G5x3, and the bottle. Tell us about your fuel injectors and fuel pump. What is your total advance timing while spraying. From here we can offer better advice. Without this info, anyone that comments is just shooting from the hip at diagnosis......
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I see in your sig that you have afr 205 heads, G5x3, and the bottle. Tell us about your fuel injectors and fuel pump. What is your total advance timing while spraying. From here we can offer better advice. Without this info, anyone that comments is just shooting from the hip at diagnosis......
SVO 30# injectors on stock pump. My first thought before taking it back to LG for them to look over the tune was that I needed a better fuel pump but Sean said the fuel was fine.
21* timing WOT