Just did a compression test...
- Thread starter AaronG
- Start date
Car Nut
Founding Member
Your lowest number is only 120 and all numbers are very near each other, so I think anyone will say you're in good shape.
What I can't remember off hand is how low is too low. I think that your numbers are fine, especially for the number of miles.
Did you do the test yourself?
I've got to do this on mine soon just to know what I'm dealing with. I've got a horsepower bug that has just about rendered me terminal, so that's got to be taken care of quickly.
Others will confirm for sure in no time.
What I can't remember off hand is how low is too low. I think that your numbers are fine, especially for the number of miles.
Did you do the test yourself?
I've got to do this on mine soon just to know what I'm dealing with. I've got a horsepower bug that has just about rendered me terminal, so that's got to be taken care of quickly.
Others will confirm for sure in no time.
Yeah, I did the test myself... I did it dry, on a cold engine... But, my numbers seem fine to me. I just went and picked up the gauge at Autozone for 20 bucks, it's not too bad, the only cylinder that was a PITA was #4... all that EGR bull**** was in the way and on of the runners on my headers made it difficult to thread that hose into the spark plug hole... It took about an hour.
Though not as important on a hypereutectic motor, the test should be done on a hot motor (when the motor is cold, tolerances can be off due to differing coefficients of expansion).
As Car Nut said, what matters is the relativity of the values; there are too many variables in methods to infer a whole lot else.
If you want to know more, doing it on a hot motor (all plugs pulled, ignition and fuel system disabled, throttle wide open and a charger on the battery) is more of the standard method. After doing the dry test, do a wet one.
A leakdown test is further revealing.
They look good to me though.
Good luck.
As Car Nut said, what matters is the relativity of the values; there are too many variables in methods to infer a whole lot else.
If you want to know more, doing it on a hot motor (all plugs pulled, ignition and fuel system disabled, throttle wide open and a charger on the battery) is more of the standard method. After doing the dry test, do a wet one.
A leakdown test is further revealing.
They look good to me though.
Good luck.
As Hissin said, they look good to me. When I tested my car, they were all 125-130psi per cylinder. The engine was warm, but I didn't have the TB wide open or all of the plugs pulled.
BlackVert
15 Year Member
BlackVert
15 Year Member
Joe 5.0
Founding Member
Mines 8.5:1, and all were 150psi. I had the throttle open and all the plugs out. Why did you not open the throttle or leave the plugs out? Thats what my tester said to do, and its pretty standard? My engine was cold though also.
I just didn't read the instructions until afterward...
I thought the way I was doing it was correct... There seems to be a lot of wishy washy opinions as to what the correct method for doing it is though... If you do a search (which I did), you come across people doing it like I did, like you did, doing it wet, dry... hot, cold... And getting all kinds of different readings. I wouldn't think a stock 5.0 would be showing much more than 130 psi. Am I wrong?
gcomfx.com
Founding Member
I did mine your way a year and a half ago. My AVERAGE was 118 they were all within 5. I continued to spray it during that time. And ran the numbers in my signature this past fall. It finally stopped producing power off the bottle this past winter. Still started and ran okay.... just no power getting to the ground.
I just pulled the engine last night, hopefully have pics of how the pistons look this coming week. But I would say your numbers are pretty good.
I just pulled the engine last night, hopefully have pics of how the pistons look this coming week. But I would say your numbers are pretty good.
I did mine your way a year and a half ago. My AVERAGE was 118 they were all within 5. I continued to spray it during that time. And ran the numbers in my signature this past fall. It finally stopped producing power off the bottle this past winter. Still started and ran okay.... just no power getting to the ground.
I just pulled the engine last night, hopefully have pics of how the pistons look this coming week. But I would say your numbers are pretty good.
Interesting. 12.79 @ 107.14 -- nice run. With that said, I'm not concerned really... I am just planning on spraying it until it goes and do something along the lines of a 347 when the time allows. As I mentioned earlier, I'm happy with the overall consistency of the #'s. I'll look for your pictures soon. :SNSign:
Aaron
gcomfx.com
Founding Member
A year ago I trapped 108-109 on the bottle, and 98-99 N/A. She just kept getting weaker. But I'm not complaining. It just about made it to 200,000 miles.
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