Just did a compression test...

AaronG

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Jun 25, 2003

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Mar 14, 2007

#1

• Mar 14, 2007

• #1

#4 129 #8 130
#3 120 #7 130
#2 120 #6 130
#1 128 #5 130

What do you guys think? The car has 139k on it... It's had two previous owners, one of which modified the car, so I dont know exactly what was done to it. But I'm pretty pleased.

 

Car Nut

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Jul 6, 2000

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Snellville, Georgia (Atlanta area)

Mar 14, 2007

#2

• Mar 14, 2007

• #2

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.

 

AaronG

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Jun 25, 2003

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#3

• Mar 14, 2007

• #3

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.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

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Mar 14, 2007

#4

• Mar 14, 2007

• #4

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.

 

Killercanary

The car that set the bar.

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Nov 29, 1999

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Altoona, PA

Mar 14, 2007

#5

• Mar 14, 2007

• #5

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

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Oct 3, 2003

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Bethesda, MD

Mar 14, 2007

#6

• Mar 14, 2007

• #6

dang ... mine were all around 150 when i did mine. was that an indication of carbon buildup?

 

AaronG

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Jun 25, 2003

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Mar 14, 2007

#7

• Mar 14, 2007

• #7

I didn't have the TB open, and I replaced each plug when I was done w/ the cylinder...

 

BlackVert

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Mar 14, 2007

#8

• Mar 14, 2007

• #8

yeah, that would probably make a difference. i had my tb open and i had all the plugs out

 

AaronG

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Jun 25, 2003

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#9

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• #9

Probably. Moreover, I'm satisfied with the overall consistency of the #'s.

 

Joe 5.0

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Feb 1, 2002

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Macomb, MI (metro detroit)

Mar 15, 2007

#10

• Mar 15, 2007

• #10

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.

 

AaronG

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Jun 25, 2003

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Mar 15, 2007

#11

• Mar 15, 2007

• #11

Joe 5.0 said:

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.

Click to expand...

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?

 

D

Danman765432

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Mar 3, 2006

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Nutley, NJ

Mar 15, 2007

#12

• Mar 15, 2007

• #12

when I did mine, mine were all at 150 give or take 1 or 2..that was on a hot engine

 

gcomfx.com

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Mar 15, 2007

#13

• Mar 15, 2007

• #13

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.

 

AaronG

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Jun 25, 2003

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Mar 15, 2007

#14

• Mar 15, 2007

• #14

gcomfx.com said:

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.

Click to expand...

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

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Mar 16, 2007

#15

• Mar 16, 2007

• #15

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.