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Compression Test Results

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Old Nov 15, 2009, 05:53 PM   #1
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Compression Test Results

What are yours?

my 1 and 2 were 105psi
3 and 4 were 95psi

low or no?

recently had the dipstick blow out.... but the catch can was clogged

so, are these low or average?
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Old Nov 15, 2009, 05:58 PM   #2
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I might be wrong, but i thought your readings should be around 150 for a healthy engine.
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Old Nov 15, 2009, 06:12 PM   #3
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ya, sounds low to me.
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Old Nov 15, 2009, 06:15 PM   #4
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looking for someone with experience. Thanks!
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Old Nov 15, 2009, 07:03 PM   #5
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I have compression tested a few 4b11ts now. The readings seem to vary from cylinder to cylinder, motor to motor, and even test to test on the same cylinder. It has to be something to do with the mivec on both cams floating around with the lack of or low oil pressure/control.

A leakdown test will show you the true health of your motor and show any problems that you may have.

Basicly if the cranking compression sounds healthy, the car makes the power it should, doesn't smoke or make noise, then its probably fine.

If you don't know what a car sounds like when cranking with a dead or low cylinder, pull one plug out and crank it and thats what it will sound like.
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Old Nov 15, 2009, 08:24 PM   #6
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Good information Eric. Thanks
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Old Nov 16, 2009, 05:51 AM   #7
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Quote:
Originally Posted by EricJ@AMS View Post
I have compression tested a few 4b11ts now. The readings seem to vary from cylinder to cylinder, motor to motor, and even test to test on the same cylinder. It has to be something to do with the mivec on both cams floating around with the lack of or low oil pressure/control.

A leakdown test will show you the true health of your motor and show any problems that you may have.

Basicly if the cranking compression sounds healthy, the car makes the power it should, doesn't smoke or make noise, then its probably fine.

If you don't know what a car sounds like when cranking with a dead or low cylinder, pull one plug out and crank it and thats what it will sound like.
nice eric, thanks. and This test was also done with the car totally cold.
I will do a leake down this week.
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Old Nov 16, 2009, 11:42 AM   #8
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I tested my car... They were about ~145 across all 4-cylinders. Tested on a hot motor.

IIRC, the values should be within 10% of 150. So between 135 and 165 PSI. This is for stock motor.
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Old Nov 16, 2009, 12:06 PM   #9
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Quote:
Originally Posted by Clipse3GT View Post
I tested my car... They were about ~145 across all 4-cylinders. Tested on a hot motor.

IIRC, the values should be within 10% of 150. So between 135 and 165 PSI. This is for stock motor.
Well unless you're at altitude like me... I see roughly 125-130 psi on my healthy 4B11. Then again, it could be my compression tester adapter, but I've always seen lower compression results up here because of the significantly lower (~12.7-12.8 psi) atmospheric pressure.
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Old Nov 16, 2009, 01:07 PM   #10
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Eric's explanation makes sense, something I didn't think of. With 9:1 compression, I was surely expecting 180+ psi per cylinder. Hell, my old 2g dsm with 8.5:1 gives me 175 across the board.
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Old Nov 16, 2009, 01:28 PM   #11
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damn thats low brother! the good thing is they are not too far apart from each other. It's suppose to be like 10 percent. You should be around 145 and up...make sure you do the test after you got the engine hot ....
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Old Nov 16, 2009, 02:07 PM   #12
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Originally Posted by XEVOX08 View Post
damn thats low brother! the good thing is they are not too far apart from each other. It's suppose to be like 10 percent. You should be around 145 and up...make sure you do the test after you got the engine hot ....
Hot vs. cold will make a ~5 psi difference at most on an engine with hypereutectic pistons like ours.
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Old Nov 16, 2009, 03:11 PM   #13
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Originally Posted by UT_EvoX View Post
Hot vs. cold will make a ~5 psi difference at most on an engine with hypereutectic pistons like ours.
well well, maybe mine is super low even still. i guess i need to warm it up and crank it again. looks like a leake down test will need to be done as well.

crossing fingers.
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Old Nov 16, 2009, 04:16 PM   #14
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Originally Posted by meat_EVO View Post
well well, maybe mine is super low even still. i guess i need to warm it up and crank it again. looks like a leake down test will need to be done as well.

crossing fingers.
How many times did you let the engine turn over while you were testing it? I like to do at least 6-8 compression cycles to get a good reading, else it will read low.
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Old Nov 17, 2009, 08:17 AM   #15
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Quote:
Originally Posted by UT_EvoX View Post
How many times did you let the engine turn over while you were testing it? I like to do at least 6-8 compression cycles to get a good reading, else it will read low.
Yeah make sure you get the engine HOT... like drive around for 20 minutes or at the least idle until coolant temp is 175*F. Then do a compression test. Turn it over more than 5x for sure.
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