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Old 03-15-2012, 12:03 AM   #1
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Unhappy Compression results: what do YOU think

Just did a compression test on a '97 for a buddy of mine. Stock motor with a Jackson Racing m45 5-6psi setup, beat to hell on 91oct pump gas.

Car is dead cold, injector relay removed so cylinders are dry too

first test
1: 175
2: 140
3: 160
4: 125

second test
1: 169
2: 135
3: 159
4: 127

Tests were done back to back, with a HF compression tester.
To me it doesn't look good, what do you guys think?
Should I even bother with a leak down or start yanking the engine?
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Old 03-15-2012, 12:08 AM   #2
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That fourth cylinder looks scary, and number 2 isn't great. Spec is what, 180? Does it burn oil, smoke, etc.? What exactly does "beat to hell" entail? Shitty tune, det., bad gas, or just fun driving.

With results like that, I'd be confident to condemn this motor. Or you could just run it until it takes a dump...... what was the reason you decided to compression test it?
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Old 03-15-2012, 12:18 AM   #3
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Originally Posted by 2ndGearRubber View Post
That fourth cylinder looks scary, and number 2 isn't great. Spec is what, 180? Does it burn oil, smoke, etc.? What exactly does "beat to hell" entail? Shitty tune, det., bad gas, or just fun driving.

With results like that, I'd be confident to condemn this motor. Or you could just run it until it takes a dump...... what was the reason you decided to compression test it?
I gues you want a Backstory lol:
he bought it about 2 years (that I remember) ago with the m45 and some dinky JR power card. It was absolutely terrible, and quite possibly slower than a bone stock car. He came to me about a year ago and had me install MSPNP and tune it. Real conservative due to the **** 91oct here in CA. Beat on it for a year and no issues.
Then he had some retard install a Honda Radiator on it to free up some room for a big FMIC that he also installed. Complete hack job, no shrouding, etc. Then decided it was a good idea to go do pulls on it to "measure the gains" lol. No re-tuning, no logging, nothing. The car overheated, blew a hole in the radiator, and started tweaking out.
He called me and I told him how retarded what he did was. So he asked me to diagnose the engine and try to undo the shotty work they did.


Here it is in all its glory


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Compression results: what do YOU think-img_00141.jpg   Compression results: what do YOU think-img_00142.jpg   Compression results: what do YOU think-img_00143.jpg  
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Old 03-15-2012, 12:26 AM   #4
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Time for a partout.... :P try the test with oil in the pistons? Big *** gap from 1 vs 4
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Old 03-15-2012, 12:39 AM   #5
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Looks great!

For a subaru. :\

Make him run more boost and make that engine die a good death.
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Old 03-15-2012, 12:48 AM   #6
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Radiator smaller then the IC ?
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Old 03-15-2012, 07:52 AM   #7
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Is that a radiator for a Honda motorcycle?
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Old 03-15-2012, 07:57 AM   #8
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Civic radiators are half the width of ours.
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Old 03-15-2012, 09:56 AM   #9
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They rings are fine.

Considering it overheated, I'd look into a leakdown and confirm the HG is bad.
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Old 03-15-2012, 10:11 AM   #10
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I would agree with Scott, but I would say the head is probably warped as well. Deck the head and get a new head gasket and you will probably see better numbers.
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Old 03-15-2012, 10:11 AM   #11
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Quote:
Originally Posted by curly View Post
Civic radiators are half the width of ours.
I know. I was JK.
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Old 03-15-2012, 10:47 AM   #12
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Leak down for sure - At least know what to blame. Especially if it overheated.. Head warping is what I'd look at.
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Old 03-15-2012, 10:53 AM   #13
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Let him sweat it out some and tell him hes fucked and needs a new engine

Seriously though I agree with the rest of the bunch and Id get the head decked and a new gasket. Its gonna have to get done anyway even if he replaces the bottom end.
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Old 03-15-2012, 11:21 AM   #14
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Hmm, so you guys dont think his rings are bad even having a huge swing like 175-125?
I talked with him last night, cool kid, just does stupid things (like drifting) sometimes lol, but he's ready for a full on longblock refresh......Said if I can save him some money and replace only whats really needed that'd be great, if not just rebuild the whole thing.

Guess I'll check leakdown tonight.
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Old 03-15-2012, 11:50 AM   #15
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is it consuming oil/smoking?
leakdown will tell you more info, but if it's burning oil decking the head and replacing the gasket isn't going to make much diff...
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Old 03-15-2012, 11:54 AM   #16
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Quote:
Originally Posted by 18psi View Post
Hmm, so you guys dont think his rings are bad even having a huge swing like 175-125?

no because the compression doesnt change between dry and wet.


oh wait, you did two tests, not a dry then wet....


what's with you guys?
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Old 03-15-2012, 12:03 PM   #17
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Aren't you also supposed to do compression tests warm?
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Old 03-15-2012, 12:05 PM   #18
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Quote:
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no because the compression doesnt change between dry and wet.

oh wait, you did two tests, not a dry then wet....
Exact same way I read it. I (wrongly) assumed the second test was with a dab of oil.

Leak down is the only way to know for sure, but you could throw some oil in there too after the leak test to help confirm if the test shows rings are good.
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Old 03-15-2012, 12:05 PM   #19
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that too.

i love how our senior members don't even know how to turn a wrench
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Old 03-15-2012, 12:08 PM   #20
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I'll re-test again today and see if there's a difference with warm/wet.
Thing is, I don't think the difference between 1 and 4 (and the others) will change. They will probably all go up in numbers, but not increase in consistency.

But I'm just guessing at this point lol
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