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Just finished compression testing on my Evo 8 with 103k miles.

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Old Aug 23, 2013 | 03:57 PM
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Randal's Avatar
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Just finished compression testing on my Evo 8 with 103k miles.

I have an Evo 8 with 103k miles, dont know if the motor was built or not previously. So I did a compression test how I read in the forums and this is what I got.
1st 165psi
2nd 165psi
3rd 165psi
4th 160 psi

Wet as in added a couple of drops of oil in cylinder before testing.
1st 170psi
2nd 165psi
3rd 165psi
4th 165psi

I read the evo 8 by factory is at 163psi? What the hell?
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Old Aug 23, 2013 | 08:51 PM
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great compression. ready for bigger turbo. like a 3076 on e85.....
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Old Aug 23, 2013 | 09:27 PM
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Nice all across the board
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Old Aug 24, 2013 | 05:01 AM
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Does this mean maybe the motor was recently rebuild? Because at my mileage it's impossiblemtomhave more compression then when the car left the factory.
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Old Aug 24, 2013 | 05:24 AM
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All compression testers read differently. You use them to give you an indication of ring/cylinder health and differences between cylinders rather than looking really hard at absolute numbers.

Mine has 50,000 kms and I ran 160/160/160/160 a couple months ago when I did mine.
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Old Aug 24, 2013 | 06:53 AM
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My tester read 185 for each cyl. It just depends on the tester. The thing to be happy about is the consistency. You don't have a bad cylinder.
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Old Aug 24, 2013 | 08:04 AM
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Compression can increase over time due to burnt fuel and oil deposits in the cylinders. In car engineer's lingo this is known as octane creep.
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Old Aug 24, 2013 | 08:53 AM
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Even in E85? It's practically a fuel additive cleaning everything it touches lol
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Old Aug 24, 2013 | 09:28 AM
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Originally Posted by Randal
Even in E85? It's practically a fuel additive cleaning everything it touches lol
WAT.

E is a terrible solvent, but it doesn't produce the soot pump gas does, that's why your motor stays clean.
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Old Aug 24, 2013 | 10:26 AM
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It would be easy enough to pull your oil pan. Aftermarket rods (which everyone does with a build since the stock ones are the weakest link) would be very easy to spot. You won't be able to tell if its built just from compression tests unfortunately.
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Old Aug 24, 2013 | 03:50 PM
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Years ago the standard multi-weight oil used in gasoline engines was 10W-40. The reason for the switch to 5 or 10W-30 wasn't just for gas mileage it was also because 10W-40 oil tended to cause a lot of deposits. Cars, as they accumulated some miles, would start to knock.
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Old Aug 24, 2013 | 05:36 PM
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Originally Posted by 94AWDcoupe
great compression. ready for bigger turbo. like a 3076 on e85.....
Who still runs a single scroll 3076 this days with the just as powerful if not more so and faster spooling FP & BBK turbos?

That is a very consistent readout, very good numbers and a healthy motor.
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