Randal

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?

94AWDcoupe

iTrader: (125)

great compression. ready for bigger turbo. like a 3076 on e85.....

rjfg

iTrader: (13)

Nice all across the board

Randal

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.

EvocentriK

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.

aggieEVO

iTrader: (11)

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.

barneyb

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.

Randal

Even in E85? It's practically a fuel additive cleaning everything it touches lol

cmspaz

iTrader: (1)

WAT.

E is a terrible solvent, but it doesn't produce the soot pump gas does, that's why your motor stays clean.

SDevo13

iTrader: (6)

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.

barneyb

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.

High_PSI

iTrader: (50)

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.