martinPL

iTrader: (3)

Hi,

I was wondering about compression in Evo IX MR engine. How many atmosphere
should healthy engine has??

Thank's
Martin

nismos13sleeper

well first question is how many miles does ur motor have, does it have a bunch of timing thrown at it and how much boost is being run through it. depending on those numbers would reflect what the compression test roughly should be. i dont know how much psi they put down stock it mihgt be somewere around 180-200 psi. but mainly u want somewhat level number across all 4 cylinders

something like 162,167,165,160 would be fine/ u dont wanna see like 140,165,162,135 that means u have serious blowby issues/vavle sealing issues also.

YogSaahoth

iTrader: (9)

According to the service manual:

-Standard value is 163psi or 1128kPa
-Lower limit is 138psi or 951kPa
-No upper limit is given, but like the guy above stated, it depends on car mileage and may be as much as 200psi.
-The key is the difference between all 4 cylinders. No pressure value should deviate from another by more than 14psi or 98kPa.

*Note..compression testing should be done with the vehicle warmed up (coolant temp 80-95*C)

Hope this helps...I trust you can convert psi or kPa to atm

ch1215g

iTrader: (3)

So 165 165 165 165 is good compression in a sense?

Aaron20

I had a Compression Test and a Leak Down Test, my results were Cylinder #1: 175PSI Leakdown 0%, Cylinder #2: 180PSI Leakdown 3%, Cylinder #3: 175PSI Leakdown 0%, Cylinder #4: 180PSI Leakdown 3%. The Leakdown test was a 3 hour test. This was on an Evo 8 motor but the 9 motor should be pretty much the same.

student driver

So if I have my engine checked should I ask for a leak down test or do they do it/suppose to, anyway.
Also I thought I heard someone say it would be different pressures "plugs in" and "plugs out"???

Aaron20

you cant really do a compression test with the plugs in as the tester goes into the spark plug hole. I would recommend a leak-down test if your going to get a compression test done, but thats my opinion.

YogSaahoth

iTrader: (9)

Well you have to remove the spark plugs to have access to the combustion chamber. Whoever you heard that from was probably referring to whether or not they left the other 3 plugs in while testing each cylinder. Sure, readings may be different compared to if all 4 are removed during the testing (seems unlikely though). I have always taken all plugs out and tested that way. There is a large range of acceptable compressions, so the value itself isn't as important as the consistency between cylinders. Mitsu manual says remove all plugs and then test each cylinder

Aaron20

I agree with this, the compressions might be different but I can't really see why as each cylinder is an individual cylinder and there should be no bleed over. The reason you take out the spark plugs in all cylinders is just in case you have blow by the excess pressure has a place to go and not out an area you dont want like the head gasket...

YogSaahoth

iTrader: (9)

^Exactly...

Boosted Tuning

iTrader: (12)

That is the info for the EVO 8, which is different then the EVO 9.

EVO 9 info:

Standard value: 1,000 kPa (145 psi)
Minimum limit: 637 kPa (92 psi)
Difference Limit: 98 kPa (14 psi)

blaze-619

iTrader: (3)

Is it bad if you do a compression test when its cold?

martinPL

iTrader: (3)

Ok guys. I have different scale in PL.

Compression for Evo IX should be 9 atmosphere and I have 9 in all cylinders

Evo IX MR with 46 000 miles on it.

Thank's

nismos13sleeper

cant help with that lol dont know enough about different values

xRoguex

iTrader: (15)

9-10atm's