I performed a compression test the other day. Warm motor, only one spark plug out at a time (I see a lot of people recommend taking them all out at once) and got these results:

130/130/140/145

145 is factory spec on the Evo IX's from what I've seen and minimum is about 90 psi.

Are these results indicative of a head gasket that is starting to fail on one side? Will switching to ARP headstuds be of any help here? Is it even worth worrying about at this point?


I'm tuned at about 24psi, so the ARP head studs are probably a good idea either way

 

Other information that may be of use:

Car is at 60k miles, just did the 60k service.
Mods: Exhaust, intake, boost controller, fuel pump and a tune

 

Specs

Compression Pressure
Standard value (at engine speed of 250 r/min) ............ 1,000 kPa (145 psi)
Minimum limit (at engine speed of 250 r/min) ................ 637 kPa (92 psi)
Variation Limit ............................................. 98 kPa (14 psi)

 

Is it burinign coolant or is it filling the coolant overflow with air? Those are some signs of headgasket failure. I wouldn't worry about arp's at this point. When you did the test was your throttle plate open?

 

No coolant issues as far as I can tell. I will pay closer attention to that though. Throttle was wide open for the test. Oil isn't cloudy at all either.

 

sounds like bad rings to me, do a leak down test and see how that goes. if it were a hg it would be like 115 125 135 150 but theyre pretty even.

 

The engine is showing a little wear, which it should after 60K. So, I say, normal.

There have been some Evo engines ruined by injector issues, either not working or clogged. I've noticed clicking noise on two occasions in the 3000 rpm range. Each time I dumped in injector cleaner and the noise went away. Maybe they have bad gas here - dunno. So, I am thinking that maybe this would be a good idea to do this as a maintenance item once or twice a year. Run a cylinder lean and you soon have no compression.

 

I haven't ran any of that through my fuel tank since I've owned it so that's probably a good idea regardless.

 

Yea sounds like it may be your rings are a little worn. I just did a compression test with my weisco stock compression pistons and had 150 even across the board

 

Those #'s sound fine to me. I wouldn't even worry about it unless its below 115...