Did a compression test today just for the heck of it. My car was tuned weekend before last and made 330whp and 317wtq. Now, before the tune, my car has always been a slow one. My little brothers 230whp WRX pulled 2 cars on me when I was stock. So I think my car has always had this problem. Anyways, it reads like this.

180
180
150
180

The car runs good, idles good, doesn't smoke at all, and burns NO oil. I have no plans to rebuild it anytime soon, so I guess I am just going to live with it. Oh yea, plugs have always read good too, no detonation. Is it possible there could have been an assembly error from the manufacturer that could cause this cyl to be low? What would you guys do if you were in my situation? BTW, my numbers for the dyno day were on par w/ everyone else w/ the same mods. I have done the test about 6 times now and the same cyl is low by about 25~30psi everytime. Oh yea, and I poured a cap of oil in the cyl and the comp. jumped to 180, so according to the manual its a comp. ring or cyl wall problem.

 

What does pouring in a cap of oil do?

 

Im not sure, but it has always been a good test to see if its your rings.

 

Dont You Have Factory Warrenty?

 

The cap of oil trick allows the oil to form a temporary seal around the edges of the piston during the compression test. This more or less allows one to isolate the rings or a valve as the most likely cause of the leak.

 

I might add that unlike a V8, if there is a problem with one cylinder on a 4-cyl engine, it will definitely be down on power.

In this case, that one cyl is down some 17% on static compression, which is significant. It may very well create excessive oil consumption and a good deal of blowby (fouls your IC and such) in addition to being down on power.

 

I have the factory warranty but there is no way they will warranty this due to the mods in my sig.

 

That depends...maybe not.

Considering the potential costs involved otherwise, it may be worth your while to reinstall the factory intake, lose the MBC, and maybe reinstall some exhaust pieces (if you have them). The cams aren't obvious, the fuel pump is invisible, and the flash is probably 'invisible' for all practical purposes as well.

I wouldn't feel bad about pursuing warranty work because you described the car as having always been 'slow', which implies a defect from the factory. At any rate, all they could possibly do is tell you "no", so you have little to lose except a bit of elbow grease.

 

But here is the thing, the car isn't down on power anymore. Stock....yes. However, with my tune, I made pretty much the exact same power as everyone else w/ my mods that day. I was down 5hp or so and about 12ft/lbs compared to everyone else that was there with my exact mods....there were about 4 other evos there like mine. I am really not that concerned as it appears the car came like this and has not been getting worse. I will keep an eye on it as the miles pile up, but if it starts getting worse, then she is getting built.

 

Okay well I just compression tested my brothers Evo and his came out EXACTLY like mine. So, I am assuming there is some annomoly in cyl 3 throwing the comp. guage off. BTW, his car ran a 12.89@108.2mph with a TBE, intake, and dynoflash....aka, its not a weak evo. Guess everything is fine and this comp. guage is just crap.

 

Yeah honestly if ur making 330 thats about where you should be with your mods

 

I was going to suggest error in the gauge you were using. That's probably it. Oh and I've never actually heard someone say that their Evo was "Slow." That was the first time I've heard it. Lol.

 

The gauge was probably designed by an Auburn engineering grad.

Roll Tide!

 

Ha! War Damn Eagle.....and I just so happen to be senior in Mech. Eng. there.