Hello everyone, I wanted to get some opinions on my recent compression test results. I’m already assuming that the general consensus will be engine rebuild or a new short block. Here are the compression results

Cylinder 1 = 125psi
Cylinder 2 = 95psi
Cylinder 3 = 150psi
Cylinder 4 = 105psi

I know that the standard is 145psi, minimum is 92psi, and the variance should be around 14psi so these numbers aren’t looking good. The engine has 140k miles. The car ran completely fine before the test, no misfires, it didn’t smoke at all, no oil in the coolant, and little to no oil consumption. I had my buddy do the test and he did tell me that he did it with the throttle plate closed and the engine temperature was under operating temp so maybe that’s why the numbers are all over the place? I do plan on taking it to a shop to get the compression retested and have them do a leak down test. Just want to see what you guys think before I put the car non op and save up for a rebuild or a new short block.

 

My compression numbers were worse with my evo 9 and I drove it for another 20k miles over 4 years before rebuilding lol. The car had 168k miles before the original motor was pulled. It ran all the way to the day we took it out for the rebuild.


memory serves me right I had low compression in cylinder 1 & 3. Like very low below 80psi.

the other two cylinders were about 125.

My car didn’t smoke, and I put a very conservative tune on it after finding out those compression numbers.

clearly these engines are very stout. So I wouldn’t worry too much but saving for a rebuild is a good idea. Since oem short blocks are like impossible to get now.

 

Jahtoot is on the money. Just start saving of a rebuild and plan to do it in the future. If its still running well, it isn't an emergency to get it rebuilt.

 

Thanks guys. Makes me feel a little bit better about it lol. Only decided to do a compression test was because I was about to take my car to get tuned and wanted to know what type of tune my car could handle depending on how healthy my motor was. Just recently swapped out my stock turbo due to shaft play for a 20g built by Tyler Gennari. After 8 years of ownership and keeping it keeping it stock I’ve finally decided I didnt want to be stock anymore lol

 

that just means crankcase pressure will be higher than normal... that might break your turbo seal or put oil into your intake pipes

 

Lol. Yea I wouldn’t worry. Just have a conservative tune (no knock)

I was still getting knock counts on my if I drove hard in the high rpms. Magically the motor kept together lol.

on engine tear down. Only bearing #1 had wear (could of spun)

everything else was in great condition for the block.

the head was in immaculate condition (completely stock)

the tuner I went to saved the car. Upon tuning he noticed something was off and that’s how we came to a compression test. At that point he just tuned for minimal knock and advised I don’t push the car hard.

your car sounds way healthier and way better compression numbers than mines lol

 

Those compression numbers fail a pre tune inspection at my shop.

We do allow down to 120psi, but more than 10-12% variance is a no go.