UrbanKnight

So, just doing a wellness exam getting ready for this up coming season with the car. Here is what I discover/issues:

1. After my last open track day, I got a P0302 misfire code, also got it on startup today and "heard" the misfire- We pulled, #2 plug, and the tip had cracked off- Well, that explains the misfire... That cylinder has compression of 150, so good there.

2. All plug threads have oil on the threads, but not the tips (I think* that means valve guides are worn...)

3. After a hard track session, I have blowby of about 8 ounces in my catch can. Originally, I was going to redo some breather on the driver side fill cap to help get some of the crankcase pressure off the car. Car makes 700ish to the wheel, pushing 15#'s of boost, so I know the pressure is up and that is an issue.

4. Compression test results are below, basically, 150ish cylinders 1-5, 110 in #6, 135 in #7 and 8.

So.... Do I do a motor rebuild now, or swap in some new plugs, redo the crankcase breather system and let it ride till she blows/if she blows?. The car runs strong as can be, but being that I track the car 12+ days a year, its just a matter of time, just not sure now is or isn't the "time"

K B Vettin

if you do it now you can probably get away with a ring and hone job. if you wait then you'll probably have to bore out the cylinders and get new pistons. personally i'd wait to see if it gets worst then rebuild with a small bump in compression then you could run less PSI and make the same power which would create less heat. just my .02

UrbanKnight

Thanks...

I am heading the same thought- I have no problem doing a full build when the time comes, and part of me says, meh, just beat it to death and see how she fairs...

The logical fixer side of me says BUILD IT NOW!, lol

The boss

Have you done a wet test to see if your problem in from a valve or ring? I normaly pour 1 once of motor oil in the cylinder, cranck it a few turns without the plug to remove excess oil (without starting the engine), then test compression again. If compression stay low or very little difference, it more a valves problem, if compression get way higher, probably a ring problem. This test should be perform on a warm up engine. I know most of you probably know about this but it may be god info for less experience diy guys.

C5kid

Funny... Exact same cylinder that failed on me.

The plasma moly rings can't take the heat. Should of been a SS top ring from the factory. The plasma moly ring just flakes apart from excessive heat.

So if you guys are getting a lot of oil in your catch can, probably getting a bunch of blow by from some cooked rings.

I re-ringed my motor with SS top rings after getting a low compression reading and pulling a piston to find this.

UrbanKnight

Thank you C5 kid!!!

ace32x

Interesting results. Sorry to hear your down low on one.

Recently had one done on mine and they were a little low aswell but all even. Been keeping an eye on it. They were all 135-145

UrbanKnight

Ace- I'm not upset about it. It's the nature of the game we play when you push these are hard.

Vito.A

I would do a leakdown test on it first. A leakdown test is more accurate than a compression test. It will tell you a percentage of leak and if the leakage is from intake valve, exhaust valve, or the rings just by listening to where the escaping air is coming from (throttle body= intake valve, exhaust= exhaust valve, crankcase=rings).

whatcop?

Same 3 cylinders on my car