Yep its oil residue. I haven't yanked the valve cover yet but I am fearing the worst. I highly doubt the valves are leaking that bad in one cylinder. I will update.

 

woooow ouch.. good luck man that looks pretty drastic

 

OMG! Keep us posted.

 

Yeah, keep us posted, very interested to see what happened.

 

#4 is the black looking one that definetly has some oil on it. its not fouled but does smell of some oil. The other one is out of the #1 cylinder. The piston doesn't look to be oil soaked though it looks similar to the rest of the pistons.

 

Could be a burned valve seat or a leaking valve stem seal. You'll have to remove the cylinder head to find out what is damaged.

The "cylinder #4 failure" refers to a scuffed bore due to extended running at high RPM with the old style oil jet banjo bolts.

 

^ thats better news then having to rebuild a piston.

I have never ran the car on the street to redline since being turbo'ed. That has only happened on the dyno and never for any amount of time.
I also put the new banjo bolts in before I installed the turbo so they should be good to go. The car only has 64xxx miles.

 

^ would a boroscope do the trick? Or will I have to yank the head?

 

If you can get a boroscope that can accurately see the cylinder wall, yeah. The cheaper -$300 scopes have a horrible field of view and require a clip on mirror to see at right angles. Not something you want to drop in the hole.

 

http://www.flexible-borescope.com/product/...deo+stik+-.html

This one has a better field of view than the manual versions.