How bad does this piston look?
 

So I pulled my engine apart due to a bad valve leak in cylinder 2. Once i had it apart and all cleaned up i noticed this damage to the piston in cylinder 3.

How bad does this look to you guys? It looks like it sucked up something right? not detonation?

I have not found any damage to my turbo. Cylinder 3 had less than 10% leakage and 160 psi on compression test.

something definitely got in there, how does the head look?

I can't find any damage to the head.... let me go take another look.

I lied, head shows similar damage. I'm not planning on reusing the head though.

my question is, can i use this piston or is it a ticking time bomb?

Shouldn't be a problem if you clean it up. You've gotta get all the raised edges off around the divots. Take a file to it, and level that surface off without removing too much of the original surface.

Looks like there is a tiny bit of scoring on the cylinder wall... couldn't really get a good picture of it. I could not catch it with my finger nail but I could feel it with the tip of my finger.

Does you haz both throttle-body butterfly screws still?

First thing i checked. Both are still there.

How about piston rings? Those are very similar marks to what a small broken ring made on my piston..

I think an rx7 injector pintle cap entered one of my cylinders like 2 years ago. Car still runs ok though.

Well i think you can still run it but i wouldnt do a high boost or low octane tune. U would prob have pre ignition with them edges.

I say time to build a block

Can't see any ring damage, but the pistons are still in the block.

https://www.miataturbo.net/attachmen...ine=1336365523

http://www.boostedmiata.com/random/pistons/IMG_6440.JPG



not as bad, but I'm still using this head.

Yeah i'm going to use just the bottom end. Have a rebuilt head sitting on the shelf ready to go on. Just need to replace the rear main seal and clean up the block. Thanks for all the help and suggestions.

it looks like a flaked ring, I would pull that piston, and check the rings out.

If it all looks good, slide it back in and go on with it.

Dress the sharp edges off like has been stated above.

Would it be ok to pressure wash the engine with the head and oil pan off, and the rotating assembly still in? It won't hurt anything right?

Nope, as long as it dosnt sit up too long and rust.

Build it and get oil in in asap and get it primed.

Any imperfection will cause a hot spot and more detonation.

Unless time and care is used and any high spots removed.