piston failure???

[themeanest240]

I have a redtop sr20det, i took the head off to replace the H/G.last summer i was running 15 psi on gt2871r, enthalpy tuned.my timing was off for about 2 weeks, pretty hard detonation...still ran strong after retimed it to 15 deg. BTDC.for 3k miles it ran strong, ran 12.6 quarter mile. no smoke, no oil burning.driving it pretty hard also. my oil catch can did consume oil fairly fast, i thought it was just because i was at the track beating it.i didnt think to compression check it before i ripped it out.and now im cleaning my block, noticing damage on 2 pistons.i have pitures, its just too hard to see it.

My best explanation of the damage would be, on one side its raised, really rough, (80-120 grit sandpaper) but its still round in the clyinder. the sleeve or cylinder wall is rough right where the piston is rough.The cylinder wall doesnt seem too bad. its just rough at the corner of the wall and the top of the block.

I dont have the tools to compress the rings, and im scared to take it all out. I dont have any measurement tools or any of that stuff, let alone a trustworthy machine shop.

Please help me out. thanks NICO!

damage on the left side of this photo

Modified by themeanest240 at 7:38 PM 2/13/2010
Modified by themeanest240 at 7:39 PM 2/13/2010

[rioredstang]

I think you need to pull the pan and pull the pistons out. The area that shows signs of detonation is where the quench of the head is. I saw a article in Turbo Mag they opened up this area to stop this problem. If it has detonated it can break the ring lands, also it hammers the rod bearings. Now is the time for inspection not after it hangs a rod out.As for tools, go to auto parts store and borrow or rent them.

Check out this pic.http://image.turbomagazine.com...s.jpg

[themeanest240]

I think you need to pull the pan and pull the pistons out. The area that shows signs of detonation is where the quench of the head is. I saw a article in Turbo Mag they opened up this area to stop this problem. If it has detonated it can break the ring lands, also it hammers the rod bearings. Now is the time for inspection not after it hangs a rod out.As for tools, go to auto parts store and borrow or rent them.

Check out this pic.http://image.turbomagazine.com...s.jpg

The pans are off, the cylinder wall is pretty clean on that side.So i couldnt see the ring lands being damaged, i know they need to come out to hopefully deck the block to get right of the scoring.Ive just never taken pistons out and i know looking it all up in the internet isnt going to tell me everything..

The head has the same scoring, and i have no clue how to rip that all apart.

Thanks for your help

[rioredstang]

You don't have to take it apart. You will need a good Dremel tool, some good masking tape, and newspaper. Tape up the intake and exhaust ports. Tape the cams and springs area with newspaper. Tape the combustion chamber with a couple strips of tape to prevent scoring the valves.Use your old head gasket and trace the o-ring outline of the gasket on the head. Now very carefully start removing the material around the chamber. Take your time. When it looks similer to the pic your done.After you get through untape the head and pressure wash it at a car wash. Then air dry and coat with WD40 till you install it.

[themeanest240]

Im not really understanding, i know what you mean by tape everything off, but with a dremel tool what am i suppose to do? try to open the combustion chamber like they did in turbomag?that doesnt sound like a very good idea...

[rioredstang]

By removing the metal in the quench area you stop the detenation from starting and doing damage to the head and piston. The small area between the head and combustion chamber is the problem. Read the article in the link and it may explain some of the problems.

http://www.turbomagazine.com/t....html