6 bolt melted piston/ overbored?

[_4g63_]

So I just got done pulling the head on my 6 bolt swapped 96 gsx after finding coolant in the oil pan. In the 2 cylinder there's damage to the cylinder wall and on the piston crown.

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Is this from detonation? I never drove the car I got it in a trade, it was running but not very well, it poured oil out of the bottom of the front case, and smoked out of the cheap filter on the valve cover.

So I'm wondering if just a cylinder hone would be enough to repair the block, or would I have to bore it over and installed bigger pistons. The pistons in there now are ross 85 mm.

 

[Jay 97 GSX]

Wow, thats messed up. Hopefully it can be rebored.

 

[bastarddsm]

You can probably clean it up with muratic acid, and then lightly hone it. Really needs to be done at a machine shop with a rigid hone, then they can measure if it needs to go oversize. typically for a street car you don't really want more than .005" ptw on a forged piston. I have run some at .006" but they are noisier.

Get it cleaned up before you order a piston. And yes that damage is from being run lean under detonation.

 

[Murdertalon]

You can probably clean it up with muratic acid, and then lightly hone it. Really needs to be done at a machine shop with a rigid hone, then they can measure if it needs to go oversize. typically for a street car you don't really want more than .005" ptw on a forged piston. I have run some at .006" but they are noisier.

Get it cleaned up before you order a piston. And yes that damage is from being run lean under detonation.

Wonder if the previous owner ran low octane gas, or it was running real hot?