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Hello all. I have tore my engine down and started reassembly. Upon removing the old rings I found damage that I haven’t yet come across and was hoping someone more knowledgeable could tell me what generally causes this kind of damage. This was only on the top ring and I found it on 6 out of 8 cylinders (1 cylinder I can’t be sure because I threw it away before I noticed the issue on the others)
the combo is a 5.3 forged internals and a 85mm turbo on 17lbs it made 833hp. I pulled the engine apart for reasons unrelated to the rings.
This only happens to a top ring that’s got way too hot. It’s not uncommon for boosted engines to do this, hence is why you run them fat (rich)…to help keep domes AND top rings comfortable. It’s a fine line. Run it too fat and your washing cylinders down…which will delaminate the top ring also from a lack of lubrication, which equates to too much heat in the top ring naturally. I’m sure your skirts are marked up also from the flakes in the cylinder. Tune is everything.
What Scott said...
To add from a 20yo post: "Moly flaking is typically a product of DETONATION, ring butting, another story will cause the piston to fail 9 times out 10, lifts the top ring land off the piston. Moly-flaking is good indicator you better get a hold on your tune-up, because it ain't right. Your rod bearings will indicate this as well."
What Scott said...
To add from a 20yo post: "Moly flaking is typically a product of DETONATION, ring butting, another story will cause the piston to fail 9 times out 10, lifts the top ring land off the piston. Moly-flaking is good indicator you better get a hold on your tune-up, because it ain't right. Your rod bearings will indicate this as well."
What do the plugs look like?
Any data logs?
unfortunately I don’t have any data since the reason for the tear down was a lifter twisting and wiping out the cam. I do however know the owner (me) and I know I drove it when I first put it back together without the wastegate plumbed properly and it was spicy. It’s since been dyno tuned, I assume the damage then is from my own idiocy and excitement. I appreciate the help. I just hadn’t seen damage like that before. Luckily it didn’t mess anything else up.
This only happens to a top ring that’s got way too hot. It’s not uncommon for boosted engines to do this, hence is why you run them fat (rich)…to help keep domes AND top rings comfortable. It’s a fine line. Run it too fat and your washing cylinders down…which will delaminate the top ring also from a lack of lubrication, which equates to too much heat in the top ring naturally. I’m sure your skirts are marked up also from the flakes in the cylinder. Tune is everything.
thank you for the help. I assume this is damage from before. I have since had it tuned but there was a time when I hooked the wastegate up wrong and it wasn’t finely tuned. I hadn’t seen ring damage like that before.
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Piston ring damage identification 
