Worn piston

[Botus]

That bore has picked up the piston which suggests overheating. The wear on the bearing nearest the piston definitely suggests a bent rod as the wear seems uneven side to side.
The big question is did the overheating result from the bent rod or did the bent rod result from increased bore friction caused by overheating?
Pity we can't see the thrust faces of the piston.

this happens as the rod bends, as I say pretty sure always self inflicted, often goes with the explanation "its wasn't overheating I'd only driven 100 yards"

yes, on full throttle with a stone cold engine....

 

[Jim2]

So moral of the story is that all mapping is not necessarily good.....beware !! Having said that, last time I fitted pistons ( and that was not yesterday or the day before either ) they bore very little resemblance to the piston in this post...looked more like half a piston, measuring from the top to the bottom. Innovation and "improvement"???

 

[Blobcat]

So moral of the story is that all mapping is not necessarily good.....beware !! Having said that, last time I fitted pistons ( and that was not yesterday or the day before either ) they bore very little resemblance to the piston in this post...looked more like half a piston, measuring from the top to the bottom. Innovation and "improvement"???

To meet the needs and desires of owners and the regulations of government. 500+ bhp, 60+mpg and ~Zero Emissions...
So things have to get smaller and lighter which puts more stress on them so they fail.
The engine in my 911 can be fragile and if you hear a tick, tick, tick at idle it’s a ~£14k bill... however get it fully warm - oil and water (nice gauges for both) before you cane the backside out of it and it will run for many 10’s of 1,000’s of miles with no issues (and 24 month services)