Hypereutectic pistons and failures related..
Are the pictures the passenger side? 4" stroke and shorter pistons will side load and leave marks where the std stroke and tall pistons rarely do. What I see might being issues are too much piston to wall, possibly contaminants in the oil, and the cylinder wall finish looks too rough.
I'd be looking at piston to wall of .0015-.0025 and the finish should be a lot smoother. This will help with giving the skrts a smoother surface so there is no material transfer and let the limited oil do a better job of protecting against the skirt contacting the wall. See attached.
Are the pictures the passenger side? 4" stroke and shorter pistons will side load and leave marks where the std stroke and tall pistons rarely do. What I see might being issues are too much piston to wall, possibly contaminants in the oil, and the cylinder wall finish looks too rough.
I'd be looking at piston to wall of .0015-.0025 and the finish should be a lot smoother. This will help with giving the skrts a smoother surface so there is no material transfer and let the limited oil do a better job of protecting against the skirt contacting the wall. See attached.