I started listing the different cylinder liner and piston material combinations, but the piston rings are a significant factor in friction losses and wear.
Piston rings should be as thin as possible to reduce contact area.
I have made cast iron piston rings, but not for a long time. I made them by firstly turning a cast iron ring to size. The ring is then split and filled to give a small clearance on the ends so that the ring can be squeezed into the liner. The ring is then held in a fixture to keep it flat at the same time being expanded with a small piece of steel between the ends. I then coated the ring in a brazing flux to stop it oxidising whilst being heated to cherry red.
This is where my memory goes as I cannot quote remember how hot and for hope long – can anybody help here?
This link describes using the Trimble method: Feeney Construction