Originally Posted by Custom10
OK so the coating must be 0.005 or so all the way round and it does actually squish down under some pressure, perfect fit, hmm LS1 magic,
So the middle is big and each end top/bottom is smaller?
Coating is thinner than that, but yes. you are correct.
Just some #'s for example off the top of my head, not in particular to the LS question, just general info:
Very bottom of skirt might only be .0005" smaller than the bore, but the top of the piston might be .010"-.015" smaller(some forgings are .035" smaller at the top) than the bore. A lot more thermal expansion at the top, this is why they are barrel shaped. Fattest part of the barrel shape is usually only about 1/2-1" above the bottom of the skirt.