[brettco]

Originally Posted by olddog

I pulled an aluminum block 4.6 ltr modular engine, out of a 96 Lincoln that had 105K miles on it. All 8 pistons had the compression ring gaps aligned, but not the oil rings, as you described. The gaps on all 8 pistons were located in the same spot (say at the 6 O'clock position), as I was quite puzzled by it. At the time I assumed it must have been assembled that way, because I couldn't understand how 8 pistons would have all ended up in the same position.


So this begs the question, why not go to the gap-less ring technology, and eliminate the compression ring gaps?

What is wrong with gap-less rings? I never hear any builders say much about them, and as far as I know, I never heard of a new car manufacturer using them (which they may).

My sprintcar engine builder said gapless rings seal too good and can float the ring off the cylinder wall where a gapped ring will let the pressure past and let the ring work. He said everyone gets off on zero leakage on the breakdown gauge but 100 psi isn't a piston rings real world environment. A running engine has very high cylinder psi.