And OS isn’t even true ABC! True ABC - if done properly - can easily out-power a ringed engine simply due to superior piston sealing if all else is equal. True, a piston ring will freshen up a ringed engine, but a simple liner pinch can bring an ABC engine back to life if you cannot machine a new piston (what really wears out in an ABC engine).

My favorite engine constructions in order of greatness in my book:
Ferrous Iron/Steel, AAC, ABC, Thunder Tiger ABN, Dykes ringed, and lastly traditionally ringed.

I sold many of my ringed engines, and the ones I have that could be converted to ABC were. I have a few ringed engines that I’ll keep as they are because they’re so stupidly reliable (they all have Bowman rings installed and a spare Bowman ring for each.. I’m a hoarder. )