ORIGINAL: kersplat
Actually we used Veco .19 engines in the 1970's. They had the Dick McCoy piston and sleeve, The piston was the Dyke ring style and these setups lasted only about 10 hours. And that was using the old school fuel with about 20% castor oil.
Were these special engines because all the Veco 19's I've heard about had a cast iron piston. The old McCoy 19 RR had a twin ring piston (
AFAIK) and so did the ETA 19. I've heard of a home made racing .15 with rings but that's the smallest engine I know of that used them.