All,
I've never seen one apart, but unless I'm confused, little to no quench action occuring in these engines. Afaik, since the chamber is full round, and the piston flat, there can't be. That's assuming [on my part] that the diameter of the bottom cut on the cylinder matches the bore diameter. I suppose that if the outside diameter of the bottom cut in the chamber is smaller than the bore, there may be a little quench action. Damned little though, imo.
Further, this is why I blabbered on about the possibility of using the slanted quench surface domed HTCC stroker pistons in these engines. Both to add compression, and allow for quench action. What SBCharlie is doing would also do both [welding chambers ifor a bathtub of other shape and creating a flat quench design].
Dave