I was just going trough a thread from another site (don't worry, my loyalty is here). A question was brought up about the counter throws on a crankshaft going supersonic and at what rpm it takes to achive the FPS to get it to that point. I chuckled when I read it because the issue of the whole mass was not considered. Back in the Eighties, we sat around one Friday evening and pondered this situation and discussed what effects it would have on the reciprocating assembly inside the crankcase. We did a lot of geometrical computations and we discovered that some engines could achieve supersonic vortex and some where not affected at all. Question is, At what RPM can you achieve the critical cross over point to meet the requirements of supersonic stall/vortex inside your crankcase. Just food for thought and silly wondering. P.S. we figured it out and it was just a time killer for us.