Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi Ben,....How much engine Rpm or "hits" per min difference from your compression ratio mod have you noticed ? .....I've been considering dropping my M90's  9.5 C/R  down to 4.5 or so & was wondering  if the resulting lowered engine speed & reduced hits per min is noticeably worth the effort ?? .... thx, ....tom.