Originally Posted by 1QwkSport2.5r

If I have two engines that I’m picking from for a model, I like to run them open faced to see the real apples. It’s not always about the power, but if an engine turns your prop at an acceptable rpm and not have any tractability issues with open exhaust, then that is the better candidate. OS historically has made powerful sport engines, but with some caveats. Probably the worst one, IMHO, the giant carb and constipated muffler setup. Runs good on the muffler, but falls on its face without the muffler. Think “PowerBox”.