I would like to kick this comparo between Mustang 50 and the Zenoah G45 around a little more. There is a vast difference in their bores and strokes. The Mustang has a 1.26 in. bore and a 1.69 in. stroke, which in my mind makes it a longstroke engine and the G45 has a 1.7 in. bore and a very short 1.2 in. stroke. It would seem like the Mustang should turn a bigger or higher pitched prop at a lower RPM and develope about the same thrust as the G45. I hope someone out there is more engine wise than I am, my experience is almost entirely with glow engines.