My S75 is a very user freindly engine, a little more so than my g90, the 90 will pull a 14-6 zinger 10,400 and the 75 will only make 10,000. I used both engines in the same airframe and the power differences diminish if you prop the 75 to turn about 1000 more rpm. The 75 with a 12-8 performed about same as the G90 with a 12-10. The 90 WILL cook a piston faster if run too lean for too long.