I just bought another NovaRossi engine for this heli. It is a .20 side exhaust engine. Cost was $100 so I will not feel bad when I cut the crank to fit. It does not have the power of the .21 but I think it will work fine. Also, the cooling head that I have will work on this motor. And, the bolt pattern is the same for mounting. I chose this motor because of the price and because it is side exhaust. On a pipe, it should be about 1.9hp @ 29,000. If I need more, i'll port it and bore out the carb. Next step is to shorten the hub that goes on the crank. I'm going to try and make the installation as tight as possible so that the engine hangs down as little as possible. I'll have to modify the engine mount I made by making it shorter as well. Also, the landing gear mount will have to be taller because the engine will still hang down a bit. And, I will have to trim the cooling shroud to fit the bigger cooling head. Ill try and post pics when all is done