Actually it sounds a lot like a four stroke but it is quick, supposedly it will turn a 10x5 at 17,000 rpm. My friend Ronnie Neel at Apex Hobbies said I could put it on a 40 sized plane with no problem, so I'm going to put it on an Ultra Stik 40 that I haven't finished yet. According to the instructions you have to let it rev, so I say, no problem, and Whyes, you are right about the fuel consumption, it went through 6 OZ. in short order. It is not loud though. Unfortunately the only 10x5 prop I had was an APC which I hate because you always have to grind most of one blade off to balance them. I'll run it some more tomorrow and keep you posted.