I'm running a ys91fz in mine and it will put out of a hover pretty decently. Anything less (four stroke wise) will probably be very marginal. I haven't payed too much attention to how the 2 stroke guys are doing so I can't help you much there. I'm sure one of them will chime in. There's a huge thread around here on the UCD, but you'll probably spend half the day looking through it. GOOD READING THOUGH.