I have a Black Horse SU31 which is the same as the Phoenix SU31. I had it with a TT61 and its a waste of time, I used to have one with a TT46 which gave me limited vertical. The TT61 gave me more vertical but the wing loading went sky high. The TT61 was 10 oz more than the TT46 ... then I needed 2.5 oz on the tail to balance her out. All in all its about 13-14 oz more. All that to throw a 12x8 prop only? Landing had to be about 5-7 mph faster if not she will stall, also she will not float in like she used to on a 46 2C.

For more enjoyment go with the Magnum 52. Oh yes ... with a TT61 there is NO unlimted vertical. I think the best engine is a Saito 82.