RE: U-Can-Do 3D .46 Engine Question
I suggest a .91 Thunder Tiger, Magnum, or Saito. I think they are all good brands. I am running a Thunder Tiger .91 4-stroke on my UCD .46, and it delivers plenty of power. If you go with a .91, I recommend putting a 13X7 APC prop on it. That seems to pull mine around great.
--Garret H