Niether the FX or the webra will fit completly inclosed although the webra would with a 1/2" prop spacer. I had one HE-100 with a K&B 3.5 in it and it was fully cowled with the pipe exiting just in front of the canopy. As for the prop on the webra I was using an 8x6
MA scimitar with 30% magnum fuel.