The RCS engine will fit fine, but the expansion chamber of the Pitts muffler looks like it will be a non fit. The Fuse is 4 - 1/8" wide, and the cowl, just a tad bit wider.

THe RCS expansion chamber part of the pitts muffler is 4 - 1/8" and the side of the muffler that attaches to the engine is 2 - 1/4", so it requires more space on the port side and less on the other. This means that you would need more space than the FW3D cowl can give you, UNLESS...

You could cut and opening where the muffler contacts the cowl, (uggg...) to allow for some space. I believe the other side would be ok then.

You also have to be careful that the cowl does not come in contact with the muffler as the gasser is very hot and WILL melt the cowl if it touches it.

My guestimation is that the engine will fit easily, but the muffler will cause a problem without cutting.

Here's a link to the RCS site.

http://www.rcshowcase.com/RCS%20Engines.htm

Jim!