ORIGINAL: ckoerner
Think it would be possible to put a JET FIRE .50 on it? I just don't know how well the pipe would mount.
You can do it, with a bit of tweeking. You are not racing, so mods to the fuselage are ok, and engine mounting is just generic.
Since the pipe somewhat heavy and is more aft, you can mount the engine forward a bit (longer mount rails or a spacer behind the mount) that will help you clear the header/firewall issue. You should be able to hit the CG set up like this. Backplate mount is probably not going to work without some customizing of the firewall.
Rudeboy's photos help a lot with visualizing this.
You may have to mount the engine a bit more than 90deg to the side- to get the pipe to clear the bottom of the wing. In that case, install some 1/2" triangle stock up inside the bottom of the fuel tank area behind the firewall, and you can sand-away some of the lower corner of the fuselage and firewall if needed to clear the header (no 1/4" radius to worry about). Worry not about tank placement after adding the wood inside and making the compartment smaller. If you use a bubble tank, you can install that where ever it fits
Do not run the engine upright if you can avoid it. Installation may be easier, but fuel draw uphill about 1.3" that way - bad idea. Inverted is ok, but sorta the same fuel height issue - just upside down (flooding on the ground) and we all know that nose-over is going to happen - nothing like cylinder fins full of dirt.
Somewhere in my files at home I have a photo of an old scat-cat that was built with a round backplate, and a FIRE .46 engine some years ago. The front end of the plane was customized to conform to the 2" round backplate. Looked kinda nice.