You mean dummy engine like the PT-17 version of this plane has?

You can buy the PT-17 dummy engine as a replacement part from Tower Hobbies. You'd also need the PT-17 cowl for mounting the dummy onto, which they also have.

I think the dummy engine that comes with the PT-17 looks hideous, so I did up a Williams Bros. 7 cylinder dummy for my GP PT-17. Since I'm doing mine as an electric, it doesn't have to get hacked up to make a glow engine fit inside it.

Rick