I really wasent planning on stuffing a .40 in it I just wanted to know if you could. So I shouldent look at anything over a .30? That sounds preaty good. I'm going to the hobby shop tonight and looking for an engine so I will see what I can come up with. If they dont have anything, A person on the fourms e-mailed me with on offer on a magnum .25 for 50 bucks. It was run on the bench and wasent even broke in. Are those good motors? Thanks