Just getting back into this sport (hobby?) after 30+ years. Back then everything was a kit and one I built was the UGLY STICK. Hated it from the start because it wasn't a "real" airplane. My planes don't have to be exact scale but must look somewhat like the real thing. The Elder 40 was never a real airplane but does look close enough to something they may have (should have?) built back then. The plans call for a .56 four stroke but it's been my observation that this reccomendations are alway under powered. I picked up a Saito FA72 for a good price and will use it. Don't have to be full throttle all the time. From reading the reviews it is just a slow Sunday flyer and a Chevy big block would not get more speed out of it.</p>