I have a vallyview 20cc it pulls a heavy great planes Super Chipmunk quite well. I also have a G-26 stock engine in a Hanger 9 Super Cub.
The 20cc is very close to the 26cc. The 20cc is running a 15/8 . The 26 a 18/6.
The 20cc also have reed valves in them. Something zenoah has not fooled with. Yes I know Walboro carbs have a reed
The G-26 is also 10 years old. Runs like a clock.
Now a option I never tried. I am a boat guy. Zenoah has that market. I am running a 30cc head with a stoker 1mm crank Mod head in a Gas Sport Hydro. These boats are super fast. Tuned pipes are also used.
So why not a airplane ?
anyone interested visit www.gizmomotors.com