ORIGINAL: aspeed

Over the years it has been proven that rear rotor motors are slower at higher revs at least. Toad, the AP .09 and .15 motors have a good simple design that has the bypass channels machined in the liner instead of the case. The .15 is machined all the way through to the piston. It wouldn't be too hard to make a case for something like that with a Picco or Norvel Piston/Cyl. The ball bearings would stop me from trying this. The Norvel case could be maybe epoxied up and a new exh. port machined in the back for a rear exh, although the Picco looks like a better liner design. As for Hobby King, maybe an exhaust at 45 degrees might be a good selling design. The OS has the liner at an angle and a side exh. That could easily be a rear exh. with a 45 degree exit, and then an adapter for rear or side.