Jon,

I quite like the piped 32 SX's too but they are quite heavy. The OS AX series are veritable porkers weighing close to twice as much as a Webra of equal displacement. Weight aside, the 25/35 AX just don't bode well on classics. They are designed to turn lower pitch larger diameter props at lower RPM. That's where their power band is developed.

I think a lighter engine turning higher rpm's might do better on a New Era III which Jim has in mind to build. The piped 32 SX is great on slightly larger birds like Aurora's, Cosmos' and Mystics.

Jim, if you'd like to try an engine that will fly over 15 min on 4 oz of fuel, look no further than the Norvel. Comes with a muffler too and is current production. Very simple and nicely made. If you put a Macs 3.5 cc muffled pipe on it, the NE will go ballistic!

David