Chris,

Yes, I used the OS 50SX and the Perry Pump on the second plane. I don't have any experience with conventional four strokes and didn't want to start. Also they are more expensive. I wonder how the RCV 58 four stroke would work on this plane. It doesn't have any valves.

I have a RCV 60 for SIG miniplane I am building. It is probably too much engine.

Anyway, if you place the OS engine on its side the fuel has to go two inches vertical to get to the carb. I figured it just wouldn't draw. In hindsight, a better choice would have to mounted the engine inverted.

I decided on the pump for the utmost in reliable fuel flow. I am considering trying to compete in the beginning class of IMAC.

The OS 50 SX has plenty of torque. If you are heavy handed on the throttle at low speed it will roll on you. I use a 11.5 x 6 prop. I have good acceleration and very near unlimited vertical.

Decisions, Decisions, have fun with yours...