Well, there are engines that run "backwards" (clockwise), and there are crankshafts that you can pop into a stock engine to make it run backwards (at full power), and there are simple changes to the intake porting that a sharp person with a dremel can do himself (and can probably even figure out how to do himself... think about it) to make an engine run backwards at full power.

And If I bought an engine with a prop, I would the prop to match the engine, so I wouldn't be too surprised if a backward engine came with a pusher prop.

... But that's a lot of IFs.

Steve-o... That's a mystery to me... I've always recognized an engine running backwards by the wash blowing the wrong way and by it not being able to come oup to power. When it's running backwards with a "normal" (tractor type) prop and still thrusting forward and spools up to flying power, what about it tells you that it IS running backwards?