Re: "Cross-Flow" vs "Looper" What's the difference and which
Re: "Cross-Flow" vs "Looper" What's the difference and which
The looper is a more modern design. Just about all 2strokes (motorcycles, chainsaws, etc.) are loopers now. Crossflow motors have a big deflector on the piston top which pushes the incoming fuel/air towards the top of the cylinder, so that it doesn't just go out the exhaust port. Loopers (Schnurle loop) achieve the same effect by more sophisticated methods - they aim the intake ports, etc.. <br /><br />I belive I am correct in saying that OMC loopers are more efficient and powerful (per cubic inch) than the crossflows. However, since the crossflow designs are older, OMC's had more experience with them & they typically are simpler and MAYBE based on both factors, more reliable. It is true that the commercial engines tend to be crossflows.<br /><br />Big outboards are unusual two-strokes in that there's the requirement for trolling - which means they have to produce tractable very low end power. I'm not sure how the manufacturers do that with a looper. Loopers count on gas momentum to get the flows going the way they want, and the momentum's very much lower at trolling speed. It would make sense that a crossflow might be a better 'broad powerband' motor (in theory).
