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Two stroke engines are actually smaller, cheaper, and more powerful than four stroke engines of equal displacement. The issue with two stroke engines is cleanli
by digdugdirk 13y ago
Two stroke engines are actually smaller, cheaper, and more powerful than four stroke engines of equal displacement. The issue with two stroke engines is cleanliness. Because there isn't a spare cycle to push all the extra unburned particles out of the chamber and let only clean air/fuel into the chamber, there is some loss of power efficiency due to the attempted combusting of leftover particles. This is more than mitigated by having double the amount of power strokes per equivalent displacement. There's actually some really interesting design techniques that have been used to "coax" the waste particles out of the chamber, take a look at MotoGP technology circa early 2000's if you want to learn more.
- marvin 13y agoAll the two stroke engines I have used (light aviation) have been terribly unreliable and painful to maintain. Won't start, often fires just on one cylinder, stops randomly, leaks oil everywhere. Is this a "shitty design" problem rather than an inherent problem with two-stroke engines?
- digdugdirk 13y agoProbably a combo of both. You know how I said above that there are some cool design techniques to get the old waste gases out of the cylinder? Well those techniques only work over a very narrow band of RPMs, under very specific air/fuel ratios. Your problem is even worse because you're in an aviation setting. Your engines are experiencing very different air densities, and this is causing the air/fuel ratio to change drastically compared to what they've been tuned for. If they get too rich, they stall. Too lean, they explode. The leaky oil? Yeah, that's probably just a two stroke being a two stroke. Due to the design, they aren't "oiled" like a car, you instead shoot the oil in with the gasoline in the injection cycle, and it just kinda seeps in and around the engine. That's the main reason why they're dirty - both literally and environmentally.
- Gravityloss 13y agoDiesel engines have less problems when inlet air goes to the exhaust, since in a diesel, inlet air doesn't contain any fuel. A two stroke diesel has thus some synergistic advantages. A direct injection otto engine could also work very well as a two stroke.
- userbinator 13y agoA bit of a tangential point, but two-stroke diesels also sound really awesome. http://www.youtube.com/watch?v=C-oDw2iVcTk http://www.youtube.com/watch?v=C-oDw2iVcTk http://www.youtube.com/watch?v=eEKlhdj7eEM http://www.youtube.com/watch?v=eEKlhdj7eEM