6 ms·

Yes, BMW is known for a similar design: https://en.wikipedia.org/wiki/Flat_twin_engine https://en.wikipedia.org/wiki/Flat_twin_engine

digdugdirk 11y ago
Not quite. The engine discussed in this article is almost the reverse of BMW's engine design. The crankshafts (where the rotational movement is transferred to the gear box) would be where the heads of the BMW engine are located. This means the explosion causing the rotational movement is at the centre of the engine, and keeps heat loss to a minimum. That's partly how they're going to get such high efficiency out of this design. The other way is the (I'm guessing) massive compression ratio they'll need to achieve for the auto-ignition of gasoline to occur.
- hvidgaard 11y ago
  What I think, and this is without being ICE engineer, is the same effect that helps Mazdas SkyActive engines achieve high efficiency, higher compression and longer exhaust cycle. That a two stroke achieves a high power output is not surprising, and is one of the main reason they're used, as the power to weight ratio is superior to 4 stoke.
  - Grishnakh 11y ago
    To add to your comment, the SkyActiv engines are Atkinson-cycle engines, which improves efficiency by holding the intake valve during the beginning of the compression stroke, so that the exhaust compression ratio is greater than the intake compression ratio, extracting more work out of the exhaust gases. The disadvantage of this is that the engine has lower power density (it won't get the same HP/liter ratings that a similar Otto-cycle engine will). This can be made up for by adding an electric motor to make it a hybrid car, or by adding a supercharger (which makes it a Miller cycle engine). 2 strokes are terrible engines generally, because they have very high emissions, usually because they release unburned fuel in the exhaust.

6 ms·

Yes, BMW is known for a similar design: https://en.wikipedia.org/wiki/Flat_twin_engine https://en.wikipedia.org/wiki/Flat_twin_engine

by vmorgulis 11y ago

digdugdirk 11y ago
Not quite. The engine discussed in this article is almost the reverse of BMW's engine design. The crankshafts (where the rotational movement is transferred to the gear box) would be where the heads of the BMW engine are located. This means the explosion causing the rotational movement is at the centre of the engine, and keeps heat loss to a minimum. That's partly how they're going to get such high efficiency out of this design. The other way is the (I'm guessing) massive compression ratio they'll need to achieve for the auto-ignition of gasoline to occur.
- hvidgaard 11y ago
  What I think, and this is without being ICE engineer, is the same effect that helps Mazdas SkyActive engines achieve high efficiency, higher compression and longer exhaust cycle. That a two stroke achieves a high power output is not surprising, and is one of the main reason they're used, as the power to weight ratio is superior to 4 stoke.
  - Grishnakh 11y ago
    To add to your comment, the SkyActiv engines are Atkinson-cycle engines, which improves efficiency by holding the intake valve during the beginning of the compression stroke, so that the exhaust compression ratio is greater than the intake compression ratio, extracting more work out of the exhaust gases. The disadvantage of this is that the engine has lower power density (it won't get the same HP/liter ratings that a similar Otto-cycle engine will). This can be made up for by adding an electric motor to make it a hybrid car, or by adding a supercharger (which makes it a Miller cycle engine). 2 strokes are terrible engines generally, because they have very high emissions, usually because they release unburned fuel in the exhaust.