5 ms·

Wouldn’t this have the same problems as Wankel engines, that is suboptimal combustion due to the weird crescent-shaped combustion chambers?

mlyle 6y ago
Read the article. >..."they have a triangular rotor inside a peanut-shaped housing. We have the opposite, a peanut-shaped rotor in a tri-lobed housing. So take everything you know about the Wankel and turn it literally inside out. They have a long, skinny, moving combustion chamber, we have a stationary combustion chamber that's nice and round...
- deleted 6y ago
  [deleted]
- layoutIfNeeded 6y ago
  Can you point me to a timestamp where you see a “nice and round” combustion chamber in the video? I still see a crescent shaped one.
  - crote 6y ago
    Look at the red areas in this image: https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/5f6086e9bbbabd8f300f29a9_engine.png https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/5f6... Left is a Wankel engine, right is the LiquidPiston engine. The red areas on both sides are the combustion chambers during ignition. The chamber is clearly a lot rounder.
    - rocqua 6y ago
      The right picture, with that kind of chamber, seems like it would have pretty limited compression ratios
      - elihu 6y ago
        It does look like that, but it may simply have been drawn with those proportions for illustrative purposes. On the other hand, perhaps the diagram has correct proportions but they're misleading: the combustion area might be roughly spherical rather than cylindrical, and we're just seeing the cross section that shows its maximum area. edit: actually, this is covered in their FAQ: > What is the compression ratio? > For the X Mini 70 cc spark-ignited prototype, the compression ratio is 9:1. The diesel prototypes have operated at between 14:1 and 18:1, and should be able to go higher, to 25:1 or more.
  - phkahler 6y ago
    The crescent shape has poor efficiency because of the low volume to surface area ratio. A wankel has a similar issue but this looks worse to me.
    - fastball 6y ago
      The three small chambers are entirely sealed off from the main chamber during combustion, it is only crescent during intake/exhaust. https://www.liquidpiston.com/how-it-works https://www.liquidpiston.com/how-it-works

mlyle 6y ago

Read the article. >..."they have a triangular rotor inside a peanut-shaped housing. We have the opposite, a peanut-shaped rotor in a tri-lobed housing. So take everything you know about the Wankel and turn it literally inside out. They have a long, skinny, moving combustion chamber, we have a stationary combustion chamber that's nice and round...

deleted 6y ago
[deleted]
layoutIfNeeded 6y ago
Can you point me to a timestamp where you see a “nice and round” combustion chamber in the video? I still see a crescent shaped one.
- crote 6y ago
  Look at the red areas in this image: https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/5f6086e9bbbabd8f300f29a9_engine.png https://uploads-ssl.webflow.com/5f6086e9bbbabd41a20f2984/5f6... Left is a Wankel engine, right is the LiquidPiston engine. The red areas on both sides are the combustion chambers during ignition. The chamber is clearly a lot rounder.
  - rocqua 6y ago
    The right picture, with that kind of chamber, seems like it would have pretty limited compression ratios
    - elihu 6y ago
      It does look like that, but it may simply have been drawn with those proportions for illustrative purposes. On the other hand, perhaps the diagram has correct proportions but they're misleading: the combustion area might be roughly spherical rather than cylindrical, and we're just seeing the cross section that shows its maximum area. edit: actually, this is covered in their FAQ: > What is the compression ratio? > For the X Mini 70 cc spark-ignited prototype, the compression ratio is 9:1. The diesel prototypes have operated at between 14:1 and 18:1, and should be able to go higher, to 25:1 or more.
- phkahler 6y ago
  The crescent shape has poor efficiency because of the low volume to surface area ratio. A wankel has a similar issue but this looks worse to me.
  - fastball 6y ago
    The three small chambers are entirely sealed off from the main chamber during combustion, it is only crescent during intake/exhaust. https://www.liquidpiston.com/how-it-works https://www.liquidpiston.com/how-it-works