This is kind of vaguely similar to LiquidPiston's engine[1], which is sort of like a wankel engine turned inside out. (This has a couple benefits. The equival

This is kind of vaguely similar to LiquidPiston's engine[1], which is sort of like a wankel engine turned inside out. (This has a couple benefits. The equivalent of apex seals can be on the non-moving part of the engine and thus are easier to lubricate. Also, the combustion chamber can be made more closely to spherical, which in theory should improve efficiency and emissions quite a bit.) As of awhile ago, the LiquidPiston folks were working on improving longevity. Building a test engine that works is an impressive achievement, but getting it to last also requires a lot of careful engineering and testing. [1] https://news.ycombinator.com/item?id=25450477 https://news.ycombinator.com/item?id=25450477