Today I learned about the
Duke Axial Engine, from
Duke Engines, down New Zealand way.
It's pretty wild.
The engine is so smooth, they start it, run it, rev it, and turn it off, all with a coin standing on edge on top of the engine, per video at the link....
They've run it as high as 14:1 compression ratio on 91 octane gasoline. That would usually require
a lot more octane.
I think those boys might be onto something.