[1] https://en.wikipedia.org/wiki/Inversive_geometry
edit: on second though this would probably be too simple to be true.
“ "If you recall the Wankel," says Schkolnik, "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. You can drive it to a high compression, just by making the chamber smaller. And because it's stationary, we can directly inject fuel where the Wankel could not. So those are the two key advantages of the diesel: high compression ratio and direct injection.”
I did some crude geometric measurement on the geometry based on the video and the chamber doesn't seem to have the shape of an Wankel rotor inverted with respect to a circle.