A traditional Wankel engine has a rotary block in the shape of a reuleaux triangle moving in a more cylindrical stationary chamber. The "inside out" refers to h

A traditional Wankel engine has a rotary block in the shape of a reuleaux triangle moving in a more cylindrical stationary chamber. The "inside out" refers to how this engine is a more cylindrical rotary block moving inside a stationary reuleaux triangle chamber.