An innovative new combustion engine eliminates half the guts of a traditional engine, and uses a fascinating internally-rotating piston and sleeve arrangement, making it lighter, simpler and more efficient while still making strong power and torque. Michael Arsenaeu designed the Avadi engine 20 years ago in the hopes of creating an entirely new engine design to be efficient as well as reduce emissions. In 2015, Avadi began the build and development. Rotary might be a good name for this sort of engine, if the name wasn't already taken. Everything inside the crankcase rotates, but unlike a Wankel-style rotary engine, this...