When Mazda discontinued the RX-8, most people assumed the rotary engine was finished. The RX-8 was the last production car to use Mazda's signature Wankel rotary, and its departure seemed to signal ...

The internal combustion engine, for all its mechanical sophistication, still runs on a 19th-century mechanical idea: pistons rising and falling, a crankshaft spinning, a steam-age architecture ...

Wankel rotary engine powered thousands of aircraft. One of several problems: It spewed castor oil on its pilots.

While modern engines feature many tweaks and improvements on the original ideas, they usually aren't as interesting as the strange contraptions engineers experimented with in the early days. Take, for ...