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 ...

In the early days of engine building, a pre-Wankel rotary engine powered thousands of aircraft. One of several problems: It spewed castor oil on its pilots.

There are a lot of strange automotive designs out there, but this defunct engine from the '70s may just be the weirdest one ...