In 1994, Cliff Bumpus designed and machined this miniature engine from bar stock (aluminum ingots). The cylinders are spaced 120° apart in a circular pattern, typical for a 3-cyinder radial configuration. The miniature runs on glow plugs rather than spark plugs. The combustion of the fuel in the engine keeps the glow plug hot between cycles, so it does not need to be regulated or powered while the engine is running like a spark plug would. The engine is 7”-long, 11”-wide, and 10”-high.
The methyl alcohol fuel is mixed with castor oil which lubricates the internal engine parts. Since castor oil is not flammable, lubrication can occur before or after combustion, depending on the design of the engine. In either case, the excess castor oil is discharged from the engine during operation.