Andrew Coholic, of Canada, designed and built this tiny 2-cycle radial engine by mounting three Cox .049 engines into a common crankcase. The engines are geared together with a common propeller shaft, and they alternately fire every 120 degrees. The carburetor is mounted to a manifold that feeds fuel to each engine upon its intake cycle.

Two-cycle engines usually require pressure in the crankcase to force fuel into the combustion chamber on the intake cycle. The gearing of individual 2-cycle engine together eliminates the need for a pressurized crankcase. Finished in 1999, this engine is 8”-long, 4”-wide, and 9”-high.

A single-cylinder, two-cycle engine produces the necessary pressure as the piston is driven down toward the crankcase from combustion. Since radial engines have pistons traveling away from the crankcase at the same time other pistons travel towards the crankcase, the pressure is cancelled. Therefore, two-cycle radial engines require a pump or supercharger to increase and maintain pressure in the crankcase during operation.

Exhibit added: July 1, 2008 - Last modified: March 15, 2023

Presented by The Joe Martin Foundation for Exceptional Craftsmanship