Among the numerous Stirling cycle engines that Al Vassallo designed and built is this large V-4 workhorse that he attached to a small generator and water pump. (Courtesy of Cherise Vassallo, Ingrid Vassallo, Andre Vassallo). Completed in 1994, the engine operates on propane gas that is delivered to special custom-built burners designed to direct as much heat to the heads as possible. Then the pump circulates water to cool the cylinders, which increases the power output and efficiency. It isn’t known if Al had a purpose for this engine, or if he was just experimenting, but he displayed and demonstrated its function at several of the local model engine shows and meetings. The engine is 13″-long, 16″-wide, 11″-high, and weighs 20 lbs.