The Jupiter 220 2-cylinder opposed model airplane engine was manufactured by Farger & Joosten, Germany, in early 1980s. The engine is 9”-long, 11”-wide, and 6”-high.
These belt-driven, overhead camshaft engines (that also were available in a 1-cylinder version) are superbly engineered but quite heavy, so not practical for competitive flying. Despite the 37 cc capacity, the power output was considered low. The power could be increased with re-profiled camshafts, different plugs and added piston rings. (To re-profile means to machine a different shape to the cams to change when the intake and exhaust valves open and close.) This drastically affects the engine’s performance.
Unlike its competitors, the Jupiter was entirely machined from bar tock and no castings were used. The lack of performance and added expense of machining from ingot probably created the lack of sales.