The New DF50AV is designed with a "High Energy Rotation" lower unit sporting a 2.42:1 gear ration, which enables this new model to use a bigger 14" propeller - perfect for powering pontoon boats and other large, heavy craft. This mid-range engine is also designed with Lean Burn Fuel Control System, which adjusts the air/fuel mixtrue according to operating conditions. The system significantly improves fuel efficiency across the operating range, from low speeds well up into the cruising range.