The new Honda Marine BF250 outboard engine boasts the best fuel economy level in its class. Discuss how second generation lean burn control contributes to increased fuel efficiency.
Lean Burn Control (incorporated in Honda marine engine models BF40, BF50, BF60, BF75, BF90, BF135, BF150, BF200, BF225, and BF250) automatically adjusts the air/fuel mix according to speed and load while maximizing power throughout the acceleration range - providing as much as 20 percent greater fuel economy in cruise mode (2,000 to 4,500 rpm). Concerning the new BF250 engine, this feature has been enhanced to improve fuel efficiency even further in specific cruising ranges, resulting in best-in-class fuel economy - 16 -30 percent better than competitive models, depending on specific running conditions. As the below diagram depicts, the lean burn control system accurately measures and monitors the fuel delivered to the engine's combustion chamber (under various loads and throughout the power band) and determines what the optimal air/fuel ratio should be for best fuel economy. Further, to burn the exact amount of one gallon of gasoline, approximately 14.7 gallons of air is required. The air/fuel ratio control is performed by the Electronic Control Unit (ECU), based on the feedback from the O2 sensor, allowing more accurate control in the lean-burn range.