Discuss the features and advantages incorporated into the new Honda BF250 that enhance overall power and performance.
The superior performance, power, and reliability of the new Honda Marine BF250 engine are the result of several exclusive technological features. The Honda BF250 is a high-performance 3.6 L VTEC® (see below discussion) engine that incorporates technological advancements from both Honda's automotive and marine outboard engine lines. For example, when designing the BF250, Honda engineers increased the stroke of the existing Honda Odyssey car engine - expanding its displacement to 3.6 L. The result is a new outboard model with excellent performance, improved fuel economy, more power, and increased reliability.
Integrated into the BF250 design is Honda's Variable Valve Timing and Lift Electronic Control® (VTEC®). First debuted in the high-performance Acura NSX sports car, VTEC® technology also is featured in the designs of the Honda Marine BF225, BF150 and BF90 engines, providing all of these models with a unique blend of power, torque, and efficiency at any speed. VTEC® works to vary the lift and duration of the intake valve opening to deliver optimal performance at both low and high rpm, resulting in peak performance at all speeds. The technology provides a broad, flat torque curve and smooth power delivery throughout the engine's entire operating range, allowing the operator to enjoy both outstanding performance and impressive fuel economy.
The Honda BF250 engine incorporates the Boosted Low Speed Torque (BLAST™) System which dramatically improves holeshot acceleration by advancing ignition spark timing to within one degree of the knock limit during 'hammer down' acceleration. The Engine Control Module (ECM) then steps in to increase injector timing, creating a more potent air/fuel mixture. The resulting boost in available torque at low rpm contributes to a strong holeshot (off the line acceleration) to get the boat up on plane quickly. The ignition spark timing is appropriately adjusted under slower throttle advancement, ensuring a leaner air/fuel mix and improved fuel efficiency.
The BF250 engine incorporates the world's first marine direct air dual circuit induction system of its type on a production outboard. The first circuit draws air into the front and around critical engine components, and a top-mounted cooling fan draws cooling air over the alternator. The second circuit routes cool air from the upper intake vents, removes moisture, and then inducts it into the throttle body. This system provides for cooler, denser air for better combustion than conventional under-cowl induction systems.
The design of the variable air intake system on the Honda BF250 also includes a large air-intake silencer that reduces noise. The silencing effect results from a chamber being added to the intake passage - causing sound waves to interfere with one another - creating a side branch effect that quiets noise.