Honda BF250 Engine - Design Attributes

1. Discuss the design of the new Honda Marine BF250 engine. How does the styling concept of the engine relate to enhanced performance?

The Honda Marine BF250 four-stroke engine is the newest and most powerful outboard to join the Honda Marine lineup and now becomes the company's flagship model. The design of the BF250 incorporates a number of advanced, technological innovations that contribute to the engine's high fuel economy and excellent performance.

The all-new Honda 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 styling concept of the Honda BF250 is a departure from other Honda Marine outboards in that the aesthetic design is sleeker and slimmer. In addition, the cowling of the new BF250 exhibits a sharper, more angular profile over previously introduced models. The overall design is streamlined and more aerodynamic, with chrome lines conveying power and speed.

The marine direct air dual circuit induction system on the new Honda BF250 engine is discussed in greater detail in the Power & Performance section of this press kit.

2. What other design attributes enhance the operation and performance of the new Honda BF250 engine?

The new Honda BF250 engine is NMEA 2000® certified. NMEA 2000 is a combined electrical and data specification for a marine data network for communication between marine electronic devices such as depth finders, nautical chart plotters, navigation instruments, engines, tank level sensors and GPS receivers. Parameters of this certification are defined and controlled by the U.S.-based National Marine Electronics Association (NMEA). This accreditation signifies that a product has been tested to meet specific critical safety criteria and to correctly implement network management and messaging. In meeting this certification, the Honda BF250 does not require the added expense of proprietary gateway devices; the certification also correlates with enhanced safety as the new BF250 engine is equipped with engine oil pressure and overheat information alerts.

The design of the Honda BF250 incorporates a spark plug maintenance cover which assists in ease-of-maintenance of the spark plug. This window provides access to the spark plugs without removing the entire engine cover. The engine also includes a high-quality, cost-effective nickel spark plug that seals the combustion chamber.

Because the BF250 engine mounts on industry-standard 26" centers, repowering twin BF250s is convenient. Having a 26" industry-standard engine mount is an advantage in several ways. In terms of repowering, older boats traditionally utilized the standard 26" distance, making it an easy fit to repower with Honda engines that utilize the same standard. By extension, having to modify a transom to accommodate a different distance is costly. Having ample room between the two outboards allows for easier access for maintenance, and this distance provides tighter turning capability.

The technologically advanced Electronic Control Unit (ECU) in the Honda BF250 can predict the operator's shifting operation based on changes in engine speed and throttle position. In order to reduce the shifting load, the ECU actually controls the ignition timing to modify torque when the operator shifts from partial to neutral. The below diagram illustrates the benefit of this shifting load reduction control.