Background
Due in part to stringent air pollution control measures recently imposed on the outboard engines industries; BRP has developed the industry-leading E-Tec two-stroke direct injected outboard engine. While the E-Tec is a very clean engine that meets current CARB three star standards, BRP wants to further reduce engine emissions. The areas of focus for reducing emissions in this project are reducing amounts of hydrocarbons, maintaining/improving fuel economy, and making the design easy to package/manufacture. The current engine uses direct injection coupled with a unique tuning strategy as its two main sources for low emission output, however, the engine is not catalyzed.
Project Focus
Team COP will research and explore methods of reducing the unburnded hydrocarbon emissions of the E-Tec outboard engine. With the added goal of maintaining or improving stock fuel economy and performance. The scope of this project will include proof of concept of the methods discovered and developing a testing procedure to quantify/monitor the effects of the method.
Design Alternatives
Three broad design alternatives exsist; Engine Design, Catalyst,and Thermal Reactor. Engine Design was proven effective on the direct injection engine used by the University of Idaho Clean Snowmobile Team; however, Engine Design is outside of the scope of a senior design project. Catalysts are also proven technologies and are commonly used in the automotive industry. Catalysts proved a reactive surface which can facilitate the chemical combustion of the unburned fuel. Thermal Reactors have been extensively reasearched by the automotive industry as a lower cost emission control device. However Thermal Rectors were never used extensively because of the engine tuning changes required (fuel and timing). More fuel had to be added to facilitate the necissary exhaust temperatures. Thermal Reactors are simply a resonating/mixing volume downstream of the exhaust port. Typically Thermal Reactors also include a secondary air source, to provide the necissary oxygen for a reaction. However in a two stroke engine, there is a substantual amount of oxygen that exits the engine unused.
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