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The University of Idaho's entry into the 2006 SAE Clean Snowmobile Challenge (CSC) was a second-generation gasoline direct-injection (GDI) two-stroke powered snowmobile. A modulated and battery-less direct-injection system was used to decrease exhaust emissions and improve fuel economy without reducing the power output of the engine. The team added a reduction catalyst designed for a two-stroke to the exhaust silencer to further reduce exhaust emissions and noise. Under-hood noise was targeted by using sound absorbing materials and a sealed hood. Chassis noise was addressed by using a spray-on rubberized material that absorbs vibrations transferred through the chassis. The snowmobile entered into the 2006 SAE CSC competition was lightweight, easy-to-ride, powerful, fuel efficient, and had reduced exhaust emissions.

The University of Idaho's (UI's) entry into the 2007 SAE Clean Snowmobile Challenge (CSC) was a third-generation gasoline direct-injection (GDI) two-stroke powered snowmobile. The modulated and battery-less direct-injection system fully met the competition goals of “improved emissions and noise while maintaining or improving the performance characteristics of the original snowmobile.” The students designed and manufactured a new head for a stock two-stroke 600cc snowmobile engine. The head was designed to use direct fuel injection to control fuel quantity and timing to reduce fuel short-circuiting. Performance was refined through the use of precise engine mapping. The emissions output was further reduced by a reduction catalyst located in the exhaust silencer. Noise from the engine compartment was reduced by using sound absorbing materials and a sealed hood. The UICSC team consisted of students from freshmen through graduate students.

Gasoline direct injection (GDI) two-stroke engine technology has been developed for use in snowmobile applications. Applying GDI to a two-stroke engine significantly reduces emissions of unburned hydrocarbons and improves fuel economy by reducing the short circuiting of fuel that occurs in conventional carbureted two-stroke engines. The GDI design allows for two different modes of combustion, stratified and homogeneous. Stratified combustion is typically used during idle and light to moderate loads at low engine speeds while homogeneous combustion is used at moderate to high loads and medium to high engine speeds. This work presents the process and results of determining which mode of combustion provides better fuel economy during cruise point operation, and where the transition from stratified to homogeneous combustion should occur in snowmobile operation.