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Diesel engine NOx emissions requirements have become increasingly stringent over the past two decades. Engine manufacturers have shown through the use of EGR and SCR technology that these requirements can be met. However, the desires for improved fuel efficiency, lower overall cost, and potential legislation to reduce NOx levels further increase the demand for higher DEF dosing rates. To meet this demand, a new DEF mixing technology has been developed. This paper describes the development methods used to create a compact, in-pipe mixer which utilizes an optimized wire mesh along with swirling flow to permit high DEF dosing rates without deposit formation. Its excellent mixing characteristics allowed for high NOx reduction to be achieved. Utilization of this technology makes it possible to reduce regeneration frequency, reduce the overall size of the SCR system, possibly eliminate the EGR system, and improve fuel efficiency through combustion enhancements.

This paper discusses the Minnesota State University, Mankato Automotive Engineering Technology program's entry to the 2002 Clean Snowmobile Challenge. Included in this report are the snowmobile model chosen for modification, engine choice, modifications applied, methods used, and modification results affecting performance, emission control, noise reduction, production cost, durability, fuel efficiency, safety, and rider comfort. The MSU Mavericks devoted their main focus for the Clean Snowmobile Challenge 2002 to the comparison of a two-stroke cycle engine to a four-stroke cycle engine. A direct fuel-injected two-stroke cycle engine and a turbo-charged four-stroke cycle engine were selected and were subjected to extensive modifications and testing procedures. Each engine was tested for emissions, noise, and performance; these test results were used to determine the final entry design.