Design and Validation of the 2015 University of Idaho Clean Snowmobile Challenge Entry, Featuring a Dual Mode 797cc Two-Stroke Direct-Injection Engine with Active Noise Cancelation

The University of Idaho’s entry into the 2015 SAE Clean Snowmobile Challenge is a 2014 Ski-Doo MXZ-TNT chassis with a reduced-speed 797 cc direct injected two-stroke engine, modified for flex fuel use with blended isobutanol/gasoline fuel. A battery-less direct injection system was used to improve fuel economy and decrease emissions while maintaining a high power-to-weight ratio. Noise was reduced by operating the engine at a lower speed, reducing the throttle opening via an electronic throttle control, a mechanically active quarter-wave resonator, and by strategically placing sound absorbing/deadening materials throughout the chassis. A muffler was modified to incorporate a three-way catalyst, which reduces engine emissions without significantly reducing power or increasing sound output. The 2015 configuration implements a fuel economy switch which creates a powerful “sport” and an efficient “eco” mode. Pre-competition testing had the snowmobile entering the 2015 SAE CSC weighing 265 kg (585 lb) wet and achieving 10.2 l/100km (23 mpg) in mountainous terrain. The snowmobile had an EPA five mode emissions test score of 204 and 199, in eco and sport-mode respectively. Additionally, a J192 sound magnitude score of 73.5 dBA was measured under wet and heavy snow conditions in eco-mode.