Students Build a Quiet Snowmachine
Jason Rohwer of Fairbanks likes the gritty, oily smell of snowmachine exhaust, and he loves the roar of his machine when he's out in the mountains. He also realizes that these sensations, which stir good memories of sunny days outdoors with his family, drive other people crazy. That's one of the reasons why Rohwer, along with fellow engineering student Edwin Dale Hahn, is trying to build a better snowmachine.
Rohwer, 22, and Hahn, 23, both seniors at the University of Alaska Fairbanks, recently returned from the Society of Automotive Engineers Clean Snowmobile Challenge, held in Jackson, Wyoming. Though they didn't come home with medals, Hahn and Rohwer are doing their part to continue the evolution of the snowmachine.
In the contest, students from 15 schools created models designed to be less stinky, less noisy, and less thirsty than conventional snowmachines. Contestants were asked to shoot their machines up mountainsides to compare performance, gun their throttles past a microphone to test decibel levels, and drive 100 miles while averaging 45 miles per hour to see who burned the least fuel. They also turned their machines over to professional drivers, who rated the handling performance. In the end, a team from the University of Waterloo in Ontario finished with the highest score. The UAF team of Hahn and Rohwer finished ninth despite shipping problems that caused their 1998 Arctic Cat Powder Extreme to miss the emissions testing event.
At their best, the students in the contest designed machines that exhaled two percent of the noxious gases of a standard "control" snowmachine. Their machines averaged 20 miles per gallon on a soft track, which was five miles per gallon better than the control machine. The best student exhaust systems muffled up to 75 percent of the noise. "When they were idling, you couldn't tell the machines were running," Hahn said, adding that the UAF team had the second-quietest snowmachine.
Hahn and Rohwer modified a car engine for their entry, using the same engine block that is under the hood of a Geo Metro. They chose a four-stroke engine instead of the conventional two-stroke engine beneath the cowling of almost every snowmachine in use. Though powerful and light, two-stroke engines spit out as much as 40 percent of their unburned fuel-and-oil mixture in their exhaust, Hahn said. Four-stroke engines use a system of intake and exhaust valves that close when the pistons fire, which prevents unburned fuel from escaping with exhaust gases.
The Environmental Protection Agency is proposing emission standards for snowmachines that might take effect by September, 2002. Snowmachine manufacturers are now producing a few four-stroke models, but the light and powerful two-strokes will be hard to replace. "The biggest challenge is finding out the best way to make compromises," said Chris Wright, an emissions engineer for Arctic Cat in Thief River Falls, Minnesota. "You have to figure out how to satisfy the customer's demand for power and handling and make progress on emissions and noise at the same time."
Hahn and Rohwer developed their clean machine as an after-school project. Two of their major modifications were turbocharging the 4-stroke engine for more power, and redesigning the oil pan so the larger engine would fit under a conventional hood. "One of our goals was to keep it looking like a snowmobile," Hahn said. "Some of the other entries looked like tractors," Rohwer said.
Wright, the Arctic Cat engineer, attended the competition in Wyoming as a judge and an industry sponsor. He said the students don't have the real-world constraints of making the machines attractive or durable, but the industry is getting some good ideas from the student designs. Though a clean, lightweight snowmachine with power is still a thing of the future, the future might not be that far off with the impending EPA regulations and the contributions of young riders who also happen to be engineers. "People get the idea that a sled can't be fast and clean," Hahn said. "That's simply not true."
