Colorado State University mechanical engineering students are taking a tried, true and rather unusual approach to winning the Clean Snowmobile Challenge 2000 March 20-31 in Jackson, Wyo.
Sponsored by the Society of Automotive Engineers, teams of college students compete to design and build quieter snowmobiles that produce less pollution than current models.
The mostly-undergraduate team, led by Justin Mick, a graduate student and snowmobile enthusiast, has ignored a recent trend to use heavier, less-powerful four-stroke engines to offset the pollution and noise from the two-stroke engines used in current snowmobiles.
Instead, they’re sticking with the tried-and-true, 100-year-old two-stroke engine. It’s lightweight, powerful in relation to its size and a standard for snowmobiles. Those two-stroke engines, however, at one point have both intake and exhaust ports open at the same time, producing lots of noise and leaving as much as 35 percent of the air-fuel mixture in each cylinder unburned and spewed into the air. A typical snowmobile engine can produce as much hydrocarbon waste and carbon monoxide as 100 automobiles.
To reduce pollution, the Colorado State team has added fuel injection for precise fuel control, a supercharger to push out the old exhaust products and a catalytic converter to oxidize pollutants that escape the engine. The snowmobile also boasts a specially designed muffler, a new high-performance suspension and even an ergonomic seat. The hood is painted in Colorado State green and gold.
"There’s no single magic bullet (to noise and pollution issues), so we’re taking a very comprehensive approach," said Bryan Willson, associate professor of mechanical engineering and team adviser. "Over the past five years, we’ve developed a lot of technology at Colorado State to clean up two-stroke engines, but we’ve never applied it to snowmobiles."
The effort has required a surprising level of engineering acumen and ingenuity, Willson said. "Students have to stitch together a lot of technology."
Mick, a master’s candidate in mechanical engineering, has been snowmobiling since he was three. He appreciates the power and lightness of two-stroke engines, but like other snowmobilers, he’s heard criticisms from park and public lands officials, other backcountry recreationists and environmentalists. So, finding a solution is important to him.
Some teams reportedly are installing four-cycle engines similar to those that power automobiles. Although quieter and less polluting, four-cycle engines have disadvantages for snowmobiles: they’re less powerful, have poorer acceleration and, because of their greater weight, can bog snowmobiles down in deep powder.
Mick, who led some members of the team on their first snowmobile ride this winter, has been working with other team members on design concepts for about a year. They’ve had to solicit contributions and invent new test devices for innovations such as the fuel injectors. Team members put in long hours, moving from one task to another while waiting for a machined or off-the-shelf part to arrive. Nonetheless, with deadlines looming, Mick thinks the team is onto something the industry will note.
"Some of our team members have taken it to heart and are highly motivated," he said. "If we don’t win, some of us are going to be very disappointed."
Each team receives a snowmobile to work on, donated by the Society of Automotive Engineers. While snowmobile manufacturers aren’t involved in the Clean Snowmobile Challenge 2000, industry observers are expected to be on hand. The Colorado Snowmobile Association and a number of individual clubs have been benefactors of the Colorado State effort.
Based on design proposals, Colorado State was one of only six teams invited to participate in the 2000 competition. Entries will be judged on noise and exhaust emissions, acceleration, hill climbing ability and technical presentation.
Mechanical engineering majors in the College of Engineering are required to undertake a senior design project in their last year. The choice of projects include projects include a race car, a human-powered vehicle and a walking machine; this year is the first for snowmobiles. The senior experience is well worth the effort the students put into it, Willson said.
"One thing we’ve found in the process of requiring every student to undertake a project is that the quality of the educational experience for the students becomes very high," he said. "What they work on are real-world engineering challenges."