ORONO – For some, the sound of Maine in winter is the crackle of a fire or the rumble of plow trucks in the middle of the night. For many, however, it’s the loud, grating buzz of a snowmobile racing through the woods, much to the chagrin of homeowners who live near trails.

For 16 mechanical engineering students at the University of Maine, the deafening engine noise from snowmobiles is a thing of the past.

The Clean Snowmobile Challenge team, led by professors Michael Peterson and Charles Maguire, is part of an international competition to produce a snowmobile that is quieter, more energy-efficient and less polluting.

Approaching the team’s modified 2003 Arctic Cat while it is running, one hears only a low whir, no louder than a typical car. It’s amazingly quiet – so quiet that a bystander watching a demonstration of the vehicle on Friday couldn’t believe it was actually running.

The snowmobile was put through its paces on Friday at the Crosby Lab at the university.

According to Peterson, a mechanical engineering professor, the snowmobile runs 99 percent cleaner than regular snowmobiles.

“The [Environmental Protection Agency] has mandated that snowmobiles be cleaner and quieter,” Peterson said. “This machine is so quiet you can hear the skis. It’s really a dramatic difference. As long as it’s cost-effective, I don’t see any reason why all snowmobiles won’t be like this soon.”

This particular machine, purchased new in 2003 by the team with help from the UMaine College of Engineering and Applied Thermal Sciences Inc., is in its second year of modifications. The team has put nearly $12,000 worth of modifications into the snowmobile, though if those changes were to be made in mass production, they would raise the price of the $7,000 machine by only $400 to $500.

The team will head today to Michigan Tech in Houghton, Mich., to compete with schools from the United States and Canada to see whose snowmobile is the best. One part of the competition is a 100-mile endurance test. In last year’s event, the UMaine team made it through the test, while a third of the other schools experienced problems during the race and couldn’t finish.

Last year’s team came in third in the competition. Team captain Kate Charles explained the modifications done this year on the snowmobile.

“We installed a microcontroller into the engine that works with the catalytic converter we installed last year,” said Charles, a UMaine senior. “Snowmobiles don’t have catalytic converters, so they put off hydrocarbons and all kinds of stuff you don’t want. The converter combined with the microcontroller reduces emissions even more.”

Trevor Jenkins, a senior mechanical engineering major, worked on the hood of the machine, the section that most affects noise.

“On the inside [of the hood], we put sound dampening foam,” Jenkins said. “It’s about an inch or so thick, and it really reduces engine noise.”

Corey Hibbard, who worked on the engine and on electronics, said the modifications were a welcome transition from typical snowmobiles.

“It’s a good change,” Hibbard, a senior, said. “It’s not loud, and you don’t stink since the emissions are so reduced.”

For snowmobilers, the big question undoubtedly will be: How does it run?

“We got it up to 70 miles per hour once,” Peterson said. “It can’t quite get up to 100 like regular snowmobiles, but it’s not bad.”

Senior Steven Cook took the machine out on a test run on UMaine’s mall, which was covered with untouched snow from Wednesday’s storm. Cook zipped around in a circle a few times, gaining speed easily.

Charles then took it out for a spin, starting at the south end of the mall by Fogler Library and driving in a straight line all the way to the north side of the mall by the field house.

Cook, watching Charles, sounded envious.

“You could probably get some air on those snowbanks,” Cook said, meaning Charles could perform a jump with the machine.

Asked why she didn’t do it when she was out there, Charles shrugged.

“Believe me, I’d love to,” the student said. “I’d probably get in trouble, though. It’s for school.”