Snow Dogs ready to ride
The Kettering SAE Clean Snowmobile team has re-engineered their Polaris sled to run lean, look mean and burn green.
They have been sleeping on the floor of the test cell and using doughnuts and energy drinks as a staple diet. But sugar isn't the reason the Kettering Snow Dogs are revved up for the seventh annual Society of Automotive Engineers Clean Snowmobile Challenge March 13 to 18 at the Keweenaw Research Center of Michigan Technological University (MTU) in Houghton, Michigan. They think they've got a "highly competitive" sled.
The Snow Dogs are competing against 15 other student teams from universities in the U.S. and Canada to during the six-day event, with snowmobiles re-designed to "Beat the Standards." The standards are the federal emissions standards that go into effect in 2012. Each team has modified their stock sled to reduce noise and emissions levels.
Clean Snowmobile ChallengeTM is an intercollegiate engineering design competition that challenges engineering students to re-engineer an existing snowmobile for improved emissions and noise while maintaining or improving the performance characteristics of the original snowmobile. The modified snowmobiles are also expected to be cost-effective.
The Kettering team is excited about their machine, a re-engineered Polaris FST Switchback. "We started from scratch this year," said team co-captain Chad Swartz, of Standish, Mich., "our main design strategy was to optimize emissions by incorporating ethanol E85 (a bio-fuel) and a fuel injector and two catalytic converters," he said.
"We have been working with Bosch to fine tune the fueling," said Swartz, "because we're using an injection pulse width system." The system, developed by Bosch, changes the amount of fuel introduced into the engine depending on a number of variables including engine speed and outside temperature. The catalytic converters were used in a series tohelp reduce emissions even further.
"Only a few teams are using ethanol," said Swartz, "this year the testing process includes a corrections factor that allows for the differences produced by ethanol versus gas." It takes into account the stoichiometric ratio (energy density) of ethanol, which requires more volume than gas over the same distance. It was because of the change this year allowing the correction for ethanol, that the team decided to use the bio-fuel.
"We've wanted to use it in the past because it provides a cleaner burn," said Swartz, "but we would have been sacrificing points for fuel efficiency against gas burners." The team has been able to pre-test their re-designed engine on the emissions test bench at Kettering.
Other changes they made to their stock engine were directed at noise reduction. The team built two custom absorption-style mufflers (glass pack mufflers) using calculations based on engine output noise and frequency.
Despite the time crunch that always occurs as the competition looms closer, the team felt a little extra pressure due to the fact they built their sled in three months because they recycled nothing from last year's sled and didn't receive their stock sled until January.
"There has been no option but to put on the push," said Swartz, some of us have been sleeping here to get everything done on time. Mechanically we're done, cosmetically we still have some things to do." The Kettering team is competing during the week prior to finals for the winter term. Their big push weeks have been divided between trying to prepare early for finals and get the sled ready for competition.
"It's tough if you have to take 20 credits plus do this," said Jason Sanger, of Ankeny, Iowa, co-captain with Swartz. The two joined the Clean Snowmobile team at Kettering in January 2005 and became co-captains when the leadership of team graduated. "But it shows future employers that you can do anything. Next year we'll have this year's sled to work with, giving us a whole year to test," Sanger added.
This year testing at the competition has changed for both traditional and zero-emissions entries. In the past, a control sled was used when ranking entries. Team members must now pass an objective noise test to get half of the points. After a passing grade, the rest of the points are then earned as recordings of the sleds are played to individuals and rated according to appeal. "That's how it's done in industry, first you pass the test and then you sell your sled," said Jay Meldrum, director of the Keweenaw Research Center.
This year for the first time, the zero-emissions sleds compete in a separate class. Due to differences in speed and distance abilities, the electric sleds are put to different tests then fuel-powered sleds.
Written by Dawn Hibbard