Snowmobile Vehicle

Most snowmobiles are still powered by two-stroke engines, although Alpina Snowmobiles and Yamaha have been using four-strokes respectively since 2002 and 2003. However, in the last decade several manufacturers have been successful in designing less polluting motors, and putting most of them in production. Yamaha and Arctic-Cat were the first to mass produce four-stroke models, which are significantly less polluting than the early two-stroke machines. Alpina offers a 4-stroke EFI engine equipped with a catalytic converter and state of the art dual oxygen-probe. Bombardier's E-Tec two-stroke motors emit 85 percent less pollutants than previous carburated 2-strokes. Polaris has developed a fuel-injection technology called "Cleanfire Injection" on their 2 strokes. The industry is also working on direct injected "clean two strokes" which are actually an improvement on carbureted four strokes in terms of NOX emissions.
Independent researchers are also working on the air pollution issue. Even undergraduate and graduate students are participating in contests to lessen the impact of emissions from snowmobiles. The Clean Snow Mobile Challenge is held yearly at Michigan Tech University regrouping the entries from universities from across United States and Canada. Some of the participants in recent years have been the École polytechnique de Montréal with a quasiturbine engine and students from École de technologie supérieure of the UQAM with a less polluting two-stroke engine using E85 and direct injection.
• Noise
Maximum noise restrictions have been enacted by law for both production snowmobiles and aftermarket components. For instance, in Quebec (Canada) noise levels have to be 78 decibels or less at 20 meters from a snowmobile path. Now in 2009, snowmobiles produce 90% less noise than in the 1960s. However, noise has cumulative effects on users and people living near those trails that are not well researched. It is still the origin of numerous complaints. Efforts in regard to noise reduction have now generally shifted to suppressing mechanical noise of the suspension components and tracks. Arctic Cat in 2005 introduced "Silent Track technology" on touring models such as the T660 Turbo, And Bearcat. Some M-Series sleds also had this. Ski-doo has since then also used comparative "silent track technology" on some production models.