We came across some interesting information about riding sleds in the mountains. We’ve mentioned several times over the past few years that sleds lose horsepower as they gain elevation—generally 3-3.5 percent of their horsepower for every 1,000 feet you go above sea level. For example, if your sled cranks out 100 horsepower at sea level (0 feet), the horsepower will drop to 65 at 10,000 feet—a 35 percent drop.
The information we came across addresses emissions as you gain elevation. The information comes from the article, "The Snowmobile Dilemma," by Howard Haines, who works for the Montana Department of Environmental Quality. The basic gist of the article is how certain fuels and oils can reduce the emissions of a snowmobile with special references to Yellowstone National Park.
The part that caught our eye though, states, "Like everything else, users need to follow the manufacturers’ recommended setup for fuel, temperature and elevation for overall performance and safety of snowmobiling. Observations in West Yellowstone showed that a number of snowmobile users operated machines not properly set up for Yellowstone-area elevation. The typical increase in elevation of 1,000 feet along a Yellowstone area trail will make the fuel mix richer due to less oxygen in a set volume of air and might cause the machine to operate poorly and produce more emissions.
"To verify this observation, the Southwest Research Institute also ran a laboratory test on an engine not adjusted for elevation to simulate the effects of increased elevation on emissions and performance. The test showed that hydrocarbons increased by 31 percent, carbon monoxide increased by 14 percent, particulate matter increased by 27 percent and fuel consumption