Development of an in-service snowmobile emission test procedure for the SAE clean snowmobile challenge

Document Type

Conference Proceeding

Publication Date



Department of Mechanical Engineering-Engineering Mechanics


As concerns over air pollution continue to increase, all vehicles are subject to greater scrutiny for their emissions levels. Snowmobiles and other off-road recreational vehicles are now required to meet emissions regulations enacted by the United States Environmental Protection Agency (EPA). Currently these vehicles are certified using a stationary test procedure with the engine operating attached to a dynamometer and following a five-mode test cycle. The five modes range from idle to wide open throttle and are chosen to represent the typical operation regime of a vehicle. In addition, the EPA five-mode stationary emissions test has been traditionally used for scoring competition snowmobiles at the SAE Clean Snowmobile Challenge (CSC). For the 2009 CSC, in-service emission testing was added to the competition to score the teams on actual, in-use emissions during operation of their competition snowmobile operated on a controlled test course. The testing was done using a Semtech-DS mobile emissions analyzer that was installed in an enclosed sleigh and pulled behind the snowmobile. This paper discusses the development of the in-service test procedure that was used to score the competition snowmobiles during the 2009 CSC and presents preliminary data collected during this development. The results from the In-Service Emission Event at the 2009 CSC are also presented and discussed along with the results from the stationary, five-mode emissions test. Future development plans for in-service emission measurements include improving accuracy and incorporating real-time fuel flow measurement to permit truly dynamic vehicle operation during emissions sampling.

Publisher's Statement

Copyright © 2009 SAE International. Publisher’s version of record: https://doi.org/10.4271/2009-01-2625

Publication Title

SAE Technical Papers