Development and Validation of a Snowmobile Engine Emission Test Procedure

An appropriate test procedure, based on a duty cycle representative of real in-use operation, is an essential tool for characterizing engine emissions. A study has been performed to develop and validate a snowmobile engine test procedure for measurement of exhaust emissions Real-time operating data collected from four instrumented snowmobiles were combined into a composite database for analysis and formulation of a snowmobile engine duty cycle. One snowmobile from each of four manufacturers (Arctic Cat, Polaris, Ski-Doo, and Yamaha) was included in the data collection process. Snowmobiles were driven over various on- and off-trail segments representing five driving styles: aggressive (trail), moderate (trail), double (trail with operator and one passenger), freestyle (off trail), and lake driving. Statistical analysis of this database was performed, and a five-mode steadystate snowmobile engine duty cycle was developed. A test procedure, based on this five-mode duty cycle, has been defined, addressing requirements specific to snowmobile engines. A round-robin testing program was conducted by International Snowmobile Manufacturers Association (ISMA) member companies to validate and further develop this test procedure. Supporting emissions test results and analysis are presented on two snowmobile engines tested at six different laboratories.