Effect of North American Certification Test Fuels on Emissions from On-Road Motorcycles 2021-01-1225

Chassis dynamometer tests were conducted on three Class III on-highway motorcycles produced for the North American market and equipped with advanced emission control technologies in order to inform emissions inventories and compare the impacts of existing Tier 2 (E0) fuel with more market representative Tier 3 and LEV III certification fuels with 10% ethanol. For this study, the motorcycles were tested over the US Federal Test Procedure (FTP) and the World Motorcycle Test Cycle (WMTC) certification test cycles as well as a sample of real-world motorcycle driving informally referred to as the Real World Driving Cycle (RWDC). The primary interest was to understand the emissions changes of the selected motorcycles with the use of certification fuels containing 10% ethanol compared to 0% ethanol over the three test cycles. Generally, for most of the test motorcycle/drive cycle combinations, the use of E10 certification fuels compared to Tier 2 (E0) resulted in reductions in CO, HC, NMHC; with some FTP and RWDC tests showing increased NOx emissions. Reductions in CO₂ with the use of E10 fuels were noted with N₂O and CH₄ emissions having little impact onCO₂ equivalent emissions. PM mass emission rates were below 1 mg/km with no discernable trends concerning fuel changes. Tier 3 and LEV III E10 fuels also resulted in emissions changes to a suite of air toxics, including 17 carbonyl compounds, 1,3-butadiene, BTEX, styrene, and five C9 aromatics. Acetaldehyde emissions increased significantly with the E10 fuels for all motorcycle/drive cycle combinations, while toluene and benzene emissions decreased. The estimated ozone formation potential of the 30 compounds was reduced with the E10 fuels compared to Tier 2. Overall, this study, which examined the emission profiles of multiple motorcycles, test cycles, and in-use driving samples, provides insights on the emission inventory impacts from the introduction of ethanol-containing fuels, over a range of motorcycles, reflective of the North American in-use fleet.