Fueling Kubota RTV900 Utility Vehicles with D2 and B20: Results of In-Use and Laboratory Studies

Abstract

In-use and laboratory studies were conducted comparing NOX emissions, fuel efficiency, engine wear, engine torque, and engine power for Kubota RTV900 general purpose utility vehicles fueled with Number 2 low-sulfur petroleum diesel (D2) (eight vehicles) and a 20% biodiesel blend (B20) (eight vehicles). These utility vehicles were equipped with Tier IV compliant, 3-cylinder, indirect-injection (IDI) compression-ignition engines (16.1 kW @ 3200 rpm). During the in-use study there were no significant (p < 0.05) differences between fuels for corrected NOX emissions, fuel efficiency, or engine wear metals. However, during the second winter of the study, fuel gelling and filter plugging occurred in the B20 vehicles when the feedstock was switched from soybean oil to beef tallow. For the laboratory study, an identical Kubota D902-E3B engine was mounted on a stationary stand and tested. During these tests, fueling with B20 resulted in significantly (p < 0.05) lower NOX emissions at idle speed (1300 rpm); there were no significant differences in specific NOX emissions during variable-load dynamometer testing. There were no significant differences between D2 and B20 in fuel efficiency for the idle or variable-load tests. Fueling with B20 resulted in small but statistically significant decreases in torque and power at two (2900 and 3000 rpm) of the five load speeds during the variable-load tests. Based on these results, the researchers concluded that B20 is a suitable alternative fuel for Kubota RTV900 and similar utility vehicles. Use of an anti-gel additive is recommended for winter operation of beef tallow-based B20.