Identical wheel loaders in the 190- to 200-horsepower class were used as host machines for the Fuel Duel. The 6.7-liter QSB engines — one certified to Tier 3 emissions limits and the other performing to Tier 4 limits — competed back-to-back in the Fuel Duel. They were specified with the same power output, peak torque and rated speed.
Various duty-cycle tests included short and long cycle times with minimal idle time to represent real-world operation. The machines undertook a sequence of pile breakout and bucket discharge testing, together with repeated sprints and braking. Both the Tier-3 and Tier 4 Interim (T4i)-powered machines were operated by the same driver with the same bucket size and tire pressure.
The higher fuel efficiency of the T4i engine was achieved without compromising machine performance. In fact, the T4i machine completed the Fuel Duel tests with shorter cycle times due to a faster engine response to load demands. The T4i standard will affect this engine class in 2011.
The T4i engine's fuel efficiency advantage included active regeneration of the diesel-burning Cummins Particulate Filter. Fuel used in regeneration was barely measurable, as the filter cleaned itself in passive regeneration mode for much of the operating time.