Behind the Fuel Economy Scenes At Kenworth

They look like regular over the road trucks, but the drivers behind the wheel aren't delivering freight -- they're on the road testing design enhancements and fuel economy.
It's all part of Kenworth's ongoing research and development program.
"We don't work in a vacuum," said Jim Bechtold, Kenworth's chief engineer. "Our design and testing goes beyond computers and wind tunnels. We take what our engineers create and test it over the road to verify our initial findings. Then we bring the advancement to market."

According to Bechtold, Kenworth's professional drivers run several routes, ranging from 150 to 500 miles. "Each route has its own unique elements," Bechtold said. "For example, one run simulates on-highway long hauling, while another provides a 4,300-foot elevation gain to test performance in tough mountain conditions."
Last year, Kenworth conducted numerous round-trip, fuel-economy runs from its R&D Lab in Renton, Wash., to The Dalles, Ore., a small town on the wind-swept shores of the Columbia River.
"We typically ran two identically spec'd trucks -- with the exception of the engine -- to The Dalles and back," said Moses Luyombya, Kenworth's fuel economy project engineer. "It's a good real-world test route because we encounter a lot of extreme weather conditions, especially traveling up the windy Columbia River Gorge to The Dalles."
Many of these real-world runs featured the aerodynamic Kenworth T2000 -- operating with different engine models. The similarly spec'd T2000s all had a GCW of approximately 74,000 pounds with a gap of 42 inches between the tractor and trailer. The combined runs covered a total of 6,000 miles.
To make each test as accurate as possible, Kenworth switched drivers and trailers halfway through the trip. "This eliminates any variables in driver performance," Luyombya said. "When the day is done, we measure fuel and any difference we find in mpg between the two vehicles shows the direct correlation that the test component had on aerodynamics."
Kenworth engineers documented fuel mileage of up to 7.69 miles per gallon. All the results came in over 7 mpg with the lowest at 7.24. Overall, the T2000 averaged 7.43 miles per gallon during these 500-mile, roundtrip runs to The Dalles.
While real-world fuel economy tests are intended to validate computer simulations and wind tunnel findings, Kenworth also tests new aerodynamic devices, or vehicle configurations to better assist customers in proper spec'ing. "The way a tractor interacts with a trailer has a big impact on fuel savings," said Luyombya. "We've refined roof cap heights and shapes - and recently explored new devices to reduce the air flow drag behind the trailer."
Kenworth also is involved in testing conducted at the Paccar Technical Center, which features a 1.6-mile oval high-speed truck. The closed circuit track tests cover at least 150 miles.
To give engineers accurate and consistent results, tests involve a modified tractor-trailer and a control combination. Their miles per gallon are compared over three separate runs, and the numbers must be consistent in order for the test to be verified.
Last summer, fuel-economy test runs at the PACCAR Technical Center also featured the aerodynamic Kenworth T2000 -- operating with different engine models. The similarly spec'd T2000s all had a GCW of 74,000 pounds with a gap of 43 inches between the tractor and trailer. The combined runs covered over 2,000 miles.
"Similar to the T2000 road tests, we documented up to 7.68 mpg for the T2000 during the tests on the Tech Center track," Bechtold said. All the results again came in over 7 mpg with the lowest at 7.18. Overall, the T2000 averaged 7.42 miles per gallon during these tests.
Added Bechtold, "The advantage of this closed circuit track testing is that it's so accurate that we can detect small differences in fuel economy that can't be documented on road tests."
To assist fleets and owner operators interested in improving their fuel efficiency, Kenworth recently launched a major Fuel Economy Awareness Program. Kenworth also has produced a "White Paper on Fuel Economy," which can be electronically downloaded at the "Dynamics of Fuel Efficiency" link at www.kenworth.com. The white paper includes the actual T2000 results from the Renton to The Dalles and PACCAR Technical Center test runs.