When it comes to aerodynamics, Kenworth Chief Engineer Joe Adams said that “upping the bar” is synonymous with the name Kenworth.
“It’s what Kenworth has been known for since 1985 when we introduced the industry’s first truly aerodynamic truck – the Kenworth T600. We’ve never lost sight of pursuing continuous improvement,” said Adams.
The Kenworth T680 Next Generation is the next phase in this tradition. “Our design enhancements offer up to 6 percent* fuel efficiency on a T680 Next Gen equipped with a 76-inch sleeper and EPA 2021 PACCAR MX-13 engine over a comparably spec’d T680 with EPA 2017 PACCAR MX-13 engine,” said Adams.
To gain even more fuel efficiency, Kenworth invested in aerodynamic simulations to develop each individual component of the T680 Next Gen as part of the total system, while verifying results through wind tunnel testing.
Through analysis and verification, the team also took air a different direction – under the chassis instead of only around the truck. “Managing the air under the truck is the approach we took and it worked well,” said Adams. “Changes to the hood and bumper keep airflow closer to the cab and reduce turbulence. The hood is eight inches narrower than before. The restyled, aerodynamic bumper maintains the same approach angle and ground clearance as the classic Kenworth T680.”
The bumper has an improved profile to direct air past the wheel openings improving aerodynamics. The unique air dam design guides and controls airflow under the chassis while providing protective coverage under the cooling module. It features an offset radar allowing for a robust center-mounted license plate holder.
According to Adams, Kenworth also developed a unique ducting system within the hood structure. It features a passive flap from the underbody to the outerbody actuated by air. It opens and closes behind the fender based on air pressure and wind conditions, which streamlines air movement.
Kenworth also made fairings advancements. “It starts with undercab chassis fairings that manage airflow off the hood, while adding larger steps for easier entrance to the cab,” explained Adams. “The fairings have great impact resistance, plus rolled edges for a cleaner look. The new attachment system we developed means easier and faster fairing replacement if a repair is needed.”
Behind the cab, Kenworth now has optional side extenders that extend an additional 9 inches – 28 inches in total length — which helps close the tractor/trailer gap and smooth airflow from the top and sides of the tractor onto the trailer. Providing a good fuel economy benefit, the side extenders can be spec’d to open on either side of the tractor to allow frame and component access.
Other aerodynamic features include an A-pillar turning vane that reduces the size of the air wake next to the side windows, plus tandem drive axle fairings that smooth air from the chassis. These two features offer fuel economy benefits. The new, stylish, air intake system also provides aero benefits.
“All told, we think the T680 Next Gen will become the new standard when it comes to fuel economy,” said Adams. “Coupled with the sleek look of the truck, it’s going to raise eyebrows.”
*Individual fuel economy improvement will vary depending on use, road conditions and other factors.