Introduced four years ago as an aerodynamic Class 8 tractor and truck cab with a detachable sleeper, the Peterbilt 386 has been given a new aerodynamic package that reduces drag by another 8% and improves fuel economy by up to 4%, according to Peterbilt Motors. The key components in the new aero package will also be offered on other Peterbilt models and as an aftermarket kit later this year.
The package was developed by Peterbilt engineers using computational fluid dynamics (CFD) and the drag reduction validated in real world tests in just six months, according to Richard Mihelic, the project engineering manager. The tests included service in the Wal-Mart private fleet, which has already ordered “several hundred” 386 Aero Package trucks with 48-in. and 63-in. Unibilt detachable sleepers.
Some of the changes in the original 386 design seem fairly minor, but showed major improvements with CFD analysis, Mihelic told Fleet Owner. For example, the leading edge of the roof fairing was moved back just a few inches and the trailing edge raised a bit to generate a much smoother airflow up and over the trailer roof, he said.
Upper transitions from the cab to the sleeper were reshaped and a 3-in. rubber extender and flare was added to the sleeper fairing for improved airflow around the trailer sides and to reduce turbulence in the gap between the tractor and trailer. A small flare added to the chassis fairing also improved side airflow around the drive tires.
A new aerodynamic cab mirror contributes up to 1% of the reduction in drag, according to Peterbilt. It features a lightweight chrome housing optimized with CFD and holding fully heated primary and convex mirrors. CFD was also used to create new aerodynamic hood mirrors and marker lights.
Peterbilt engineers also looked at the 386's front bumper, but found that “the current design is very effective and didn't need to be changed,” said Mihelic.
Already in production for the 386, most of the proprietary aerodynamic package components will also be available on the Model 384 shortly, according to Peterbilt, and on the more traditional Models 388 and 389 sometime in the first quarter of the year. Aftermarket kits are also planned.
Wal-Mart played a large role in the aerodynamic refinement of the 386, according to Martin Kleker, Peterbilt's national fleet sales manager. The large private fleet worked with the truck maker's engineers to test and provide feedback on the final aerodynamic package design and even conducted its own track tests.
Peterbilt and Wal-Mart have a history of jointly developing projects intended to help the retailer meet a corporate goal of reducing its overall energy consumption, Kleker said. Last year, Peterbilt announced that it would produce the first heavy-duty diesel-electric hybrid tractors in the North American market for Wal-Mart and that the company's private fleet had also ordered the first Peterbilt-production LNG-powered trucks to be manufactured in Peterbilt's Denton, TX, plant.
“Having a partner like Wal-Mart made it much easier to commercialize these advanced technologies so quickly,” Kleker said.