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Trending power options

Fleets try to spec the right engine for fuel economy and sufficient power for the application

by Carol Birkland, Contributor

While new-truck sales remain at elevated levels, fleets appear to be making a shift toward smaller vehicles and engines.

“Class 8 trucks with 12.0L to 14.0L engines are expected to surpass the 14.0L category for the first time ever in 2019,” said Kenny Vieth, president of ACT Research. He also said the straight truck segment is projected to continue to grow as more fleets order vehicles beyond the more traditional tractor-trailer combination.

Fuel economy is a key reason why there are more orders for vehicles with a lower gross vehicle weight (GVW).

“Smaller-displacement engines have a higher power-to-density ratio along with a higher volumetric efficiency, which allows increased payload with comparable performance and greater fuel efficiency,” said John Moore, product marketing manager at Volvo Trucks North America.

However, Brian Daniels, manager of Detroit powertrain and component product marketing, said there has not yet been a major shift to the DD13 from the larger DD15. He explained the company’s technical sales experts work with customers to make sure they have the right solution for the job. They find the DD13 tends to be the best fit in regional applications, while the DD15 leads the long haul segments where fuel economy and performance are most important.

Similarly, Andrea Best, product manager at Cummins, said the company “continues to see success with its B6.7 and L9 engine platforms. In fact, 2018 registration data shows an uptick in larger displacement engines, such as Cummins’ L9 engine.”

In Volvo’s case, making its transmission a 12-speed with relatively close ratios removed concerns about fuel waste due to running at too high revolutions per minute after the downshift. Downshifting at as low as 1,000 rpm and employing a closer ratio split kept the engine very close to the sweet spot, Moore said.

“Moreover, Volvo avoided power complaints by reprogramming the [engine control module] so the engine torque would remain at peak levels down to 1,000 rpm. Previously, the lower limit had been 1,100 rpm.”

The goal of downspeeding is to save fuel. Each 100-rpm reduction saves 1% of the fuel bill, an estimated $730 per year.

Engines operate best when running slowly because a slower running engine reduces friction and parasitic losses, such as driving the water and oil pumps. Because the engine then runs under more load, it effectively becomes “smaller.” This means less air needs to be ingested, less exhaust needs to be forced out, and the fuel and air in the cylinder get hotter and develop more pressure on the power stroke.

Estimates as to the amount of fuel saved hover at the 2% to 3% range.

Dominik Beckman, director of marketing and dealer operations for Hino Trucks, said there are reasons beyond sticker price why customers may choose smaller displacement engines. However, he cautioned operating conditions, payload capacity, and other factors are important to take into consideration before making a choice.

“Smaller displacement engines typically have fewer parts and are less expensive to replace and/or repair than higher displacement engines. The performance gained from a higher displacement engine may not be needed for the tasks performed by the truck, making the investment unnecessary. Also, a tax benefit could be a consideration if choosing a smaller displacement engine to avoid stepping up to Class 8 and the 12% excise tax,” he said.

Meanwhile, in the medium-duty truck market, gasoline engines are gaining some popularity. That is especially true in the Class 5 segment, where V8 and V10 gasoline engines are increasing in popularity. However, in the larger Classes 6-7 markets, 6-cyl. diesel engines remain the preferred configuration.
“In our medium-duty segment, the DD5 and DD8 are smaller displacement engines than the previous leading engines in the segment and were designed with the latest technology,” Daniels said. “We are able to get the same levels of power ratings while reducing the amount of fuel used, which means there is less exhaust that the aftertreatment has to work to clean.

“We use a simple fixed geometry turbo charger to deliver reliability and responsiveness that surpasses some of the larger engines in the medium-duty segment,” he continued.

And while fleets sort out different diesel engine options, there are a growing number of new options available.

“Alternative power is being developed, tested, and refined, while diesel engines are also undergoing transition to become more fuel-efficient and clean,” said ACT’s Vieth.

Recent electric truck introductions by both established manufacturers and newer entrants support that idea.

Volvo’s Moore notes that electric trucks provide a path to a lower carbon footprint as urban areas strive for sustainable urban development.

Although the upfront cost of electric trucks is higher than diesel trucks, they potentially allow significant savings in fuel and maintenance costs.

Since most electric trucks are driven by battery-powered systems, however, battery expenses could be a determining factor regarding whether fleets turn to these vehicles in the future.

As e-commerce sales soar, so does use of “smaller trucks”

The continued growth of e-commerce sales is leading to an increase in the use of single-unit trucks and a decline in the average length of haul, according to new research by the American Transportation Research Institute (ATRI).

Between 1999-2017, e-commerce sales increased 3,000% and now total more than 9% of total U.S. retail sales, ATRI reported. Therefore, registrations for single-unit trucks increased 7.8% between 2007 and 2016, compared with only 4.4% growth in combination truck registrations. Additionally, intraregional and last-mile truck trips are increasing, pushing down overall average trip lengths by 37% since 2000.

“These trends are game-changing, and our industry must adapt quickly to ensure that trucking continues to be the pre-eminent freight mode,” explained Tom Benusa, chief information officer of Transport America.

As a result of changing consumer patterns, “last-mile fulfillment centers” represented 73% of the industrial real estate market in 2017, a 15 percentage point increase from the previous year, ATRI said.

Retailers are decentralizing their distribution networks to bring inventory closer to consumers, and there has been a spike in courier services to ensure fast delivery.

With so many more deliveries going to congested urban areas, ATRI noted fleets and equipment manufacturers are experimenting with new technologies, including drones and electric vehicles.

“According to a study conducted by UPS, a majority (63%) of survey respondents indicated that delivery speed is important when searching for and selecting products,” ATRI wrote. “As a result, consumer expectations regarding delivery speed have forced retailers and their supply chains to accommodate shifting and shrinking delivery windows.”

Looking ahead, ATRI noted that the higher number of local e-commerce deliveries could provide an opportunity for 18- to 20-year-old commercial drivers to get involved in the industry. --Neil Abt


TAGS: Fuel News
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