Detroit Enhances Engine Families with Fuel Economy in Mind

A sign posted in the office proclaims ‘This is Detroit,’ and it is right in every sense of the word. This is the home of a brand that shares its name with America’s motor city, and the Detroit name is gradually taking hold as the Diesel reference is removed from old Detroit Diesel signs around the Michigan facility.
But even as the word disappears from the signs, it is obvious that diesel remains an important focus. It was certainly at the top of mind as engineers worked on their latest product upgrades – leading to engines that promise to consume less fuel.
Detroit has unveiled several enhancements for its 2013 engine family, all of which play an important role in meeting 2014 regulations from the Environmental Protection Agency and National Highway Traffic Safety Administration, placing tighter controls on greenhouse gases (GHG) and delivering better fuel economy in the process.
“It is our goal to pace the industry in emissions compliance and fuel efficiency. Early submissions for GHG14 engine compliance is evidence of this strategy for the updated family of Detroit engines,” said Brad Williamson, Daimler Trucks North America’s manager, engine and component marketing.
Various changes will be seen in the DD13, DD15, DD15 TC, and DD16 engines.
The DD15 engine platform includes the widest array of upgrades and will be exclusive to the Freightliner Cascadia Evolution.
“This is the flagship product,” says Mark Groeneweg, director, truck engine product engineering at Daimler Trucks. “We have a focus here on low cost of operation and we think there’s a big, big customer benefit to be had.”
New components in the 14.8-litre engine include a liquid-only delivery system for the diesel exhaust fluid (DEF), eliminating the need for an air-assisted delivery method. This helps to reduce the load on the engine’s compressor, and applies the fluid in a spray pattern that more efficiently attacks NOx created in the combustion process.
Detroit has also eliminated one of the elements in the engine’s traditional fuel filter, introducing a design with a single element, a pre-screen, and a 100,000-mile recommended service interval that doubles the life of its predecessor. The new module will require fewer priming strokes, and offers easier access to the water drain. Meanwhile, an in-dash restriction indicator will tell drivers about the upcoming need to change the filter.
Several changes are helping to reduce the parasitic loads that would otherwise waste fuel. The existing water pump with a fixed drive, for example, is being replaced with a variable-speed design. “This allows us to not pump coolant when we don’t need it,” Groeneweg says, referring to the feature already found on Mercedes Actros engines in Europe.
Rather than using a variable turbocharger, the DD15 will also include a new fixed-geometry turbocharger that is fine-tuned to optimize engines with popular fleet ratings of 455 hp and 1,550 lb.-ft. of torque.
“This is not an off-the-shelf bought component,” Groeneweg adds, referring to the turbine’s refined shape and compressor wheel.
The fuel itself will be introduced through an amplified common rail system (ACRS), which helps Detroit to shape the engine’s rates. “It gives us a big knob to turn to keep the formation of NOx low, but get the fuel in fast,” Groeneweg explains. Injection nozzles have also been adjusted to reduce friction.
In-cylinder changes include pistons with improved oil control rings that – combined with ACRS – deliver higher injection pressures for better combustion controls. And a “carbon scraper ring” inserted at the top of the liner will peel unwanted carbon off the top of the piston, protecting against the contaminants that would otherwise polish the bores.
Electronic upgrades come in the form of faster processors and extra memory, in part to prepare a system that will be able to manage inputs from Detroit’s 12-speed automated transmissions, which were recently unveiled to round out the company’s powertrain offerings that also include axles.
“With the modifications we’ve made to the DD15, we are not only meeting compliance standards, but we’re providing our customers with a reliable solution that can provide significant fuel economy gains,” said Williamson. “And, with the recent introduction of the Freightliner Cascadia Evolution, we were able to showcase the power and performance of the enhanced engine.”
The company will offer the DD15 TC (with turbo-compounding) in other trucks, and that engine will come with many of the DD15’s upgrades including improved electronics and the single-element fuel filter. This design, says Williamson, “is kind of a go-anywhere, do-anything engine, depending on the weight and application.” It will be available in many Freightliner and Western Star models.
Horsepower-hungry Canadian buyers of today’s DD15 may need to look to the DD16 for some of their traditional ratings. While the DD15 was traditionally available with up to 560 hp and 1,850 lb.-ft. of torque, it now comes with between 455 and 505 hp and 1,550 to 1,750 lb.-ft. of torque. The enhanced DD16 now delivers 475 to 600 hp and up to 2,050 lb.-ft. torque.
Meanwhile, enhancements to the Detroit DD13 – offered with ratings from 370 to 470 hp and 1,250 to 1,650 lb.-ft. of torque – include changes to the fuel filter module, and an optional variable speed water pump that is more efficient than a gear-driven design. The engine’s buyers with LTL fleets are likely to be among those most interested in adding the feature that will be standard fare in the upgraded DD15.
A new crankcase sensor has also been added to support on-board diagnostics that need to be enhanced in 2013. The sensors and warning lights that first began to monitor emission-controlling equipment in 2010 will now need to watch over fuel, air, EGR, and cooling systems; crankcase ventilation; diesel particulate filters; selective catalytic reduction; sensors; and actuators.
Buyers will be able to order engines that meet the GHG14 standards without making any radical changes in their purchasing habits. At this point, for example, there will be no need to order locked vehicle speed limiters in a Detroit Diesel engine.
In the coming months, the real-world tests will continue as Daimler Trucks North America looks to prove the value of its engine enhancements. It is already running 30 DD15s in Freightliner Cascadia Evolution sleepers and 10 DD13s in day cabs. Those have been handed over to fleets after 10,000 miles of testing in Portland, Oregon.
The early results are promising. When comparing the average load on an EPA2010 engine to the GHG14 models, fuel economy has improved about 6.7%. “We’re off to a very, very positive start with this program,” says Tim Tindall, Detroit’s director, component sales.
A second round of test trucks and engines to be built in August will include 26 DD15s, 16 of which will have Detroit transmissions, and 35 day cabs powered by DD13s in Cascadia day cabs.
All of the rucks come with the “visibility package” in Detroit’s Virtual Technician system that can be used to track performance at any point in time, offering data such as the amount of fuel being consumed, distances traveled, fault codes, and vehicle locations.
The question that remains is when most customers will begin to buy the equipment. Past rounds of tightened emission controls led many fleets to “pre-buy” engines based on standards that existed before any changes took place, and slowed the introduction of cleaner technologies that carried higher price tags.
But the GHG14 engines could represent an important difference. This time, equipment upgrades will offer better fuel economy that can deliver return on the investments.
Tindall doesn’t personally expect a pre-buy this time around.
The real question is whether some customers choose to postpone their purchases until the more fuel-efficient models are available, he says. “Some customers have asked us about that already.”