2010 Engine Performance
“Prior to EPA10,” he adds, “the maximum horsepower produced by [the D13] was 485 with 1,650 lb.-ft. of torque.” Today, the engine is capable of 500 hp with 1,750 lb.-ft. of torque.
The 2010 fuel economy improvements are best viewed alongside diesel exhaust fluid (DEF) consumption rates, given that any boost in the former will be tempered by the necessity of buying the latter.
“The price of bulk DEF is relatively close to the price of diesel, or a little less,” says Duley. “We’d rather have to use a gallon of DEF to save a gallon of fuel. The 2010 trucks have shown about a 5 percent improvement in diesel fuel consumption, although some manufacturers are better than others. DEF consumption rates vary by manufacturer, too, between 2 and 4 percent, so we watch that carefully.”
Fancher reports an average 5 percent fuel economy improvement with Volvo engines, compared to 2007. One carrier making dedicated runs owns five Volvos, he says, “three of which are 2011 VN670s with D13 425-hp SCR engines. He says his uptime with these units is greatly improved and his fuel economy is close to the 7.0 mpg mark, an almost 10 percent improvement over his older units.”
A 150-truck fleet in Alabama ordered one VNL630 with a D13 475-hp SCR engine as a test in January 2010. “It’s been running problem-free all that time and is delivering about a half mile per gallon better fuel economy than the rest of their trucks,” Fancher says.
Ellison gave an example of an over-the-road truck, comparing similar 2009 and 2010 Cummins engines. The truck could easily reduce fuel consumption by 6 percent and need 2 percent of total fuel in DEF, which would end up costing about $600 per year per truck. The net savings would approach $2,800 per truck per year.
Williamson says Detroit Diesel customers are reporting “up to 5 percent better fuel economy compared to 2007,” which the company promised. “Our customers have also commented on exhaust fluid consumption being in line with estimates of 2 percent of diesel fuel.”
Mack’s also seeing a “solid 5 percent improvement in fuel economy,” says McKenna. “We predicted DEF consumption at a rate of 3 percent relative to the diesel fuel. We are actually seeing something closer to 2.2 percent overall – slightly higher with winter grade fuel.”
While one might expect higher levels of regeneration from International than competitors’ vehicles with their lower engine-out NOx, Shick says the materials used in its diesel particulate filter have been changed to keep the unit hotter, and exhaust temperature can also be ramped up to help keep the unit clear. The ECM watches soot-related backpressure and controls the interstage cooler and an exhaust brake that remains on the engine to heat up the exhaust and avoid the need for active regeneration under many conditions.
He adds it also helps that the engine delivers “full torque at 1,000 rpm. Our customers have experienced the same or better fuel economy in every application,” Shick says. “This is beause our engine is integrated into the truck, and we’ve made aerodynamic improvements, reduced weight, and reduced parasitic losses, for example by adopting a clutched air compressor that shuts down once the air brake pressure has reached the cutoff point.” With no DEF, this should mean low operating costs.
The added weight of SCR components is an issue for all makers but International. Duley says, “With all of the emission components we have added over the last few years, there has been an overall increase in weight, and that weight tends to be toward the steer axle. The 13,000-pound axle and properly rated tires give that extra margin that could keep you out of trouble.”
Contrasting 2009 weight with that of the current setup, Ellison says, Cummins took 70 pounds out of the engine by removing the injector camshaft. He estimates DEF weight at 162 pounds with an 18-gallon tank. Cummins’ specification for the 2010 aftertreatment system weight is 202 pounds. But if the total cost of fuel plus DEF drops as significantly as is claimed, and maintenance costs decline as well, the end result could be a more profitable operation, even with a small decrease in payload.