2010 Engine Performance
Volvo’s coolant life, performance and service interval are unchanged, Fancher says, but “our EPA10 engines are experiencing a decrease in fan-on time because of the decrease in thermal cycling resulting from the reduction in EGR rates.”
International’s Tim Shick reports the MaxxForce Big Bore’s oil change interval, for highway engines getting 6.5 mpg, has been lengthened from 25,000 miles to 40,000 because of the addition of a Spinner centrifugal filter to remove soot. Also, the cam cover, removed every 250,000 miles to adjust the overheads, is now much easier to access.
The dosing nozzle for the DPF has also been moved to a spot where it is subject to less heat, reducing coking. This eliminates the former requirement to clean it every 100,000 miles.
A different approach to 2010
International designed its MaxxForce Big Bore engines with no selective catalytic reduction. It set its initial NOx levels at 0.5 grams, burning credits with the U.S. Environmental Protection Agency to exceed EPA’s 0.2 grams mandate.
Many experts believe that high levels of EGR tend to compromise performance. But International’s Tim Shick lists design aspects that improve performance.
The first is “an advanced turbocharging system that drives in lots of cool, clean air plus exhaust,” Shick says. Interstage cooling removes heat from the air discharged by the primary turbo before it arrives at a secondary unit. The interstage cooler uses engine coolant that’s well below operating temperature. Removing heat from the partially compressed air means the high-pressure turbo can compress the charge to a higher pressure with less horsepower and backpressure.
Although the injection system does not “run higher pressures than the industry has used historically,” he says, pressure has been increased from about 26,000 psi prior to 2010 to 32,000 psi today. The fact that the engine uses a common-rail design where “you can run full pressure at low speed,” even below the 1,000 rpm torque peak, greatly reduces soot production.
International also uses a proprietary combustion bowl. The shape is more complex, and combines with “the number of holes and spray angle, the bore size, the boost levels, and the fuel pressure, to produce inherently low emissions,” he says.
Another feature is an unusual exhaust gas recirculation cooler. Although EGR levels have been increased only “incrementally, about 3 to 5 percent,” according to Shick, the cooler has a very high capacity and brings recirculated exhaust down to “below 200 degrees.”