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Detroit Diesel says the first of its anticipated new worldwide series of engines is the DD15, a 14.8-liter inline six-cylinder model that will debut in North America in spring of 2008.
The company said the heavy-duty engine will be offered here in Freightliner, Sterling and Western Star trucks in ratings of 455 to 560 horsepower with torque of 1,550 to 1,850 pounds-feet. It will replace the Series 60, the company's main engine for the last 20 years.
The new Heavy Duty Engine Platform will also include a higher-horsepower 15.6-liter DD16 and a 12.8-liter DD13, which will replace the current MBE 4000. There'll also be a 10.6-liter version which may or may not be offered here.
DD15's features include two overhead camshafts; turbo-compounding, where a second turbocharger is geared to the crankshaft; and an Amplified Common Rail System that delivers fuel at very high pressures via electronic fuel injectors. All are managed by an enhanced Detroit Diesel Electronic Control system.
Development of the new engine platform began in '02 and represents an investment by Daimler Trucks of $1.5 billion, including $275 million to retool the plant in Redford, Mich., near Detroit, where the DD15 was unveiled. The DD15 will be built there and in Germany and Japan, where it will have Mercedes-Benz and Fuso names. About 90 percent of the engine's parts will be common and shared among the three production facilities. Freightliner, Sterling-Western Star, M-B and Fuso are sister companies under Daimler of Germany.
The engine will meet the federal EPA's tighter exhaust emissions limits for 2010, as well as next year's Euro 6 and the JA '09 limits in Japan. EPA versions will use higher levels of exhaust-gas recirculation (EGR) and selective catalytic reduction (SCR) to lower output of nitrogen oxides (NOx). SCR, now successfully used by Mercedes and others in Europe, injects small amounts of urea into the exhaust to cause a chemical reaction that breaks down NOx into nitrogen and water vapor; this also helps reduce fuel consumption by 2 to 5 percent compared to the Series 60.
Helping is the turbo-compounder, which is spun by exhaust gases after they leave the primary turbo; it converts exhaust energy to mechanical force via an idler gear connected to the crankshaft. Detroit says it's the first to use turbo-compounding in a truck engine. Other builders now use double turbocharging and more will in upcoming models, but the high- and low-pressure "series" turbos only compress inlet air.
Turbo-compounding also boosts performance, and DD15's torque response is up to 75 percent better than the Series 60's, engineers said. Pre-production versions of the DD15 showed especially strong low-end performance during brief drives by qualified reporters on steep grades at Chrysler's proving grounds outside Chelsea, Mich. (Daimler still owns 19.9 percent of Chrysler LLC.)
Enhanced retarding is also a DD15 feature, thanks to an integrated Jacobs Engine Brake that's driven by one of two overhead camshafts (the other cam operates the valves). The three-stage brake works on two, four or six cylinders. It's quiet, yet develops up to 500 retarding horsepower — enough to control and even slow a 65,000-pound rig on 12 to 15 percent downgrades at the proving grounds.
The engine is compact, with a length of 56.1 inches, and will easily fit in conventional and cab-over-engine trucks, executives said. Easy servicing was among the design goals for the DD15, and its basic oil-change interval is 40,000 miles.
Freightliner's new Cascadia highway tractor will be the first to get the DD15. By fall, it will be available in Western Stars and Sterling A and L models.
