NAPA VALLEY, Cal. –Detroit Diesel’s popular DD15 engine has a new little brother.

The 12.8-litre DD13 was introduced to unsuspecting trade press editors at a Sterling Trucks event here in early August. The six-cylinder, in-line engine will be well-suited to applications where Sterling has a strong presence, namely LTL, regional distribution and vocational markets.

The engine, which will replace the MBE4000, will be available with 350 to 450 hp and 1,350 to 1,650 lb.-ft. of torque.

The DD13 was built with reliability in mind, and has a B50 rating of one million miles, meaning 50% of the engines will last a million miles. By comparison, the Series 60 had a B50 rating of 750,000 miles, Detroit Diesel officials announced.

The DD13 is expected to provide 5% better fuel mileage than the MBE4000, thanks to an efficient Amplified Common Rail Fuel System (ACRS).

“The DD13 is the only engine in its class to offer ACRS,” said Admir Kreso, director HDEP engineering with Detroit Diesel.

David Siler, director of marketing with Detroit Diesel, added ACRS “delivers fuel with higher pressure and with more flexible and precise measurements,” which results in “lower engine-out emissions without the customary fuel economy penalty.”

The fuel system features a relatively low fuel pressure to reduce the potential for leaks at connection points, Siler explained, but in the injector itself the fuel pressures is boosted to up to 32,000 psi.

Unlike the DD15, the newest member of the family will not use turbo-compounding, because Detroit Diesel engineers wanted to allow for rear-PTO capabilities.

“The PTO capabilities of the DD13 will be as diverse and universal as any that Detroit Diesel has offered before,” said Siler, noting the types of applications best suited for the DD13 won’t benefit as much from turbo-compounding as line-haul does.

The DD13 shares 65% of its parts with its bigger brother, simplifying maintenance and repairs for fleets using both engines.

“Many of the most commonly replaced items, such as filters and belts, are already in stock at dealers and distributors and we’re still several months before the start of production,” Siler said.

The DD13 weighs about 400 lbs less than the DD15, albeit it’s slightly heavier than the MBE4000. Siler said the engine boasts a wide sweet spot and pulls strong down to 1,100 RPM. Its peak torque band is 500 RPM wide, Siler said.

“We all know getting into higher gears sooner and staying there longer, reduces fuel consumption,” he reasoned.

The new engine also features an enhanced cooling system that prefers to run hotter, minimizing fan-on time.

“For every moment the fan is cycling on, that’s up to 50 hp of parasitic load,” Siler pointed out.

Another benefit of the DD13 is its extended service intervals. The engine can go up to 50,000 miles before requiring routine maintenance such as oil and filter replacements -nearly double the length of some competitive engines, Detroit Diesel claims. When it does come time to perform routine maintenance, upright, easily-accessible filter cartridges make the job easier and tidier, Siler noted.

Another feature to be enjoyed by drivers is a quiet, lightweight Jake Brake capable of up to 546 braking horsepower by shutting down two, four or six cylinders.

The DD13 will initially be available in Sterling and Freightliner trucks beginning in 2009.Western Star will receive the engine in 2010. The engine was designed to be compatible with a Selective Catalytic Reduction system in 2010. •