The completely new heavy-duty Detroit Diesel DD15 engine is the first of a trio of engines for world markets set to make its NAFTA debut in Freightliner Cascadia models beginning next April. It will be followed by Century S/T and Columbia trucks and then the Coronado, Western Star, and Sterling L-line and A-line models later in 2008.

It’s a platform that will eventually be shared among all Daimler Trucks worldwide, including Mercedes-Benz trucks built in Europe and Mitsubishi Fuso trucks in Japan. It will replace the four distinct engine series used today by Daimler Trucks brands globally, and will be manufactured at the company’s plants in Mannheim, Germany and Kawasaki, Japan as well as the Detroit Diesel factory in Redford, Michigan.

The new motor is an in-line six with four valves per cylinder and two overhead cams that was born EPA-’07 compliant (via cooled EGR and a particulate filter) and is ready to meet EPA ’10 with the addition of just a downstream selective catalytic reduction (SCR) exhaust aftertreatment system to meet the lower NOx standards. The engine will first be offered in a 14.8-liter displacement, the DD15, later in 12.8 and 15.6 liter models – the DD13 and DD16 respectively — with modifications only to the cylinder liners. Everything else on the engine will stay the same..

The new engine will be offered in variants from 455 to 560 hp and 1550 to 1850 lb ft in its initial 14.8-liter trim. When the 15.6-liter comes out in 2010, it will get up to 630 hp and 2050 lb ft. The 12.8-liter version, the DD13, will eventually replace the MB4000, with torque ratings between 1250 and 1650 lb ft.

This engine isn’t at all a re-purposed and repackaged Series 60, which is now 20 years old. It’s a brand new, clean-slate design that incorporates a number of performance-improving enhancements. Chief among them is the Amplified Common Rail System (ACRS) that optimizes combustion efficiency and reduces noise dramatically. As well, Turbo Compounding adds “50 free horsepower to the engine,” Detroit Diesel says. There are two turbos on the engine, the first operating in a traditional air-management capacity to boost intake pressure, while a second turbine wheel is linked by a viscous clutch directly to the engine’s rear gear train. Exhaust spins the second turbine wheel, adding that much more power to the engine’s total output.

Detroit’s current engines, the Series 60 and the MBE4000, will be available until 2010, when they’ll be phased out.