January 2008, TruckingInfo.com - Test Drives
The clean-slate-design DD15 will power all Daimler, Freightliner and Mitsubishi Fuso HD trucks the world over. North Americans get it first in 2008, followed by Japan in '09, and Europe in 2010.
We're witnessing a huge change in the way trucks and engines come together. We saw it first with Volvo's D-platform engines (shared with Mack and Renault). We'll soon see International take a similar approach, sharing an engine platform between International trucks in North America and MAN chassis in Europe. Paccar is moving forward with the North Americanization of the European 12.9-liter Paccar MX engine that powers DAF trucks in Europe and elsewhere.
Now, Daimler Trucks has unveiled the DD15 engine. It's the first in a four-displacement family that will eventually power all Daimler Group trucks worldwide.
It's become too expensive to design, test and integrate separate engines into multiple chassis and to meet multiple sets of emission reductions regulations. Detroit Diesel, through its global parent company, Daimler Trucks AG - based in Stuttgart Germany - just pumped $1.5 billion into the development of this new global engine platform.
Formerly known ignominiously as the "Heavy Duty Engine Platform," we got our first official look at Detroit Diesel's DD15 in October at the company's Redford, Mich., assembly plant.
Developed from the get-go as a global engine platform, the DD15 will replace the four distinct engine series used today by Daimler Trucks brands around the world. Fully 90 percent of the componentry will be common. As the engine rolls out in different markets over time, they'll be tailored to local demands and to meet local emissions requirements.
The first model we'll see here - with full production set for next April - is the 14.8-liter version of the DD15. In 2010, we'll see a larger 15.6-liter version, which will be essentially the same engine save for a longer stroke, giving it the larger displacement. Detroit Diesel says we'll see 630 horsepower and 2,050 pounds-feet of torque out of that one.
We'll also get the 12.8-liter DD13, which is again essentially the same engine, but scaled down, and with a different block, crank, head and smaller liners. That one will launch in 2009, as the MBE 4000 heads for retirement in 2010.
The DD15 will be offered in variants from 455 horsepower to 560 horsepower and 1,550 to 1,850 pounds-feet in its initial 14.8-liter trim.
This engine isn't at all a repurposed and repackaged Series 60. It's a brand new clean-slate design that was born EPA-'07-compliant. It meets the next round of EPA regs by way of cooled EGR and a particulate filter, and it's 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. It'll go out way beyond 2010, too, because engineers went with a long-term emissions reduction strategy.
Cylinder pressures will need to be vastly higher in the future, and that sort of thing would require a complete redesign of the engine. So DD15 has the cylinder pressure capability for today, and the ability to grow for many years to come. The single-piece compacted graphite iron head boasts over a million pounds of clamping pressure to the block.
The DD15 is a 14.8-litre, in-line-six with four valves per cylinder and two overhead camshafts. It's built on a stiffer, stronger cast iron alloy block that dramatically reduces noise and vibration. It's got a rear gear train, and a forged steel, counter-weighted crankshaft with huge main- and rod-bearing journals for long life and high load-bearing capacity.
The camshafts are hollow, not solid as is usually the case. This, Detroit Diesel says, lowers the weight and inertia of the camshaft, improving throttle response. Each cam is dedicated: one for the intake valves, the other controls the exhaust valves and the integrated Jacobs engine brake.
The camshafts play no role in building pressure at the fuel injector, so the cams can be tubular and still have more than adequate strength. A gear-driven high-pressure pump maintains pressure in the common rail, with the pressure amplification accomplished inside the injector within the cylinder head.
The cylinder liners feature a unique bottom stop that allows the bottom of the liner to rest in the block. This mounting method also allows for improved coolant flow around the liner. The liners are thick too, which leads to longer life and minimizes vibration.
Liner cavitation shouldn't be an issue at all with the DD15. This engine was designed with higher coolant flow and optimized coolant galleries to avoid hotspots, which could lead to cavitation, and the rad header features a very efficient surge tank to maintain cooling system pressure while de-aerating the coolant. This also minimizes the potential for liner wall cavitation.
Insiders at Freightliner tell me they've torn down several high-mileage test engines and the liners show no signs of liner cavitation whatsoever.