New 2011 GMC Sierra Heavy-Duty Trucks Deliver Best-in-Class Diesel Torque and Horsepower

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Mar 10, 2010, 12:01 ET

PONTIAC, Mich., March 10 /PRNewswire/ --

New 6.6L Duramax turbo diesel rated at 397 hp (296 kW) and 765 lb.-ft. of torque (1,037 Nm)
Segment-best diesel power complemented by up to 11-percent improved fuel economy and up to 63-percent reduced NOx emissions
Small-block 6.0L gas V-8 enhanced for greater low-rpm torque, while delivering 360 hp (268 kW)

The new 2011 GMC Sierra heavy-duty pickups are offered with a new 6.6L Duramax turbo-diesel V-8 that tops the segment in power. It is rated at 397 horsepower (296 kW) at 3,000 rpm and 765 lb.-ft. of torque (1,037 Nm) at 1,600 rpm.

The new, more powerful 6.6L Duramax is also more fuel-efficient – up to 11-percent greater fuel economy than the outgoing model – reduces NOx emissions by up to 63 percent and helps enable greater towing ratings. Sierra 3500HD can tow up to 20,000 pounds (9,072 kg).

"Segment-leading power is great, but it's not the only thing that makes the new Duramax a winner," said Gary Arvan, Duramax chief engineer. "We designed the engine to make that power with less fuel and fewer emissions, while also increasing its durability. Customers will immediately feel the difference in power and, over years of service, appreciate all the other attributes that make it a dependable engine for any task."

Among the 6.6L Duramax turbo diesel's new and enhanced features are:

Main bearing profiles changed to enhance oil film thickness
Oil pump flow increased for more pressure at low speeds
A revised turbocharger oil circuit for increased pressure at the turbo and faster oil delivery
Connecting rod pin ends modified to provide increased piston support
New, higher-strength piston design
A new 30,000-psi (2,000 bar) piezo-actuated fuel injection system – capable of operating on ASTM grade B20 biodiesel – ensures more precise fuel delivery, improving emission performance
An EGR cooler bypass reduces high-mileage soot deposits in the cooler and EGR circuit (pickup versions only).

A slightly different version of the 6.6L Duramax is offered in Sierra HD chassis cab and box-delete models. It is based on the same improved architecture and includes most of the same features as the pickup version. However, it is engineered to meet federal certification standards for incomplete vehicles, including the incorporation of a robust EGR system. It is rated at 335 horsepower (249 kW) at 3,100 rpm and 685 lb.-ft. of torque (928 Nm) at 1,600 rpm.

Strong small-block 6.0L V-8

The standard engine in Sierra HD trucks is the Vortec 6.0L small-block V-8, which is enhanced for 2011 with greater idle refinement. It is rated at 360 horsepower (268 kW) at 5,400 rpm and 380 lb.-ft. (515 Nm) at 4,200 rpm in Sierra Denali HD, 2500HD and 3500HD pickup models. In chassis cab and box-delete models, as well as pickups with a GVWR greater than 10,000 pounds, it is rated at 322 horsepower (240 kW) at 4,400 rpm and 380 lb.-ft. (515 Nm) at 4,200 rpm.

Approximately 90 percent of the Vortec 6.0L's peak torque is available by only 2,000 rpm and excellent fuel economy is enabled by the engine's low-friction OHV configuration and cam phasing. The state-of-the-art small-block architecture of the Vortec 6.0L – known commonly as the "LS" family – delivers great strength, smoothness and durability.

SOURCE General Motors