New Duramax highlights GM's package

GM HAS INTRODUCED a new 6.6L Duramax 6600 turbodiesel V-8 (RPO LBZ) for the 2006 model year Chevy Silverado HD and GMC Sierra HD with class-leading horsepower (360 at 3200 rpm) and class-leading torque (650 lb-ft at 1600 rpm).

“Those are some pretty phenomenal numbers,” said product/marketing manager Dan Tigges.

In addition to the power increase in the Silverado and Sierra, all 2006 Duramax engines have been significantly revised to deliver lower emissions and significantly improved quietness and smoothness in every application.

The 2006 Silverado HD and Sierra HD with the Allison 6-speed automatic transmission were equipped with a significantly revised 310 horsepower Duramax 6600 (LLY) through the third quarter of 2005. It was replaced in these applications in the fourth quarter of 2005, by the higher output, 360-hp Duramax (LBZ).

GM is hoping to experience a boost similar to what happened with the introduction of the Duramax diesel in 2001, which propelled GM's heavy-duty diesel pickup truck market share to over 25 percentage points.

The Duramax 6600's horsepower and torque increase and emissions reduction are enabled by a strengthened iron cylinder block and a lower compression ratio. The lower compression reduces stress on the engine by reducing the peak cylinder firing pressure. This, in turn, allows more fuel to be burned — more fuel means more power — while the lower compression helps reduce NOx emissions. Lower compression also helps reduce noise and vibration, making all variants of the 6600 a quieter and smoother engine.

A revised variable-geometry turbocharger also enhances the driving experience of the Duramax 6600. Aerodynamic changes to the turbo's vanes help tailor controlled application of turbo power for seamless and immediate response at full throttle. The turbo, which spins at up to 120,000 rpm, is high-speed-balanced, reducing vibration and resonance — and contributing to the engine's overall smoothness and refinement. The revised turbo also helps reduce emissions, while maximum boost remains at 20 psi.

Another new feature of the DURAMAX 6600's turbo system is the capability of the variable-geometry turbocharger to provide exhaust braking. This function is available on some medium-duty truck models and can replace add-on exhaust brake hardware. With the new system, braking is controlled by a signal from the engine controller and can be activated by the driver.

Changes and upgrades

Changes and upgrades to the 2006 DURAMAX 6600:

  • Cylinder block casting and machining changes strengthen the bottom of the cylinder bores to support increased horsepower and torque.

  • Upgraded main bearing material increases durability.

  • Revised piston design helps lower compression ratio to 16.8:1 from 17.5:1.

  • Piston pin bore diameter increased for increased strength.

  • Connecting rod “ I ” section is thicker for increased strength.

  • Cylinder heads revised to accommodate lower compression and reduced cylinder firing pressure.

  • Maximum injection pressure increased from 23,000 psi to more than 26,000 psi.

  • Fuel delivered via higher-pressure pump, fuel rails, distribution lines, and all-new, seven-hole fuel injectors.

  • Fuel injectors spray directly onto glow plugs, providing faster, better-quality starts and more complete cold-start combustion for reduced emissions.

  • Improved glow plugs heat up faster through an independent controller.

  • Revised variable-geometry turbocharger is aerodynamically more efficient to help deliver smooth and immediate response and lower emissions.

  • Air induction system re-tuned to enhance quietness.

  • EGR has larger cooler to bring more exhaust into the system.

The Duramax 6600 also has a new intake air heater to reduce smoke and emissions during cold or light-load driving. The system features a 1000-watt grid heater located in the air intake duct, which is triggered automatically by the engine controller. It heats up the incoming air to speed warm-up of the engine.

The DURAMAX 6600 features a rigid cast iron cylinder block with induction-hardened cylinder bores; four-bolt, cross-drilled main bearing caps; forged steel, nitride-hardened crankshaft; aluminum pistons with jet-spray oil cooling; aluminum cylinder heads with four valves per cylinder; integrated oil cooler and a charge-cooled turbocharging system. Features, such as easy-access fuel filter and timing gears, reduce maintenance time and effort.

A new, 32-bit E35 engine controller monitors and adjusts the engine's operation. Designed exclusively for the Duramax diesel engine, the controller helps the injectors precisely meter fuel to the cylinders and can compensate for the variability of the injectors and fuel flow. This sophisticated, more powerful controller also can support up to five injections per cylinder and eliminates the need for an engine-mounted drive unit to fire the fuel injectors. The new DURAMAX 6600 in the Silverado and Sierra heavy-duty pickups will be available exclusively with the new Allison 1000 6-speed automatic transmission, featuring class-first features, such as tap-shift range selection mode.

In addition to the Chevy Silverado HD and GMC Sierra HD, the Duramax 6600 (LLY) is also available at varying power outputs in the Hummer H1 Alpha, Chevy Kodiak, and GMC Topkick. For 2006, the Duramax is available for the first time in GM's full-size vans, Chevy Express, and GMC Savana, providing power and capabilities matched with quietness and smoothness not found in competitors' diesel-equipped vans.

The DURAMAX 6600 is assembled at the DMAX facility in Moraine, Ohio , a joint venture between GM and Isuzu created specifically to produce diesel engines.

Market share

Tigges said Sierra's market share in '04 was up 21% over '03 and is up 15% this year over the first half, and Silverado's market share in '04 was 10% over '03 and is up 10% this year.

“We've consistently gained market share, and we feel very good about where we're going, and where the next generation is going to take us,” he said.

He said that starting with the fourth quarter of 2006, GM will switch from its current generation truck to the next generation truck, starting with light duty and going to heavy duty.

“Once we get to 2008, we will have all of our products in the new 900 generation trucks to hold our competitive advantage,” he said. “We are not providing any information yet. The first public showing will be a few months prior to the launch.”

He said measurement meetings will be held in February or March of 2006 for LD and in August or September for HD, including box delete as well as an update on LD products. Those meetings are for manufacturing members only.

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