August 2, 2005

GM’s heavy-duty pickup trucks get new engines and transmissions

Pontiac, Michigan – General Motors reports that their heavy-duty trucks will receive a new Duramax turbodiesel engine and an all-new, first-in-class six-speed automatic for 2006.

The Allison 1000 transmission grows from a five-speed automatic to a six-speed for the Chevrolet Silverado and GMC Sierra heavy-duty trucks equipped with the Duramax 6600 6.6-litre V8 engine or the Vortec 8100 8.1-live V8. The transmission also features a tap-shift range selection function, which allows the driver to easily select the desired gears to match driving conditions, such as when towing a trailer on a steep grade.

The sixth gear, which is essentially a second overdrive gear, enables a 5.08:1 overall forward gear ratio coverage and allows the engine to operate at lower rpm, particularly during high-speed driving on the highway. Its 0.61-ratio sixth gear provides a 1550 rpm engine speed at 100 km/h, compared with the five-speed transmission’s 1800 rpm speed at 100 km/h.

The 2006 model year will also see a new 6.6-litre Duramax 6600 turbodiesel V8, rated 360 hp at 3200 rpm and 650 lb-ft of torque at 1600 rpm, which will be used in the Chevrolet Silverado and GMC Sierra HD models. In addition, all 2006 Duramax engines have been revised to deliver lower emissions and significantly improved quietness and smoothness.

The 2006 Silverado and Sierra HD models with the Allison six-speed automatic transmission will be equipped with a significantly revised, 310 hp Duramax 6600 throughout the third quarter of 2005. It will be replaced in these applications in the fourth quarter of 2005 by the new 360 hp version.

The new Duramax 6600 receives a strengthened iron cylinder block and lower compression ratio, along with a revised turbo capable of exhaust braking, and improved glow plugs that heat up faster through an independent controller.

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