December 8, 2003


GM increases horsepower, torque of Duramax diesel engine

Pontiac, Michigan – General Motors announced its Duramax 6600 6.6 litre turbo-diesel V8 engine will offer higher horsepower and torque ratings and emission improvements beginning in January 2004.

Chevrolet Silverado and GMC Sierra 2500HD and 3500 Series trucks with the Duramax 6600 and the Allison automatic transmission will receive a new version of the engine with 310 horsepower @ 3100 rpm, 10 more horsepower than before. The engine also features a higher torque rating of 590 lb-ft @ 1600 rpm, a 70 lb-ft increase over its previous maximum high. At the same time, Duramax 6600 NOx emissions have been reduced almost by half.

“Since its introduction in 2001, the Duramax 6600 has re-established GM in the full-size diesel powered truck market by increasing our share of the segment to nearly 30 percent,” said Charlie Freese, executive director, diesel engineering for GM Powertrain.

Silverado and Sierra models with the Duramax 6600 and a standard ZF S6-650 six-speed manual transmission receive the same emissions improvements as those with the Allison 1000, with carryover power ratings.

“Over 90 percent of our three-quarter and one-ton customers order their Duramax 6600 with the Allison 1000 five-speed automatic transmission – prompting us to focus on power, torque and emissions improvements, where they provide greatest benefits for the largest number of customers,” Freese said.

Both the new version of the Duramax 6600 turbo diesel with the Allison automatic transmission and the version with the standard ZF six-speed manual feature improved hardware. The new version also has additional software calibration changes to help provide its higher power output.

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