New Duramax 6.6L diesel introduced on 2017 Sierra HD and 2017 Silverado HD.

The next-generation Duramax 6.6L V-8 turbo-diesel offered on the 2017 Sierra HD and Silverado HD boasts more horsepower and torque than ever — an SAE-certified 445 horsepower, and 910 lb.-ft of torque, 90 percent of which kicks in at a low 1,550 rpm and sustains it through 2,850 rpm.

Along with a 19 percent increase in max torque over the current Duramax 6.6L, the redesigned turbo-diesel’s performance is quieter and smoother. GM says the new engine’s noise at idle is reduced 38 percent.

“Nearly everything about the Duramax is new, designed to produce more torque at lower rpm and more confidence when trailering or hauling,” said Gary Arvan, chief engineer. “You’ll also notice the refinement improvements the moment you start the engine, and appreciate them as you cruise quietly down the highway — with or without a trailer.”