Chevy introduced the facelifted 2011 Chevrolet Silverado Heavy-Duty at the Chicago Auto Show last month revealing the 6.6-liter Duramax engine but giving very few details of its performance figures. However, GM has now proudly announced that the 2011 Chevrolet Silverado 2500HD and 3500HD will deliver the segment’s best diesel torque and horsepower.

According to Chevrolet , the revised Duramax turbo-diesel V-8 engine available on the 2011 Silverado 2500HD and 3500HD models, will be rated at 335 horsepower (249 kW) at 3,100 rpm and 685 lb-ft of torque (928 Nm) at 1,600 rpm.

“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.”

The powerful engine now offers improved fuel economy reducing the NOx emissions by up to 63 percent. This combines with 36-gallon (136 L) fuel tank to provide up to 680 miles (1,090 km) of highway driving between fill-ups. Silverado 3500HD now gets a fifth wheel hitch increasing its load capacity to  20,000 pounds (9,072 kg).

A number of other enhanced features like the increased oil pump flow, revised turbocharger oil circuit, higher-strength piston design, new 30,000-psi (2,000 bar) piezo-actuated fuel injection system and EGR cooler bypass add to the 2011 6.6L Duramax turbo diesel’s power performance.

Chevrolet also announces the standard Vortec 6.0L small-block V-8  engine in Silverado HD trucks has now been re-engineered ideally to deliver  360 horsepower (268 kW) at 5,400 rpm and 380 lb-ft (515 Nm) at 4,200 rpm in Silverado 2500HD and 3500HD pickup models.