Two weeks ago, Ford released horsepower and torque ratings for the new 2011 Super Duty trucks, claiming best-in-class numbers. Today Chevrolet announced the 2011 Silverado HD ratings, usurping the lead once claimed by Ford's Super Duty diesel.
The numbers on the new 6.6L Duramax (LML) diesel engine show it is the clear leader in diesel power: 397 hp at 3,000 rpm, and 765 lb-ft of torque at 1,600 rpm. Not only is the engine more powerful than its predecessor, but it is also more efficient. Chevrolet claims an 11-percent boost in fuel economy over the previous model. The updated engine is also cleaner, posting a 63-percent reduction in NOx emissions.
The engine has revised main bearing profiles to improve oil film thickness, increased oil flow for higher pressure at low speeds and updated turbocharger oil routing for faster oil delivery. A new piston design increases strength and connecting rod pin ends have been modified to increase piston support. The fuel injection system runs at 30,000 psi and is designed to be compatible with biodiesel fuel up to grade B20. Other enhancements include an exhaust gas recirculation (EGR) cooler bypass to reduce soot deposits in the cooler and EGR circuit.
Chevrolet also released numbers for the 6.0L V-8 gas engine, the standard engine offered in HD trucks. The gas engine is rated 360 horsepower at 5,400 rpm and 380 lb-ft torque at 4,200 rpm. The engine has improved idle over the previous model and 90 percent of its torque is available at 2,000 rpm.