2011 Chevrolet Silverado & GMC Sierra Heavy Duty Pickup Trucks
On the surface, the 2011 Silverado HD and 2011 GMC Sierra HD pickups are similar to their previous models, but redesigned grilles, full-width front bumpers and power dome hoods with louvers give both trucks a more powerful appearance. You'll find the most significant changes under the skin -- two improved engine/transmission combos, a completely redesigned frame, new front and rear suspensions and an improved brake system.
Silverado & Sierra HD Power Train
A 6.0 liter Vortec V8 gasoline engine is standard on both the Silverado and Sierra. Based on Chevys' small block design, the engine features a new camshaft profile that, when combined with the existing variable valve timing system, provides much better torque at low RPMs. While not yet rated, GM says the peak horsepower occurs at 4400 RPMs, but is at 90 percent of that at 2000 RPMs. That means pulling a trailer or taking off from a stop with a full load is easier and smoother.Power is transmitted through the 6L90 six-speed automatic transmission, which has strengthened input and output gear sets to stand up to the demands of the heavy duty truck. A very low first gear helps get the most out of the engine's torque when taking off from a stop. At the other end, both 5th and 6th gears are overdrive ratios to help improve fuel economy.
Six gears help the transmission and engine find the best combination to match the truck's load. Up-and-down shifts can be controlled manually with a tap up/tap down switch. Engage the tow/haul switch to let the computer alter the computer to match your towing requirements.
Optional on 2500 HD and 3500 HD trucks is the new 6.6 liter Duramax turbocharged diesel, which takes everything learned from its previous generation and adds current technology to create a more powerful, cleaner burning, more fuel efficient engine. Improvements include a selective catalytic after-treatment system that uses diesel exhaust fluid (DEF) to help reduce NOx emissions by at least 63-percent, higher pressure fuel injectors to aid in fuel economy and reduce emissions, an exhaust brake system that helps slow the truck and save wear on brake pads and B20 biodiesel capability. Torque and horsepower ratings as well as fuel consumption numbers haven't been released, but GM say all ratings should be an improvement over 2010 numbers.
The Duramax Diesel sends its power through a new Allison 1000 six-speed automatic transmission. GM strengthened the transmission to handle the increase in power and the subsequent higher tow rating. Engineers designed the internals to reduce slippage, which means more power to the rear wheels and better fuel economy.
Silverado & Sierra HD Frame and Suspension
GM's 2011 HD trucks both have a completely redesigned fully boxed frame built with additional high strength steel to greatly reduce twist and flex. The front section is hydroformed, which is much stronger and holds up better to snow plow use. To control the vibration and harshness that a stiff frame typically brings to the cab, GM has switched to larger engine and transmission mounts and, on Extended Cab and Crew Cab trucks, the cab is mounted on hydraulic mounts.The independent front suspension's upper and lower control arms have been strengthened to handle heavier loads. In previous trucks, one torsion bar spring rate was used in all models. Now there are five different bars with different spring rates to match the model and equipment. That means a truck with a snow plow package will not sag under the additional weight and a base model pickup won't have an overly stiff ride.
Rear suspension is handled by asymmetrical springs -- the axle is mounted forward of the center of the spring for better traction with less chance of wheel hop. The 2500 HD is equipped with two-stage springs, so when the truck is not loaded or lightly loaded, the ride is softer. When loaded, the second-step springs give extra support. 3500 HD trucks have a three-stage spring for for heavier loads.
Silverado & Sierra HD Steering and Brakes
To help handle the increased towing and load capacity, the trucks' steering and brakes were beefed up. The steering arms are larger, and the pump and steering gearbox are stronger with higher pressure. Larger brake discs, calipers and revised booster calibration all improve stopping power. Trucks with single rear wheels have 4 channel antilock brakes (ABS) and trucks with duel rear wheels have 3 channel ABS.
Silverado & Sierra HD Towing Abilities
All enhancements contribute to an increase in Silverado and Sierra towing capacity. Ratings vary depending on engine and cab/box configuration, as well as standard hitch vs. 5th wheel hitch, but can be as high as 20,000 pounds, with a payload up to 6,300 pounds.
Sierra HD Denali Option
Sierra HD buyers can choose the upscale Denali edition. It's available on the 2500 Crew Cab with a standard bed, and includes a body colored front bumper, a unique lower valance, leather seats, wood and brushed aluminum trim on the dash and doors and wood trim on the steering wheel. Heated and cooled seats are optional, and so is a heated steering wheel. This is the first time the Denali option has been available on a HD truck.May, 2010 Update: GMC has opted to add more models to its upscale lineup. Look for Denali packages on 2WD 2500 trucks and 2WD and 4WD Sierra 3500 crew cabs (single rear wheel and dually).