Firmly focused on fuel economy, General Motors has announced that all of its 2010 Chevrolet and GMC V-8 powered trucks now feature variable valve timing (VVT). The addition of VVT to the 4.8- and 5.3-L truck V-8s completes the OEM’s truck small block V-8 lineup, which also includes 6.0- and 6.2-L engines.
VVT technology, GM notes, enables continuous control of valve opening and closing, which results in better engine breathing, fewer emissions and improved fuel economy. The component that makes VVT possible is a cam phaser attached to the end of the camshaft that electro-hydraulically controls cam position with the help of a sensor and the engine control module.
General Motors also announced recently that powertrain enhancements have enabled its Chevrolet Silverado and GMC Sierra pickups to achieve improved fuel economy. Contributing to this development, for example, is a new fuel saver mode that enables the trucks to make better use of GM’s Active Fuel Management system and run on four cylinders in light throttle conditions instead of eight. Additionally, more efficient six-speed transmission shift points and a lower gear ratio of 3.08 (now standard on full-size pickups) also play a role in improving fuel economy.
GM is also quick to point out that fuel economy improvement comes without compromising horsepower, payload or trailering capability. For 2010, GMC Sierra and Chevrolet Silverado heavy-duty trucks are offered in 2500HD (three-quarter-ton) and 3500HD (one-ton) models. Configurations available include three cab styles, three cargo box styles and five wheelbase lengths.
The 2010 Sierra HD and Silverado HD pickups have an 18,500-lb. gross combined vehicle weight rating for models with a gasoline powered V-8 and a 13,000-lb. conventional trailer weight rating enabled by a larger-capacity trailer hitch platform. Maximum towing capacity is 16,500 lbs. on the Sierra and 16,700 lbs. on the Silverado when equipped with a fifth-wheel hitch.
GMC continues it hybrid truck offerings in 2010 with the GMC Sierra hybrid and Chevrolet Silverado hybrid full-size pickups. Driven by General Motors’ patented two-mode hybrid system and a 6.0-L gasoline V-8, according to the OEM, the hybrids can achieve 40% greater city fuel economy and a 25% improvement in overall fuel economy compared to non-hybrid models. EPA-estimated fuel economy for both 2WD and 4WD models is 21 MPG city and 22 MPG highway. With a 26-gal. fuel tank, the hybrids’ cruising range is more than 500 miles.
The GM hybrid models’ fuel-saving performance, the company says, is derived from an electrically variable transmission (EVT) and a 300-volt nickel-metal hydride energy storage system (ESS), which work with the standard 6.0-L V-8 gasoline engine with active fuel management (AFM) and late intake valve closing (LIVC) technology. The hybrid system enables the vehicle’s V-8 engine to operate in its more economical V-4 mode for longer periods.
In the GM hybrids, the system generates electricity used to propel the vehicle. When the brakes are applied or the vehicle is coasting, the electric motors within the hybrid system generate electricity that is stored in the 300-volt battery. This stored energy moves the vehicle and the regenerative braking cycle is renewed. This saves fuel by allowing the vehicle to launch and drive up to 30 MPH on electricity alone, even when towing a trailer. Towing capacity on the hybrids is 6,100 lbs. in 2WD models and 5,900 lbs. in 4WD versions.
Along with a full range of vehicles, GM is working to better serve its fleet customers. Recently, General Motors Fleet and Commercial Operations appointed 24 fleet field professionals to focus on helping state, city and municipal customers meet their fleet needs. GM Fleet and Commercial Operations also offers specification and ordering tools, fuel economy calculators, information in financing alternatives and a wide variety of service programs. For more information on GM’s fleet and commercial vehicle and service offerings, visit www.gmfleet.com.
