Advanced new EcoTec3 engines
Sierra’s engine portfolio is updated for 2014 with the goal of increased in power, torque and fuel efficiency across the board. There will be a 4.3L V-6, a 5.3L V-8 and a 6.2L V-8 offered, all from a shared EcoTec3 engine family. Each engine features standard direct injection, continuously variable valve timing and Active Fuel Management, which means they seamlessly switch to run on four cylinders during light-load driving to save fuel.
The increased power and efficiency of the new engines are the result of more than 10 million hours of sophisticated computer modeling, more than half of which were used to make the best of the combustion process.
Sierra’s new 5.3L Ecotec3 delivers the best V-8 pickup fuel economy in the industry. Benefiting from direct injection, cylinder deactivation and variable valve timing, the engine achieves EPA estimates of 16 mpg city and 23 highway with two-wheel drive or 16/22 with four-wheel drive.
In addition to highway estimates that are 2 mpg higher than a comparable 2013 Ford V8 pickup and 3 mpg higher than a Ram V8, Sierra’s new V-8 fuel economy estimates also measure higher than those of the 2013 Ford F-150 EcoBoost V-6.
The new 5.3L EcoTec3 V-8 combines its leading fuel efficiency with performance and capability. With an SAE certified 355 hp and 383 lb-ft of torque – increases of 40 hp and 48 lb-ft compared to the 2013 model – Sierra’s new 5.3L offers a class-leading towing capacity of up to 11,500 pounds.
A standard 4.3L V-6 EcoTec3 engine has the most torque of any standard V-6 in the segment – 305 lb-ft (413 Nm) and trailering ratings up to 7,200 pounds (3,266 kg) for a regular cab, short bed, four-wheel-drive model – 500 pounds more than the most capable Ford F-150 3.7L and 700 pounds more than a Ram 1500 3.6L. Sierra’s standard V-6 produces an SAE-certified 285 horsepower (212 kW) and is matched with a proven, efficient six-speed automatic transmission. EPA fuel economy estimates will be released later.
“Rather than adapting a V-6 intended for use in passenger cars, we built a new engine from the ground up based on the unique demands of a truck,” said Jordan Lee, powertrain chief engineer. “Sierra’s 4.3L shares its basic design architecture with the latest iterations of the V-8 engines that GMC owners have trusted for generations.”
Jordan Lee, powertrain chief engineer
With the new engine designs and additional developments, customers should expect Sierra’s second-generation Active Fuel Management to be more seamless and capable of operating longer in four-cylinder mode.
All three engines use lightweight aluminum blocks and heads and are mated with durable six-speed automatic transmissions. A “cruise grade braking” feature down-shifts the transmission on downgrades, which is intended to reduce brake wear. V-8 models use new, larger 9.5- and 9.76-inch rear axles with the strength to accommodate the engines’ higher output. Final power and torque ratings will be announced later for 4.3L and 6.2L models.