GM Keeps It Simple to Boost Pickup Truck Performance

General Motors Co.'s redesigned fullsize pickups for 2014 reveal a powertrain strategy to boost performance and fuel economy while keeping the options simple.

The new Chevrolet Silverado truck will debut with two engine choices, each mated to a six-speed automatic transmission. A third powerplant a 6.2-liter V-8 variant of the engine used by the Chevrolet Corvette will be added later in the model year.

Debuting this year is a new 3.4-liter V-6 that makes 285 hp and 305 lb-ft of torque, compared with 195 hp and 297 lb-ft for the 4.8-liter V-8 it replaces. The optional 5.3-liter V-8 delivers 355 hp and 383 lb-ft of torque, up from 313 hp and 335 lb-ft for the 2013 engine.

Both new engines feature direct injection, cylinder deactivation and aluminum blocks with cast-in iron liners. Redesigned combustion chambers and pistons boost the compression ratio of each engine to 11:1 from about 9.9:1. Variable valve timing boosts efficiency.

The redesigned blocks for both engines incorporate a cam-driven, high-pressure fuel pump for the fuel injection system. Cylinder deactivation, which allow both engines to run on four cylinders during light-load conditions, is accomplished with a valve lifter that can be disabled by a hydraulically actuated sliding pin.

GM says the 5.3-liter V-8 has earned a government highway fuel economy rating of 23 mpg, making it the most fuel-efficient V-8 in its segment. Ratings for the other two engines have not been released.