General Motors’ recent launch of its 2014 Chevrolet Silverado and GMC Sierra full-sized pickup trucks has surprised competitors’ engineers who expected the new trucks to include more technology aimed at increasing fuel efficiency.
“They [the GM trucks] frankly shocked us when we learned they don’t at least have active grill shutters, something GM has been a leader in on passenger cars, or a greater focus on improved aerodynamics,” said a veteran Chrysler engineer who asked not to be identified, speaking with AEI at the 2013 Detroit auto show.
Also commenting on the GM pickups, a Ford program manager at the show observed: “While the current Ram 1500 clearly takes a big step toward the new CAFE regulations, bringing stop-start, the eight-speed transmission, grill shutters, and the Jeep air suspension for better high-speed aero, GM seems to have missed that memo.”
Compared with the Ram 1500, which won the 2013 North American Truck of the Year award based in part on its impressive fuel-saving-technology suite, the new Silverado and Sierra may appear understated in their approach to the oncoming 54.5-mpg CAFE target (actually about 32 real-world mpg for trucks, when the many credits are factored in). EPA fuel-economy testing for the trucks had not been completed as of mid-January.
They’re the most aero-efficient pickups in GM history, said Exterior Design Director Tom Peters, with Cd improved 5% compared with the current trucks and a moderate reduction in overall curb weight.
But their carryover six-speed automatic transmissions (GM is developing a new planetary eight-speed for RWD applications), and lacking the extensive list of fuel-saving equipment that Chrysler bestowed upon the MY13 Ram 1500, have caused initial industry reactions to be mild thus far. SOP and media launches are later this year.
Significantly lighter and stronger frame
The GM trucks are not a mid-cycle refresh but rather are all new, asserted the program's Executive Chief Engineer, Jeff Luke.
“With the new Ecotec3 V8 and V6 engines, there’s only a small bag of parts that carry over from today’s engines,” Luke told AEI during a background event last December. “The 4.3-L V6 gets a new aluminum cylinder block to save weight. The doors and cab are all redesigned, with the upper perimeter of the doors inlaid into the cab, which improves fit and NVH.”
The ladder frame is a significant upgrade, lighter by 20 kg (44 lb). GM engineers worked with their counterparts at frame supplier Magna to replace specific crossmembers with hydroformed high-strength steel members.
Front-end lateral modes have been improved, Luke explained, using stiffer bushings “that really help take the ride and handling to the next level,” complemented by electrically assisted rack-mounted power steering. Shear mounts are new to the cab, and the new Silverado and Sierra are the only 1500-series pickups engineered to accept a snow plow—a key differentiator, Luke asserted.
The most visible news is inside the cabs, which boast all-new interiors with improved control layout, 8-in color touch-screen display, heated cloth seats, and higher-quality surface finishes on all materials. “We added telescopic steering-wheel adjustment and brought in the Cadillac driver safety-alert seat as well as lane departure warning. And that’s only a short list of improvements,” Luke noted. See the full interiors story at http://www.sae.org/mags/aei/11652.
When asked if the GM pickups will beat the 2013 Ford and Ram V6 models in highway fuel economy (when the final EPA number is published), Luke said his team feels they’ll be “very competitive.”
Of the 2014 trucks’ new drive axles, the 9.5-in (241-mm) axle weighs 10.5 kg (23 lb) less than the incumbent 2013-model 9.5 axle, Luke noted. For V8 models, GM added a 9¾-in (248-mm) ring gear diameter.
New cab, front structure aim for meeting IIHS offset tests
The new cab is made of 66% high-strength steel overall. The materials are incorporated in the A- and B-pillars, roof rails, and rocker panels. Ultra-high-strength alloys are used in “tailored” fashion in the rocker panels and cab underbody in anticipation of the Insurance Institute for Highway Safety’s new shallow-offset (also called small-overlap) frontal crash tests introduced in 2012.
The test, conducted at 40 mph (64 km/h), replicates the results of a collision in which the vehicle’s front corner collides with a tree, utility pole, or another vehicle—a 5 ft (1.5 m) tall rigid barrier in the test. Twenty-five percent of the total width of the vehicle strikes the barrier on the driver side, on which 16 interior and exterior points are measured for the amount and pattern of intrusion.
“We’re working closely with the IIHS to understand their testing protocol for this,” Luke said. “Our new front-end structure gives us something we can work with for this."
Besides the new aluminum cylinder block on the 4.3-L V6, the engine portfolio including 5.3- and 6.2-L Ecotec3 V8s shares new Delphi direct fuel injection, continuously variable valve timing, and cylinder deactivation technologies (see http://www.nxtbook.com/nxtbooks/sae/13AEID0115/index.php#/0).
Forged aluminum also makes its way into the upper front control arms and cast aluminum lower control arms and steering knuckles of 4wd crew-cab models for a 42-lb (19-kg) mass reduction. The aluminum inner and outer hood panels save 17 lb (7.7 kg) over a comparable steel panel.
Final validation and testing of the 2014 Silverado and Sierra continue as part of the more than 13 million mile (nearly 21 million km) vehicle testing program.