SANTA BARBARA, CA – Sure, the launch of all-new fullsize half-ton Chevrolet and GMC pickups is a big deal for General Motors, especially as truck sales are rebounding.

But equally significant is the availability of three new pushrod engines, all of them carrying forward the steadfast traits of GM’s heralded small-block engine family, now in its fifth generation.

After driving ’14 GMC Sierra 1500 pickups here powered by both the 4.3L V-6 and the high-volume 5.3L V-8, it is safe to declare the future of the small block – and overhead-valve engine architectures once thought to be outdated – as bright as when this powertrain masterpiece first arrived in 1955.

This evaluation centers on the Sierra 1500 crew cab with the 5.3L and uplevel SLT trim, sticker-priced at a brow-raising $50,855 and very well equipped.

The take-rate for the new 5.3L V-8 is expected to exceed 70%, and it’s easy to see why.

Towing a 23-ft. (7-m) Airstream camper weighing 5,500 lbs. (2,494 kg) through a series of maneuvers on a Camarillo airstrip north of Los Angeles, the 5.3L V-8 bats away duty requests with steely confidence and even a bit of haughty derision.

Start at wide-open throttle in 2-wheel-high mode, and the rear tires squeal with glee as the sizable rig lurches forward and reaches 30 mph (48 km/h) in a matter of seconds.

An emergency stop fails to upset the apple cart, a testament to the outstanding stability that augments the world-class EcoTec3 powertrain.

Maneuverability with the trailer attached is excellent at any speed, even while creeping on Highway 101 past an accident involving a side-swiped police cruiser and a massive semi-trailer that had tipped over into a ditch.

Breaking through that logjam, the 5.3L stretches its legs but continues to feel as if it is barely breaking a sweat, achieving most of its work below a moderate 2,000 rpm.

The only challenge with this portion of the drive is heeding the warning that the California Highway Patrol writes tickets when personal trailers are towed faster than 55 mph (89 km/h).

Even at higher speeds, the 5.3L (code name L83) struts its stuff by conquering several uphill grades with only half its cylinders doing the work.

Active Fuel Management, GM’s brand name for cylinder deactivation, has been improved to the point that “V-4” mode flashes in the instrument cluster much of the time, even while towing.

Think you can tell when the engine transitions between 8-cyl. and 4-cyl. modes? Forget about it. And don’t mistake gear shifts on uphill grades for the AFM system kicking in.

Cylinder deactivation, tied together with direct fuel injection and all-aluminum construction for the first time on all small blocks, is an important component in GM’s strategy to keep pickup trucks in the market without having to pay steep penalties to meet impending fuel-economy standards.

With no trailer, the Sierra 1500 makes the 58-mile (93-km) trip from Los Angeles to Camarillo while achieving an acceptable 20.1 mpg (11.7 L/100 km), in line with the 4-wheel-drive fuel-economy rating of 16/22 mpg (14.7-10.7 L/100 km) city/highway.

With trailer attached, the Sierra’s 5.3L V-8 manages the 62-mile (100-km) drive from Camarillo to the Ocean Mesa campground near here while logging an impressive 12 mpg (19.6 L/100 km) – and that factors in the 30-minute traffic mess on the 101.

Along the way, the 355-hp 5.3L is amazingly quiet, smooth and composed. While idling at stoplights, many owners will assume the truck has stop/start, but it doesn’t. Not yet, at least.

Ford has achieved great success by selling its 3.5L EcoBoost V-6 in the F-150 as an ostensible replacement for the 5.0L V-8.

But GM makes a compelling argument that its 5.3L makes better sense, carrying an $895 premium over the V-6 on the Sierra SLE trim.

Meanwhile, Ford’s EcoBoost V-6 is more expensive than its own 5.0L V-8 and costs an extra $2,100 on the F-150 XLT over the standard 3.7L V-6. However, Ford will be quick to note the EcoBoost V-6 makes more horsepower and torque than GM’s new V-8.

Not to be overlooked is the all-new 4.3L V-6, which moves the 4,900-lb. (2,222-kg) crew-cab Sierra with ease.

The Airstream was not hitched up for the V-6 evaluation, but others who have towed sizable loads with the engine (code name LV3) say it easily could be mistaken for the V-8.

The new 4.3L V-6 is derived from the V-8, making it a chip off the ol’ small block, literally, with two fewer cylinders.

Content is shared between the two engines, and they are manufactured on the same line in Tonawanda, NY, allowing easy adjustments depending on demand swings.

As fuel-economy mandates loom, auto makers will continue improving V-6s to the point they will meet the needs of most pickup customers.

Case in point is the Ram 1500. Its 3.6L Pentastar V-6 recently earned a Ward’s 10 Best Engines trophy.

GM offered two V-6s in its previous-generation pickups, and neither was noteworthy. As the new trucks roll out, the auto maker expects V-6 take-rates to more than double, well beyond 20%.

In real-world driving, the pushrod 285-hp V-6 isn’t too shabby, logging 19 mpg (12.3 L/100 km) during a spirited 70-mile (113 km) jaunt around Santa Barbara.

And unlike Chrysler’s Pentastar, GM’s new 4.3L shuts down two of the six cylinders during light loads to save fuel. The Ram’s Pentastar is offered with an optional stop/start system.

GM claims all three available engines deliver best-in-class towing capability: 7,200 lbs. (3,265 kg) for the V-6; 11,500 lbs. (5,216 kg) for the 5.3L V-8; and 12,000 lbs. (5,443 kg) for the 6.2L small-block V-8 that will be available this fall.

As for the rest of the Sierra, it’s a solid truck, with a comfortable and spacious interior and “professional grade” amenities, such as real aluminum on the dashboard and steering wheel of most models.

A large central display screen on the uplevel SLT trim allows access to navigation and other vehicle systems, as well as simple connections to cellular phones.

And five USB ports are supposed to allow multiple devices to work in tandem with the audio system. However, only one port would work during our evaluation, and the system failed to recognize two separate iPods.

Exterior styling evolves ever slightly from the previous truck, with squarish fender flares that are more pronounced.

The front end looks more aggressive, thanks to jeweled headlamps. On the upscale Denali model, grille perforations resemble a brick wall.

GM used to have five plants assembling pickups and now has three (Silao, Mexico; Flint, MI; and Fort Wayne, IN), improving capacity utilization and profitability.

Sierra crew cabs are shipping to dealers now, while double cabs arrive in July and regular cabs arrive a month later.

It’s ironic that the Sierra’s heart and soul is its small-block, because this compact engine is massive in its capability.

tmurphy@wardsauto.com

'14 GMC Sierra 1500 SLT
Vehicle type Fullsize crew-cab 5- or 6-passenger pickup with 4-wheel drive
Engine 5.3L OHV all-aluminum V-8 with direct injection and 2 valves per cylinder
Power (SAE net) 355 hp @ 5,600 rpm
Torque 383 lb.-ft. (519 Nm) at 4,100 rpm
Bore x stroke (mm) 96 x 92
Compression ratio 11.0:1
Transmission 6-speed automatic
Wheelbase 153 ins. (389 cm)
Overall length 239 ins. (607 cm)
Overall width 80 ins. (203 cm)
Overall height 73.8 ins. (188 cm)
Curb weight 5,292 lbs. (2,400 kg)
Base price $43,425 ($50,855 as tested)
Fuel economy 16/22 mpg (14.7-10.7 L/100 km)
Competition Ford F-150, Ram 1500, Toyota Tundra, Nissan Titan
Pros Cons
Trailers Airstream with confidence California limits towing to 55 mph
Small-block endures test of time Must wait for 6.2L small block
Upscale new interior Questionable USB access