Rarely do vehicle categories enjoy a century of evolution in becoming a customer favorite. Such is the luck for today’s full-size pickups.
The alignment of American culture and the pickup truck only accentuates the engineering challenges lying ahead. Half-ton pickups are expected to provide the passenger comfort of the best mainstream sedans without relinquishing their appetite for hard work. Such attributes have made them the industry’s cash cows, capable (along with their full-size SUV brethren) of earning $10,000/unit margins. Ironically, pickup sales revenues are key to funding R&D for the Detroit-3’s electric and connected/autonomous vehicle programs.
Heading into the 2020s, the trick for OEMs is to maintain pickup affordability while making significant leaps in vehicle efficiency. For the 2021 model year, U.S. national standards require light trucks to average roughly 33 mpg, a gain of more than 6% from model year 2020, according to the NHTSA. Meeting ever-tightening future regulations, even if those pending for 2022-2025 are relaxed, will require a careful ascent of the technology cost/benefit ladder.
Engine stop-start, cylinder deactivation, engine downsizing/boosting, and 8- and 10-speed transmissions are solutions well underway. Light-weighting—the truck segment’s universal efficiency strategy—calls for higher-cost metal alloys, tailored blanks, structural composites, and a new wave of joining technologies to enable their mixed use in vehicle assembly. The next rung on the truck-tech ladder—mild-hybrid 48-V systems and new diesel engines arriving in 2019—is expected to push some models past the magic (for trucks) 30-mpg threshold, albeit with a price premium.
Ford, Ram and GM engineers are confident their most optimized F-150, Ram 1500 and Silverado/Sierra models will meet requirements—even as they load the trucks with more compelling features and heightened capabilities.
Ford F-150 gets a diesel
The ruler of the roost is the U.S. market’s top nameplate for the past 36 years. Give Ford credit for helping buyers break the V8 habit with its 2.7- and 3.5-L EcoBoost V6s. The use of downsized-and-boosted engines in this test-weight class are enabled by Ford’s pioneering aluminum-intensive bodies, which slashed the F-150’s curb weight by up to 700 lb (317 kg) at the time of the truck’s MY2015 overhaul.
For 2018, Ford adds both a 3.3-L gasoline V6 and a 3.0-L turbodiesel V6. The latter, based on the ‘Lion’ engine family, is manufactured by Ford U.K. It’s the enabler for certifying F-150 at 30-mpg or more. (EPA testing had not been completed at press time.) The engine was designed and engineered by the Ford team that developed the 6.7-L V8 diesel used in HD pickups, according to Dave Filipe, Vice President of Global Powertrain Engineering.
To be paired with the 10R80 10-speed automatic, the ‘Power Stroke’ V6’s basic architecture is similar to that used on the 2.7-L—a compacted-graphite iron cylinder block and aluminum DOHC heads. Bore and stroke dimensions are undersquare at 84 x 90 mm. Felipe noted that for truck duty, the forged-steel crank gets a new heat treatment and upgraded material for the rod and main bearings.
The diesel runs a 16:1 compression ratio. To mitigate turbo lag, Ford engineers spec’d variable-geometry Honeywell turbocharger, air-to-air intercooled. Effective boost pressure ranges from 7 psi (.48 bar) steady-state to 20 psi (1.4 bar) at full load, Felipe noted. Siemens piezo-type fuel injectors operating at 29,000 psi (2000 bar) help reduce engine-out emissions and noise.
A mechanical viscous-controlled cooling fan was chosen over electric fans due to its greater capacity under heavy-load towing conditions, explained lead engineer David Ives. Under moderate load, the viscous unit via solenoid closes two radiator shutters for improved aerodynamic efficiency. A two-stage ‘smart’ oil pump reduces internal parasitics.
The engine is SAE-rated at 250 hp (186 kW) and 440 lb·ft (596 N·m), with peak torque arriving at 1750 rpm. Diesel F-150s will offer SAE J2807-certified 11,400 lb (5171 kg) towing capacity. According to Felipe, Ford estimates 5% of F-150 buyers—about 32,000 units of production—will check the $4000 diesel option in the first full model year. The F-150-based Ford Expedition and Lincoln Navigator also would be worthy applications for the Power Stroke 3.0.
Chevrolet 2019 Silverado adds diesel, sheds mass
The new Silverado won’t reach customers until late this year, but GM had two reasons for rushing the fourth-generation truck to the stage: in 2017, Ram sales closed within 86,000 units of Chevy’s crown prince and an all-new tech-laden Ram bowed at the 2018 Detroit show. GM had nothing to gain by letting FCA hog that limelight.
Given Silverado advertising’s merciless attack of the F-150 bed floor’s vulnerability to punctures, there was no way Chevy could follow Ford’s deep commitment to aluminum structures. Instead, GM adopted a mixed-materials strategy with aluminum, steel, and composites assigned according to each application’s specific needs. The Silverado’s fully boxed ladder frame, for example consists of hydroformed, roll-formed, and tailor-gauged stamped steel. Some 80% of that structure is made of high-strength steel with sections, grades, and gauges selected to trim 88 lb (40 kg) from the outgoing frame while also increasing torsional stiffness by a claimed 10%.
While the new Silverado is slightly larger in most dimensions it is up to 450 lb (204 kg) lighter than a comparable 2018 model. The 3.9-in (99-mm) wheelbase stretch, 1.6-in (40-mm) increase in overall length, and 1.0-in (25.4-mm) increase in height provide worthwhile gains in interior space, especially in the rear seat.
Roll-formed steel is retained for the bed floor but its yield strength is significantly increased from 340 to 500 MPa (49,313 to 72,519 psi) for greater resistance to dents and punctures caused by rocks, sharp objects, and animal hooves. In a showcase of mixed-material lightweighting, the cab consists of seven grades of steel stampings while the hood, tailgate outer, and doors are pressed aluminum weldments to trim body weight by another 88 lb. Front suspension control arms are forged aluminum. A composite-plastic second-stage leaf spring replaces a steel component in LT models, dropping 24 lb (11 kg).
The Silverado’s 2019 GMC Sierra cousin adds an optional carbon-fiber-composite cargo box, developed by GM and Continental Structural Plastics. The lightweight bed offers dent, scratch and corrosion resistance, according to Tim Herrick, the Sierra’s chief engineer. Compared to the standard steel truck bed, the carbon fiber bed is 62 lb (28 kg) lighter. Because of the material’s formability, the sides of the carbon fiber box are pushed further outward--increasing the volume by a cubic foot.
Designed into the new bodywork are aerodynamic improvements. Adaptive curtains are integrated into the Silverado’s grille to deflect air around the wheel wells during cruising. Spoilers built into the trailing edge of the roof and the top of the tailgate also contribute to a 7% reduction in aerodynamic drag.
In 2015 GM invested $263 million in its Flint, MI, engine plant to tool a new 3.0-L inline six-cylinder turbodiesel for light truck applications. Destined first for the 2019 Silverado, the new diesel is claimed by GM North America President Mark Reuss to outperform its Ford and Ram counterparts. While GM has yet to announce further 3.0-L details beyond stop-start (itself a first for Silverado), a CGI block with aluminum DOHC head, variable-geometry turbo and cooled EGR are likely technology candidates for durability, mass efficiency and emissions performance.
The Hydra-Matic 10L80 10-speed automatic developed in collaboration with Ford will pair with both the new diesel and 6.2-L gasoline V8. The latter, along with its 5.3-L cousin, feature the first production application of Dynamic Skip Fire (DSF) cylinder shut-down technology, based on proprietary algorithms developed by Tula Technologies. The subject of various SAE Technical Papers, the DSF (which GM calls Dynamic Fuel Management) is the industry’s first fully-variable digital cylinder deactivation technology. It has been refined to the point where, in GM’s small block V8, it enables the vehicle to creep ahead in traffic while operating on a single cylinder.
Tula claims a V8 equipped with DSF san deliver up to 15% reduction in CO2 emissions, mainly in light-load/steady-state operation.
The 2019 Ram 1500
Coded DT, the Ram 1500 carries over only its cargo box floor from 2018. The new truck is bigger but lighter, more fuel efficient, brawnier, more comfortable, safer—and has arguably gained an edge in technical sophistication over its Ford and GM rivals. The ‘19 Ram brings the first production use of a 48-V mild hybrid system in a North American pickup, and a rear differential heater/cooler that enables the use of low-friction lubes. FCA boss Sergio Marchionne has publicly stated that Ram is so crucial to his enterprise’s profitability that two sedans were discontinued to fund this pickup’s design and development.
Stretching Ram wheelbases by 4 in (102 mm) and overall length by nearly 10 in (254 mm) enabled a 4-in increase in cabin length. The all-new frame, supplied by Metalsa, is 98% high-strength steel with two aluminum crossmembers. As a result it is 100 lb (45 kg) lighter than its predecessor. The side rails, rated at 110 ksi, are taller than those on the 2018 frame. Design highlights include patented mandrel-formed, octagonal front rails with tailored-gauge walls that splay outward ahead of the front tires to absorb energy during offset frontal impacts. Active Tuned mass dampers attached to the frame quell NVH and enable extended 4-cylinder mode during V8 cylinder deactivation.
Payload of the half-ton pickup has been increased by 420 lb (190 kg) to 2300 lb (1043 kg) and the maximum tow rating is up 2050 lb (930 kg), to 12,700 lb (5760 kg). That’s less than F-150 but tops GM, Nissan, and Toyota.
No stranger to aluminum, FCA engineers also converted Ram’s tailgate, engine mounts, front axle center housing and steering gear to the light alloy, to help trim 225 lb (102 kg) from its curb weight. Front suspension control arms are a composite of reinforced nylon shot molded over steel for added strength, according to Ram Vehicle LIne Executive Rob Wichman.
The new cab’s door aperature ring is now hot stamped in ultra-high-strength steel alloy, with hydroformed front ‘shotguns.’ Its D-pillar is hydroformed as a continuous piece, saving 7 lb (3.1 lb). Fenders, doors, and roof panels are made of bake-hardening steel while the bed floor is high-strength, low-alloy steel. The hood, which was already aluminum, was optimized using FEA, resulting in a further 10-lb (4.5-kg) reduction.
The active-deploying front splitter, developed in collaboration with Magna, is composite (see related article in Tech Briefs section). The shape of the hood and lips at the trailing edge of the roof and atop the tailgate optimize airflow. The top edges of the box are raised 1.5 in (38 mm) and the cab-to-bed gaps were tuned to diminish turbulence.
The body changes, combined with active grill shutters and the optional Continental-supplied air suspension’s Aero mode that lowers the truck at highway speed, help 4x2 Quad Cab models achieve a .357 Cd—a 9% improvement over 2018.
Every ounce counts in the efficiency war. Six pounds (2.7 kg) were trimmed by switching from an engine-driven hydraulic pump to electric assist for the rack-and-pinion power steering, while improving fuel economy by a claimed 1.8%. Converting the parking brake to electric actuation saved another 20 lb (9 kg). Wichman noted that use of pulse-width modulation in the electrical system reduced fuel pump and cooling fan loads, improving fuel efficiency by 0.4%.
Two 48-V hybrid systems
Three powertrains are offered for 2019, but the big news is FCA’s implementation of two 48-V mild hybrid systems for Ram, paralleling the technology’s debut on Jeep Wrangler and Cherokee. Rams use a belt-driven motor generator, a 3-kW DC-DC inverter, and a .43 kW·h, 12-cell, LG Chem lithium battery. The hybrid systems start the ICE in .55 s after an auto stop, supplement engine torque at times and capture energy during deceleration. A conventional starter is still fitted.
According to Mike Duhane, Global Director of Powertrain Electrification, there are two distinct eTorque systems. A 9-kW liquid cooled version supplied by Continental is standard on the 3.6-L V6 and delivers 90 lb·ft (122 N·m) of launch torque. A 12-kW air-cooled unit sourced from Magneti-Marelli is optional on the 5.7-L Hemi V8; it offers 130 lb·ft (176 N·m).
FCA’s 3.0-L turbo-diesel V6 is expected to join the Ram 1500 flock in 2019 and a U.S.-made 2.0-L turbo 4-cylinder gasoline engine, likely with e-Torque, will also be added.
Cresting the 30-mpg barrier is only the first step for half-ton pickups. Further light-weighting, advanced powertrains and even vehicle downsizing efforts will be required as the efficiency crusade continues, experts say. 40 mpg? Ford has announced a hybrid F-150 for 2020 and is also testing the radical opposed-piston gas and diesel engines under development by Achates Power. And Tesla CEO Elon Musk claims to be preparing a battery-electric design.
Musk recently tweeted, “I promise that we will make a pickup right after Model Y (small crossover). Have had the core design/engineering elements in my mind for almost five years. Am dying to build it.”
—With supplemental reporting by Lindsay BrookeContinue reading »