March 7th, 2019
Heavy Duty trucks mirror the contest for market domination in light duty trucks. This year both GM and Ford announced significant upgrades to the engines powering their all new 2500 and 3500 HD trucks as each company upgraded their diesel engine, and delivered new gas engines.
At GM, the launch event centered on Chevrolet, who brought in truck writers from every segment—popular to fleet management—to Flint, Michigan’s Flint Truck Plant. Flint is the original home of General Motors trucks and the spiritual and historical home of the UAW. So, Flint Truck Plant is receiving an all-new facility constructed and designed for just HD trucks, with the former truck assembly areas destined for warehousing and future projects.
New L8T 6.6-Liter Gas Engine
We first spoke to Mike Kociba, a GM engineer and part of the Small Block team to learn about the new 6.6-liter V-8 engine we'd been anticipating.
Mike told us the new motor “is a marriage of the six-liter it replaces and an upgrade in technology levels to Gen 5 architecture.” A careful look will disclose similarities in key areas where GM has maximized their experience with the six-liter’s durability and improvements in performance levels derived from Gen 5 architecture. “Specifically, new here is the gray cast-iron block which is unique for this application, hyper-eutectic purpose-built pistons for this application and heavy-duty requirements, forged powdered-metal connecting rods, and a forged steel crankshaft,” Mike continued.
The most significant change is the addition of Direct Injection. It’s all new, an industry first for the heavy-duty market and new to GM trucks. “When we added DI, we took the roughly 400 KPa fuel pressure from the low-pressure pump and dialed it up to roughly about 15 mPa for engine operation under key conditions,” Mike continued. “That allows us to increase compression ratio, now 10.8:1 using regular fuel. Without DI you're not going to hit those numbers without losing a lot of spark efficiency. With those additions, and the six millimeter longer stroke, that gets us up to 6.6-liters.”
“That suite of changes allows us to hit class-leading gasoline engine torque, at 464 foot-pounds at a lower engine speed than the outgoing six-liter was optimized for. I'm proud of its 401 horsepower, which is SAE Certified, no games, legitimate. This (engine) is purpose-built to crank out those numbers day, after day, after day with no compromise in durability. Customers can have confidence they're going to pull, tow whatever trailer you need.”
There are other new features like an all-new water pump and a massive cooling fan to meet the demands of the HD customer base. New is how the water pump drives the fan through a one-inch shaft using purpose-built bearings to handle loads.
Another first for HD is a variable-output oil pump. “No mater what the severe operating condition is for the customer, the pump is capable of dialing in more, or less oil pressure regardless the requirement.
The engine features an aluminum oil pan, nylon 6-6 air intake, and stainless steel exhaust manifolds unique for the Heavy Duty market. That’s because HD market has specific requirements for (fuel) enrichment and these stainless manifolds will meet those requirements. “We have variable dual-equal valve actuation, like on light duty, where intake and exhaust are phased together and controlled through the actuator on the front cover. It's chain driven for accessories.” GM designed this engine specifically for upcoming standards for particulates and NOx emissions standards. “With this architecture we're not just making power and torque, but improved emissions and improved efficiency.” Mike continued.
We noted the massive valves, which Mike said are common with Gen 5 architecture for valve layout and their pushrod technology. “That's how we get this compact shape. When you compare the size of the two engines, they're similar, which is due to the common 4.4-inch bore spacing.”
A unique feature of the new engine is inter-bore cooling. Coolant flows between the Siamesed bores, notably in the upper bores where there’s a tendency to generate higher temperatures.
“For two-valve technology of course you've got the spark plug, and the fuel injector, splayed outside. To avoid heat, we have the coil mounted directly on the rocker cover and the boot mounted next to the manifold with industry-standard individual coils for each cylinder.”
This is great stuff, we though, but engine development isn’t cheap. So, why a new 6.6-liter when the 6-liter was doing well?
“We needed to improve to Gen 5 level of technology to be sure (the engine) is capable of delivering on durability requirements. Customers love the convenience of gas, but if you look at the market—for instance trailers with more gadgets and slide-outs—everything is getting heavier. Customers want to be sure they can tow with confidence, no compromises, whether it's fuel economy, power, torque, emissions, efficiency, they don't want to pull up to their neighbor and have to make excuses.
That's what we targeted. No compromises. With the significant technology we put into this engine, it makes segment-leading torque without compromising efficiency or emissions. Peak torque is at 4,000 rpm, 400 rpm lower than the 6.0-liter. Three things enable the new 6.6-liter's better power output. Direct injection (DI) allows us a higher compression ratio; longer stroke is good for increased torque (but not as good for horsepower as piston speeds are high) and for heavy-duty application where you need torque everywhere it’s why we focused on a longer stroke to get to 6.6-liter displacement. Those changes enabled us to broaden the torque curve, which is up 20% everywhere, for greater work potential.”
We thanked Mike and asked if we’d missed anything. “Small engines with turbochargers allow them peak torque off idle, but for heavy duty we don't want that complexity. For the Heavy Duty segment we (General Motors) have durability requirements—Global Engine Durability—that are unique and very long and stringent requirements. We know customers need 401 horsepower and 464 lb.-ft. of torque today, tomorrow, and every day for years to come with no compromise in durability.
We know our customers and, if they can't use their truck today, they might not get paid. That's why we focus on durability.”
Brand New HD 6-Speed Transmission
With that in mind, we next spoke to the systems chief engineer for six-speed FWD and RWD transmissions Rich Mardeusz. More power and more torque tend to break an older transmission. So, we wanted to know what changes had been made to the new transmission to carry the additional torque.
“We started with the 6L90 that's in the current HD vehicles and full-sized vans (and ZL-1 Camaro and CTS-V), received the horsepower and torque curves from the engine engineering teams and then performed an analysis of all mechanical components from front to back,” Rich said. General Motors uses specific simulation tools for different parts. “For instance, we have a "gear damage analysis tool" for analyzing the gear set and how much damage it may receive over the life of the vehicle,” Rich told us. The result was a need to improve the torque converter and the clutch pack, which needed to be more robust to accommodate the greater power output of the upgraded 6.6-liter V-8 engine.
From a clutch pack standpoint, changes were simple, according to the engineer, as there was enough room in the case to add a clutch and one backing plate to each of the clutch packs to handle additional power. When it came to the torque converter, things changed. “We looked at the components from a heavy-duty diesel torque converter and a high-output gas torque converter and then took the torque-carrying components from the diesel and married them to the spring and damping components from the gasoline torque converter. That’s what was needed to accommodate the approximate 22 percent across-the-board torque increase.”
So, the new torque converter can A) handle the added torque of the new engine and B) damp out the firing frequencies from the gasoline engine, which are significantly different from a diesel engine. All of the shafting and gears were able to handle the torque. Interestingly, there is no dipstick. GM has the confidence to eliminate it, and only change fluid at suggest intervals of approximately 100,000 miles, more often for those who mostly tow, or drive over mountains with full loads. Another surprise, the transmission uses GM-spec Dexron VI fluid, GMs standard since 2005, as they found no reason to change.
2019 L5P Duramax 6.6-Liter
Once we’d completed our gas powertrain interviews, we turned to the diesel side of Heavy Duty. We spoke to Max Sala, whose Italian accent tipped us to an affiliation with GM’s diesel engine center of excellence in Turin, Italy.
Max said that their objective for the new Silverado HD was to increase towing capacity and ensure functionality with the new Allison/GM transmission. Remember, the Duramax 6.6L Turbo-Diesel V-8 engine makes 445 hp. and 910 lb-ft of torque. “We added a bigger fan now 28-inches, a bigger oil cooler that is upgraded from 14 plates to 19 plates, and we fine-tuned the cylinder head gasket” Next up were improvements to the engine-brake capacity, taking into consideration towing capacity. “It’s better by 14-percent and we introduced smart activation of the engine brake,” Max continued, “There's still a button for manual activation, but for safety there's automatic activation at certain RPMs.” Under the new control system, the powertrain will recognize any need for the engine brake and activate automatically. For instance in driving down hill and forgetting to shift, the higher RPM means automatic activation. “With that, we have better after-run strategy. Every time you tow uphill, temps rise and you have a message to cool the engine when stopping. If, by chance you forget and close the door, the system cooling system activates automatically for up to 15 minutes to cool the engine for reliability.”
That isn’t the end of changes, as the engine has been completely recalibrated to match the new 10-speed Allison transmission. “Emissions have been improved and fine-tuned to maintain the best efficiency the transmission can offer to our customers.” With these changes, most importantly, Chevrolet says they are now capable of delivering full torque at any time, in any gear, and that they have done everything to the engine, transmission, driveline, drive shaft and frame to improve strength and durability. “What's important is how safe (the new HD trucks) will be and how comfortable it will be for our customers to drive these huge trailers up, and down hills.” Max concluded.
Allison transmissions have gained a peerless reputation for strength and durability. Adding a 10-speed transmission branded with the Allison name is a great choice. David Ames, now GM assistant chief engineer on the Allison transmission and liaison with Allison, is a former Allison engineer. A natural fit.
The 10-speed is a collaborative effort with joint development of the analysis, engineering, as well as testing. So, testing was performed at Allison and at GM, each with their own set of rules and test regimes. “We go back and forth”, David told us. “Today we have a ratio-span of five and this transmission has a span of 7.2, so the new 10-speed provides both more overdrive and a lower first gear.”
We asked about the projects’ starting point. “We (at GM) come out with a "here's what we're looking for" and we begin an internal development contract. It was a pretty clean sheet of paper. So, the controls on the bottom are from a smaller 10-speed, some pieces and parts, but not the entire controls package. For the most part, it's all new to handle the increased power and much larger torque.
We collaborated with Allison on this transmission (GM does have a 10-speed transmission of its own) which made it necessary to meet their (Allison) design requirements, their analysis requirements, their engineering requirements, as well as our own.
It's a very compact transmission. If you had a 6-speed for comparison, this more dense, more compact and solid to get ten speeds into a package that would still fit nicely into the vehicle and not take up too much space,” David continued.
This transmission’s torque converter has a lock-up clutch and is unique in that it will lock up in first gear, even under max loads. So, if you're pulling 33,500 pounds, you can do a first gear launch and lock up right away, which helps get rid of heat. We asked David why this is important. “Normally in first gear you're under high torque and generating a lot of heat, which puts a lot of demand on the cooling system. Locking up gets rid of that heat and the 7.2 ratio gives you a lower first gear. For instance, the six-speed uses a 3.1 first gear and the new transmission has a much lower 4.5 first gear. It's got four planetary gear sets, six clutches and the main place you'll notice the ten speeds, not only in launches and driving with heavier loads—it's very smooth—is going down a grade. Often you're trying to downshift to save brakes and having ten gears you can usually hold the right speed and not feel like you're running over the car in front of you, tapping the brakes or going too slow.”
“Also, we built in the first OEM PTO option. Note that the chain drive to the PTO is engine-speed driven rather than turbine-speed driven, which is important to many commercial customers, and it’s quieter drive than gear driven systems.”
We asked David for an overview of the combined Duramax-Allison package. “For those who need it, it’s a nice package, one we're very proud of because of the outstanding durability. I think we're going to do a better job of putting power to the road than anybody out there. Whatever torque the engine is putting out, it's getting to the road in an accurate way. I think this transmission will be far more durable than people need it to be. Four-five years from now people will understand how durable it is.”
Contributing Writer, GM-Trucks.com
Chevrolet rolled out the new 2020 Silverado HD lineup today at the Flint Manufacturing Plant where the new truck will be built. Chevy says that towing ability increased by a whopping 52% to 35,000 pounds. A heavier-duty frame compared to the current model, enables a higher gross combined vehicle weight rating (GCWR) of up to 43,500 pounds on properly equipped trucks. “We set out to make the best HD trucks on the market, bar none,” said Jaclyn McQuaid, chief engineer, Silverado HD. “We increased towing capabilities across the line, not just for dually buyers. We added class-leading towing technologies, such as 15 available camera views, to make trailering more convenient, whether pulling a large cargo trailer or fifth-wheel camper. And we made a host of changes to make tasks easier.”
The new 2020 Silverado HD will be available in five different trim levels — Work Truck, Custom, LT, LTZ and High Country — available across 22 cab, bed, chassis and driveline configurations. Chevy is offering two new powertrains. The base engine is a new 6.6L V-8 gas with direct injection producing 401 hp and 464 lb-ft of torque coupled to a six-speed automatic transmission. That’s adds up to an 11 percent increase in horsepower and a 22 percent increase in peak torque, respectively, resulting in 18 percent more towing capability. The up-powered engine is the Duramax 6.6L Turbo-Diesel V-8 engine making 445 hp and 910 lb-ft of torque mated to an all-new Allison® 10-speed automatic transmission. Chevy says that every component between the transmission and the wheels has been upgraded to enable an available 52-percent increase in max towing capability — now up to 35,500 pounds on Regular Cab, two-wheel drive, DRW, diesel models.
Chevy Lists the Following As 2020 Silverado HD highlights:
-New, more powerful 6.6L V-8 gas engine with direct injection for greater performance and stronger trailering capability with 22 percent more torque and up to 18 percent more towing compared to previous 6.0L gas engine.
-All-new Allison 10-speed automatic transmission is matched with the available Duramax 6.6L V-8 Turbo-Diesel engine for a 52 percent increase in max towing to 35,500 pounds on properly equipped models.
-Autotrac active two-speed transfer case on 4x4 models electronically controls “4 Auto” mode, allowing the truck to seamlessly shift between two-wheel drive and four-wheel drive based on road conditions.
-Advanced Trailering System technologies and new transparent trailer view: The in-vehicle trailering system features an available total of 15 available camera views (requires an installed accessory camera), such as HD Surround Vision and other unique -views including a transparent trailer feature to help provide added confidence when towing. Also features increased integration with the myChevrolet mobile app.
-HD-exclusive sculpted exterior design features the most differentiation from the Silverado 1500 ever — the roof is the only shared sheetmetal.
-Heavy-duty details designed to make work easier and more intuitive, including features such as an easy-access engine block heater outlet, easy-to-fill diesel exhaust fluid (DEF) tank with opening inside the fuel door, a more integrated snow plow prep -package and new, advanced trailering mirrors with available spot lamps and more.
-BedStep feature and larger CornerSteps makes it easier to load or reach items in the cargo box, which is designed to hold a pair of size-12 boots and up to 500 pounds.
-Larger cab enables more spacious interiors with Crew Cab models adding about 3 inches in overall length.
Chevy outlined many new driveline changes that add to the Silverado HD's towing ability. The upgraded driveline includes new, larger, more robust front and rear axles, a standard 11.5-inch ring gear on 2500HD models, and 12-inch ring gear on 3500HD diesel models. Also, 30-percent larger-diameter prop shafts provide greater strength with the high torque output of the new 6.6L gas engine and the Duramax Turbo-Diesel. Helping cool the Duramax engine is a massive 28-inch diameter fan with variable fan speed – 2.5-inches larger than the current fan.
A new 6.6L V-8 gas engine now has gasoline direct injection. Chevy uses a cast-iron Small Block for long-term durability with aluminum heads. The higher compression ratio of 10.8:1 and longer stroke produce a greater power output of 401 hp with strong performance at low rpm where it’s needed when pulling away with a loaded cargo box or trailer. Torque increases to 464 lb-ft. The 6.6L gas engine also gets dual alternators to support the electrical needs for trailering, snowplowing and other jobs.
Chevy's proven Duramax 6.6L Turbo-Diesel V-8 with 910 lb-ft of torque is th top engine option. Towing capability is increased up to 52 percent with driveline improvements. A diesel after-run feature specifically for use following a demanding towing situation is an additional new technology for the Duramax engine. The after-run allows the engine to keep running for up to 15 minutes to allow it to cool down using the fan and circulating coolant. If the driver puts the truck in park when an after-run situation is needed, an alert will appear on the driver information cluster directing them to keep the engine running for cool down. Should the customer ignore the message and exit the vehicle, the truck will restart on its own via remote start mode for cool-down. At that point the customer can walk away and the truck will turn itself off when the engine reaches an acceptable temperature.
The new Allison 10-speed automatic transmission is better at transferring all of the Duramax’s torque to the pavement, allowing more torque to be put to the ground in lower gears, enhancing the overall driving dynamics and trailering with smoother gear changes and shorter steps between them. It also supports smart engine braking, which can help reduce brake wear. The Duramax/Allison combination’s standard axle ratio is lowered to 3.42:1, which reduces engine speed, therefore enhancing refinement. “The 6.6L Duramax diesel and Allison® transmission is a legendary combination in the HD truck market with proven durability and capability that our customers expect,” said McQuaid. “For 2020, we made the combination even better and upgraded nearly every driveline component.”
An all-new, factory-integrated engine-driven Power Take Off (PTO) is available that eliminates the need for an aftermarket unit. Exclusively offered with the Allison® 10-speed transmission on select diesel models, it’s the first fully integrated PTO system of its kind in the HD truck segment, with the PTO’s drive gear operated via chain to direct engine power. And because it is engine-driven rather than turbine-driven, owners can use the PTO while the vehicle is idling. A button inside the cab enables the PTO, and a mode selector allows adjustment of load and torque output.
HD Highlights Include:
- Smother door skins to make attaching signage easier for owners
-Relocated engine-block heater. Designers moved the engine-block heater outlet to a more convenient, external location on the driver’s side of the truck, integrated into the front bumper, eliminating the need for cords hanging out of the grille or to open the hood for plug-in. The block heater is standard with diesel models and available with the new 6.6L gas engine.
-More-intuitive snow plow package8. The front end of the truck is designed for easy removal of the air dam and skid plate for easier and more intuitive mounting of the plow hardware. The design even eliminates the need to drill additional holes in the front bumper. And when the plow blade is removed, the Silverado HD returns to form by maintaining a smooth, integrated appearance without visible hardware.
-Diesel DEF tank/filler enhancements. The Diesel Exhaust Fluid tank is relocated farther back on the Silverado HD’s frame and out of sight from the exterior, and the inlet is located next to the fuel filler for more convenient filling. An electronic gauge readout for the DEF fluid level is added to the Driver Infotainment Center of diesel-equipped models.
-Redesigned trailering mirrors with improved perimeter lighting. New, larger and more functional door-mounted trailering mirrors are standard on all 2500HD and 3500HD models. The mirrors extend and retract using a four-bar-link system that makes for smoother operation, whether done with power or manually. The surface area of the mirrors is larger, for a greater field of view compared to the current model, and an available power extension feature makes it easier to adjust the view from the driving position.
-New for 2020 is the forward-facing spot lamp on each mirror that shines light at about a 45-degree angle, providing illumination on the job site or camp site. There also are side-view cameras mounted within the mirror housings, and when equipped, mirror-mounted puddle lamps and two rearward-facing spot lamps are also available.
- Aero Shutters on 2500 and 3500 SRW models improve efficiency.
- Diesel models get a more prominant hood scoop
- Beds are no longer shared with standard duty Silverados, but are custom to the HD
Work Truck: Distinguished with a unique, black “CHEVROLET” flow-through grille bar. Seventeen-inch wheels are standard on 2500HD and 3500HD with dual rear wheels (DRW); 18-inch wheels are standard on 3500HD with single rear wheels (SRW).
Custom: New to the Silverado HD lineup and exclusive on 2500HD, the Custom trim offers standard 20-inch wheels and body-color trim details for a more contemporary design expression.
LT: Featuring chrome-trimmed vertical grille elements and a bright grille bar with the flow-through “CHEVROLET” name. 2500HD models feature 17-inch aluminum wheels, 3500HD SRW models feature 18-inch aluminum wheels and 3500HD DRW models feature 17-inch steel wheels.
LTZ: Takes bright trim to the next level, including a bright grille surround with the flow-through “CHEVROLET” bar and chrome-accented grille inserts. It also features LED reflector headlamps, LED daytime running lamps and LED taillamps. 2500HD and 3500HD SRW models feature standard 18-inch aluminum wheels with 20-inch wheels available. 3500HD DRW has standard 17-inch steel wheels and 17-inch polished forged-aluminum wheels are available.
High Country: The most dramatic and expressive trim in the lineup, with a distinctive fascia featuring a grille with the Chevy bowtie and two-tone metallic grille trim, and LED lighting. 2500HD and 3500HD SRW models feature 20-inch polished aluminum wheels and the 3500HD DRW features 17-inch polished forged-aluminum wheels.
Chevy Also Created This Matrix Showing the Comparison To Other Trucks
Please see our separate story for full specifications.
Contributing Writer, GM-Trucks.com
Here are the 2020 Silverado HD specifications provided today:
*All towing capabilities measured using SAE J2807 metrics.
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