2020 Silverado HD and Sierra HD Powertrains

The all-new 2020 Silverado HD (Fig. 9) and Sierra HD trucks offer two powertrain choices: the all-new 6.6L V8 gasoline engine (RPO L8T) paired with the 6-speed 6L90 automatic transmission (RPO MYD) and the Duramax 6.6L V8 diesel engine (RPO L5P) mated to the all-new Allison 10L1000 10-speed automatic transmission (RPO MGM, MGU).


Fig. 9


6.6L V8 Gasoline Engine

The new 6.6L V8 gas engine (Fig. 10) uses a cast-iron small block with aluminum heads, a forged steel crankshaft, forged powder-metal connecting rods and additional high-strength components for long-term durability. It generates 401 horsepower and 464 lb.-ft. of torque — that’s 22 percent more torque and up to 18 percent more towing capability when compared to the previous 6.0L V8 gas engine. With variable valve timing and spark ignited direct injection (SIDI), it delivers precise fuel control that enables a compression ratio of 10.75:1 for enhanced performance and fuel efficiency.


Fig. 10


The fuel system is an electronic returnless on-demand design that reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank for lower evaporative emissions. The electric turbine-style fuel pump attaches to the fuel tank fuel pump module inside the fuel tank. The high pressure fuel pump, fuel rail pressure, fuel injection timing, and injection duration are controlled by the Engine Control Module (ECM). The fuel pressure sensor is a serviceable 5 V, 3-pin device that is located on the fuel feed line forward of the fuel tank.

The engine oil capacity with filter is 8 quarts (7.6 liters) and dexos® 1 Approved – GEN 2 viscosity grade 5W-30 engine oil is required.

The 6.6L gas engine also will be offered with dual alternators to support the electrical needs for trailering, snowplowing and other jobs.


Duramax 6.6L V8 Diesel Engine

Maximum power and towing capability in new HD trucks comes from the proven Duramax 6.6L V8 turbo-diesel engine (Fig. 11) that produces 445 horsepower and 910 lb.-ft. of torque. Its towing capability is increased up to 52 percent with driveline improvements including the addition of the all-new Allison 10L1000 10-speed automatic transmission.


Fig. 11


The hardened engine block uses a deep skirt design for increased rigidity while the light-weight aluminum cylinder heads quickly dissipate heat. The four valves per cylinder and ports have a high swirl design to improve combustion.

The engine uses eight ceramic glow plugs that enable greater efficiency through higher temperature capability and faster preheating time. Ceramic glow plugs are considered one-time-use because they are much more sensitive to damage than conventional glow plugs. Anytime a ceramic glow plug is removed from the cylinder head, install a new glow plug. Clean the glow plug bore of any carbon build-up before installing the new plug.

The engine oil capacity with filter is 10 quarts (9.5 liters) and 15W-40 viscosity grade engine oil with an API CJ-4 or CK-4 designation is required. In extreme cold weather below 0°F (–18°C), use 5W-40 engine oil.

The diesel exhaust aftertreatment system is designed to reduce the levels of hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), and particulate matter (PM) in the engine exhaust gases. Reducing these pollutants to acceptable levels is achieved using a Diesel Oxidation Catalyst (DOC), Select Catalyst Reduction (SCR), and a Diesel Particulate Filter (DPF). Proper operation of the diesel exhaust aftertreatment system requires the use of ultra-low sulfur diesel (ULSD) fuel and Diesel Exhaust Fluid (DEF).

The DEF tank is relocated farther back on the HD truck’s frame and out of sight from the exterior. The DEF filler inlet is located next to the fuel filler for convenient filling. (Fig. 12) An electronic gauge display on the Driver Information Center (DIC) indicates the DEF fluid level. In addition, as the DEF level becomes low, warning are displayed on the DIC. As the tank nears empty, vehicle speed will be limited in a series of steps. At least 2 gallons (7.57 L) of DEF must be added to release the speed limitation.


Fig. 12


After-Run Cooling

The new diesel after-run feature on the Duramax engine was specifically engineering for use following a demanding towing situation. The after-run system allows the engine to keep running for up to 15 minutes to allow it to cool down by running the larger 28-inch (71 cm) diameter, variable speed fan and circulating coolant. The system notifies the driver that required engine cooling is needed when the transmission is shifted to Park by displaying an alert on the Driver Information Center (DIC) that states to keep the engine running for cool down. If the message is ignored and the vehicle is turned off and exited, the truck will restart on its own via remote start mode for cool-down. The truck will turn off when the engine reaches an acceptable temperature.


Engine Coolant Heater

The engine coolant heater outlet has been moved to a more convenient, external location on the driver’s side of the truck, integrated into the front bumper (Fig. 13), which eliminates the need for a cord to hang out of the grille or to open the hood for plug-in. The coolant heater operates using 110 V alternating current from an external power source and is designed to warm the coolant in the engine block area for improved starting in weather conditions that are colder than 0°F (−18°C).


Fig. 13


Vehicles with an engine block heater should be plugged in at least four hours before starting. An internal thermostat in the plug-end of the cord may exist, which will prevent engine coolant heater operation at temperatures warmer than 0°F (−18°C). The coolant heater also helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

For additional information on the new 2020 Silverado HD and Sierra HD, refer to Bulletin #19-NA-091.


– Thanks to Kevin Minor and Sherman Dixon



Work It: All-New 2020 Chevrolet Silverado HD and GMC Sierra HD Debut
All-New Allison 10-Speed Automatic Transmission

Comments are closed.