This is a full-sized pickup which means like most that came before it, getting deep under the hood means climbing up onto it and diving in. And once you’re there a lot of what you came to see is hidden beneath but we managed to get some good views.
The 5.3 liter L83 EcoTec3 V8 was new starting in 2014 and represents GM’s strategy to save fuel and offer horsepower with three key technologies. These are direct injection, cylinder deactivation and continuously variable valve timing.
Together they represent a significant technological upgrade to the small-block V8 that has its design and DNA roots back into the 1950’s. These new features allow it to have a high 11.0:1 compression ratio and still run on regular gas.
Here it produces 355 horsepower and 383 pound-feet of torque and comes mated exclusively to an 8-speed Hydra-Matic 8L90 automatic transmission.
The L83 engine has aluminum heads and an aluminum deep skirt block with iron cylinder liners. Structural details like cross-bolted main bearing caps and a structural oil pan keep it tough for truck duty. With an 8-quart oil capacity, it has sensors that monitor oil quality and enable the computer to recommend oil change time.
A new domed valve cover design has an integrated PCV system, eliminating the long term maintenance of valves and hoses of the past. Saw cut iron exhaust manifolds also promise for better long term gasket sealing with less surface movement due to temperature differences.
Intake air moves from the filter box through a huge sound deadening chamber before it flows into the throttle body and ultimately the composite plastic intake manifold. Fuel system hardware isn’t much seen with the direct fuel injection, unlike the previous generation port injection.
An oil-pressure controlled cylinder-deactivation system shuts down the lifters for four of its cylinders, cuts off fuel, and spark effectively making it a V4 engine during coast or times of low power need. When power is needed or asked for, it fires them back up in less than 20 milliseconds.
In day to day driving it’s barely noticeable when the change is taking place, the only indicator you really get is the readout on the instrument cluster letting you know what’s going on. It’s smoother in its transitions I think than the same type of system in RAM pickups.
Extra power and fuel savings also comes with variable valve timing which is handled at the cam, enabling advanced timing when power is needed and retards timing for better fuel efficiency when it isn’t.
Looking around under the hood one unique thing I noticed is its offset water pump and thermostat that hangs off to the side almost like an accessory. GM says this offers better thermal efficiency, but I also see it as appearing to be easier to replace here too.
Other obvious notes are the battery which is located back up against the passenger firewall. Getting it out might require the removal of that brace you see there. And note that it has an insulating wrap on it so you don’t short circuit jumper cables against it. Electronics like the ECU are located up front on the driver side ahead of the brake master cylinder and power booster assembly.
