Chevrolet L5P Specifications
| Engine Model: Chevrolet L5P |
| Engine Type: 4-cycle 8-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 403 cu.in (6.6 L) |
| Rated Engine Power: 445-470 Hp (332-350 kW) at 2800 rpm |
| Fuel System Type: Common rail fuel injection |
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The Chevrolet L5P represents the fifth-generation
iteration of the 6.6L Duramax V8 turbo-diesel engine, debuting in 2017 for the
2017.5 model year as the successor to the LML. This engine was engineered to
rectify longstanding reliability concerns, specifically targeting the
high-pressure fuel system vulnerabilities that plagued its predecessor.
The L5P is distinguished by a comprehensive architectural overhaul,
transitioning to a Denso high-pressure common-rail system from the problematic
Bosch CP4 pump, and incorporating a factory-installed in-tank lift pump - a
first for the Duramax lineage.
This powertrain is widely recognized for its enhanced durability, improved
thermal management, and substantial increase in both horsepower and torque
output, solidifying its status as a benchmark in the heavy-duty pickup segment.
Its robust construction includes a cast-iron block, forged steel crankshaft, and
advanced variable geometry turbocharger, delivering exceptional towing
capability and reliability under extreme operational stresses.
Engine Configuration: 90-degree V8, turbo-diesel, four-stroke cycle.
Displacement: 6.6 L (403 cu.in)
Bore x Stroke: 103 mm x 99 mm (4.055 in x 3.897 in).
Compression Ratio: 16.0:1.
Firing Order: 1-8-7-2-6-5-4-3.
Power Output:
2017-2023 Models: 445 hp (332 kW) at 2,800 rpm.
2024-Present Models: 470 hp (350 kW) at 2,800 rpm.
Torque Output:
2017-2023 Models: 910 lb-ft (1,234 Nm) at 1,600 rpm.
2024-Present Models: 975 lb-ft (1,322 Nm) at 1,600 rpm.
Engine Management: Bosch EDC17 engine control unit (ECU) with a 32-bit
processing system.
Governed Speed: 3,500 rpm maximum (electronically limited).
The cylinder block is constructed from high-strength
gray cast iron with a deep-skirt design to maximize structural rigidity and
minimize noise, vibration, and harshness. It features induction-hardened
cylinder walls, eliminating the need for separate cylinder liners. The block is
a closed-deck design, providing superior head gasket sealing capability under
high cylinder pressures generated by the turbocharging system.
Bulkhead structures have been reinforced compared to the previous LML generation
to accommodate increased torque loads. The block incorporates cross-bolted main
bearing caps using six bolts per cap (four vertical, two horizontal) to secure
the crankshaft, enhancing bottom-end strength and durability.
The cylinder heads are manufactured from cast aluminum
alloy and utilize a four-valve-per-cylinder configuration. Each cylinder head
features dual overhead valves actuated by a pushrod valvetrain. The intake
valves are 36 mm in diameter, while the exhaust valves measure 32 mm, with the
exhaust valves filled with sodium to facilitate efficient heat transfer away
from the valve face.
The valvetrain employs hydraulic roller lifters and a single cast-iron camshaft
located within the engine block. The cylinder heads incorporate a unique water
jacket design that optimizes coolant flow around the injector nozzles and
exhaust ports to manage thermal loads. The combustion chamber design is a
re-entrant style integrated directly into the piston crown, optimizing swirl and
air-fuel mixture for complete combustion.
The L5P marked a significant departure from previous
Duramax engines by utilizing a Denso HP4 high-pressure common-rail fuel system,
replacing the Bosch CP4 system. This system operates at a maximum injection
pressure of 2,000 bar (29,000 psi). A critical feature is the inclusion of a
factory in-tank electric lift pump, which supplies fuel to the high-pressure
pump at a regulated pressure, significantly reducing the strain on the injection
pump and improving system reliability.
The high-pressure pump is a two-piston, two-cylinder design mounted to the front
of the engine, driven by the gear train. Piezoelectric injectors provide precise
injection control, enabling up to seven injection events per combustion cycle
for optimized power delivery, reduced combustion noise, and improved emissions
management. The fuel filtration system incorporates a 10-micron primary fuel
filter with a water-in-fuel sensor and a secondary filter mounted on the engine.
The lubrication system utilizes a high-volume,
gear-type oil pump mounted to the front of the crankshaft. This pump is designed
to deliver consistent oil pressure across the entire engine speed range. The oil
pan is a two-piece design consisting of a structural upper pan and a stamped
steel lower pan. The system incorporates an oil cooler, which is an integrated
unit mounted within the engine valley, utilizing engine coolant to regulate oil
temperature.
A full-flow oil filter with a bypass valve is mounted on the engine block. The
total oil capacity, including the filter, is 10 quarts (9.5 L). The engine
utilizes a specific low-ash diesel engine oil meeting GM specification dexosD to
ensure proper functioning of the diesel particulate filter (DPF).
The cooling system is a high-capacity, pressurized
system designed to manage the substantial thermal load of the engine under
maximum towing conditions. It features a variable-speed, electronically
controlled engine-driven fan that engages based on coolant temperature, air
conditioning pressure, and transmission oil temperature. The radiator is a
high-density, dual-row aluminum core design with a 34-inch width to maximize
frontal area.
A separate coolant circuit is dedicated to the charge air cooler, which is an
air-to-air unit mounted in front of the radiator. The engine employs a
centrifugal-type water pump with a cast housing, and a 95°C (203°F) thermostat
regulates operating temperature. A coolant surge tank with a 15 psi pressure cap
maintains system integrity and allows for thermal expansion.
| Intake and Exhaust Systems |
Air Induction System: The engine utilizes a functional
hood scoop in Chevrolet Silverado HD and GMC Sierra HD applications, which
provides approximately 60% of the cold air intake volume directly to the air
cleaner assembly. The air filter housing incorporates a high-efficiency paper
element with a 10,000-mile service interval under normal conditions.
Exhaust System: The exhaust system integrates a close-coupled diesel oxidation
catalyst (DOC), a diesel particulate filter (DPF), and a selective catalytic
reduction (SCR) system with diesel exhaust fluid (DEF) injection. A passive
exhaust brake function is integrated into the turbocharger control strategy.
Turbocharger: A BorgWarner variable geometry
turbocharger (VGT) is employed, featuring electronically controlled vanes that
adjust the aspect ratio of the turbine housing to optimize boost pressure and
exhaust braking performance. Maximum boost pressure is 28 psi (1.93 bar).
Emissions Control: The engine utilizes cooled exhaust gas recirculation (EGR)
with a high-pressure loop, drawing exhaust gases from the exhaust manifolds
before the turbocharger. An EGR cooler is integrated into the cooling system to
reduce intake air temperatures.
Overall Length: 850 mm (33.5 in) from front accessory
drive to flywheel housing.
Overall Width: 890 mm (35 in) at the widest point of the exhaust manifolds.
Overall Height: 790 mm (31.1 in) from the lowest point of the oil pan to the
highest point of the intake manifold.
Dry Weight: 363 kg (800 lb) without fluids, including flywheel and turbocharger.
Engine Oil:
Specification: SAE 5W-40 or 15W-40 meeting GM dexosD.
Capacity with Filter: 10 quarts (9.5 L).
Change Interval: 12,000 km (7,500 mi) under normal conditions.
Change Interval: 6,000 km (3,700 mi) under severe service.
Cooling System:
Capacity: 26 quarts (24.6 L) for total system (engine and radiator).
Coolant: GM DEX-COOL extended life antifreeze, 50/50 mixture with distilled
water.
Change Interval: 240,000 km (150,000 mi) or 5 years.
Fuel System:
Primary Fuel Filter: Change interval of 24,000 km (15,000 mi).
Fuel Requirement: Ultra-low sulfur diesel (ULSD) with a minimum cetane rating of
45.
Air Filter Service Interval: Inspect every 24,000 km (15,000 mi); replace as
indicated by filter restriction gauge. Valve Lash Adjustment: The L5P utilizes
hydraulic lifters, requiring no routine valve lash adjustment.
Cylinder Head Bolts (per
head):
M12 Bolts (long): 90 Nm (66 lb-ft) + 100 deg rotation.
M10 Bolts (short): 60 Nm (44 lb-ft) + 90 deg rotation.
M8 Bolts (outer): 25 Nm (18 lb-ft) + 60 deg rotation.
Main Bearing Cap Bolts:
Vertical Bolts (M14): 90 Nm (66 lb-ft) + 90 deg rotation.
Cross Bolts (M12): 90 Nm (66 lb-ft) + 60 deg rotation.
Connecting Rod Cap Bolts (M10): 35 Nm (26 lb-ft) + 100 deg rotation.
Crankshaft Damper Bolt (M16): 90 Nm (66 lb-ft) + 90 deg rotation.
Flywheel/Flexplate Bolts (M12): 100 Nm (74 lb-ft) + 60 deg rotation.
Intake Manifold Bolts: 15 Nm (11 lb-ft).
Exhaust Manifold Bolts: 30 Nm (22 lb-ft).
Valve Cover Bolts: 12 Nm (106 lb-in) in a crisscross pattern.
High-Pressure Fuel Pump Mounting Bolts: 25 Nm (18 lb-ft) + 45 deg rotation.
Fuel Injector Clamp Bolts: 9 Nm (80 lb-in) + 105 deg rotation.
Turbocharger Mounting Nuts: 45 Nm (33 lb-ft) for main mounting.
Turbocharger Mounting Nuts: 25 Nm (18 lb-ft) for VGT actuator.
The Chevrolet L5P engine
serves as the exclusive diesel powertrain for General Motors’ heavy-duty truck
platform across multiple generations:
Chevrolet Silverado 2500HD (2017-Present): Available in Work Truck, Custom, LT,
and High Country trims, paired with rear-wheel drive or four-wheel drive.
Chevrolet Silverado 3500HD (2017-Present): Offered in single-rear-wheel and
dual-rear-wheel configurations, including Chassis Cab variants for commercial
applications.
GMC Sierra 2500HD (2017-Present): Available in base, SLE, SLT, AT4, and Denali
trims.
GMC Sierra 3500HD (2017-Present): Provided in single-rear-wheel,
dual-rear-wheel, and Chassis Cab configurations.
Transmission Pairing:
2017-2019 Model Years: Allison 1000 6-speed automatic transmission (6L90) with a
cast-iron housing and internal transmission oil cooler.
2020-Present Model Years: Allison-branded 10-speed automatic transmission
(10L1000), developed jointly with GM, featuring a wider gear spread for improved
towing capability, fuel efficiency, and reduced driveline stress.
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