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Product Details
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Key Features
Heavy Duty Torque from Chevrolet’s HD Truck Programme
The L8T is the heavy duty variant of Chevrolet’s Gen V 6.6L family, engineered for commercial grade reliability and consistent low rpm torque delivery. Rated at 401 horsepower and 464 lb ft, the L8T provides exceptional drivability for towing oriented builds, utility vehicles, converted 4x4 platforms and high mass custom projects that prioritise durability.
The engine uses a cast iron block with reinforced main caps, forged steel crankshaft and a long skirt designed to increase rigidity under sustained load. The high pressure direct injection system and hydraulic roller camshaft enhance combustion control while maintaining strong mid range torque. The rotating assembly and oiling system are designed for long service life in high stress operating environments.
Specifications
Engine Type: Gen V Small Block V8
Displacement: 400 cu in (6.6L)
Bore x Stroke: 4.065 x 3.860 in (103.25 x 98 mm)
Power: 401 hp at 5,200 rpm
Torque: 464 lb ft at 4,000 rpm
Compression Ratio: 10.8:1
Maximum RPM: 5,600
Engine Construction
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Cast iron block with six bolt nodular iron main bearing caps
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Forged steel crankshaft
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Forged powdered metal connecting rods
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Hypereutectic aluminium pistons with oil spray cooling
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Aluminium rectangular port cylinder heads with 59.02 cc chambers
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L8T composite intake manifold
Camshaft and Valvetrain
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Hydraulic roller camshaft
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Valve lift: 0.500 in intake / 0.492 in exhaust
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Duration at 0.050 in: 193 deg intake / 199 deg exhaust
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Investment cast roller trunnion rocker arms
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1.81:1 rocker ratio
Advanced Features
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High pressure direct injection
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Coil on plug ignition
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Continuously variable valve timing
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Premium pump fuel
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58x reluctor wheel
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Internal balancing
Installation Requirements
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Requires high pressure direct injection fuel pump installed
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Front End Accessory Drive System must be ordered separately and includes hydraulic power steering. Pulley mounted fans are not recommended
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2024 and later versions use Engine Control Kit 19432576 for 6L80 E transmissions. Use 19432566 for 10L90 E
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Includes eight bolt flexplate
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Assembly does not include throttle body tube, dipstick or fill tube
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Electronics, harness and oxygen sensors not supplied
Notes
The L8T is engineered for sustained heavy load operation and is the recommended LT option for commercial duty conversions. Intended for pre 1976 street vehicles or off road builds. Premium unleaded fuel recommended.
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Product Specifications
Block
Cast iron with 6-bolt nodular bearing caps
Bore x Stroke
4.062 in. x 3.860 in. (103.25 mm x 98 mm)
Camshaft Duration (@ 0.050 in)
193° intake / 199° exhaust
Camshaft Type
Billet steel hydraulic roller
Compression Ratio
10.8:1
Connecting Rods
Forged powder-metal
Crankshaft
Forged steel
Cylinder Heads
Aluminum rectangular port D/I with 59.02cc chambers
Displacement
400 cu. in. (6.6L)
Engine Type
Gen-V Small-Block V8
Engine Type
LT
Fuel delivery
Fuel delivery
Ignition system
Coil-on-plug
Intake manifold
Composite
Pistons
Hypereutectic aluminum
Reluctor Wheel
58x
Rocker Arm Ratio
1.8:1
Rocker Arms
Investment-cast
Throttle body
87mm diameter (single-bore)
Valve Lift (in)
.500 intake / .492 exhaust
Valve Size (in.)
2.130 intake / 1.590 exhaust