Heavy-Duty Power from Chevy’s HD Trucks
With 401 horsepower and 464 lb.-ft. of torque on tap, the L8T crate engine is the largest-displacement LT-family engine in our lineup, offering plenty of low-rpm torque. Direct injection offers more precise fuel control than port injection, enabling a comparatively high compression ratio of 10.8:1 in the engine, which contributes to its high output.
It’s built with a forged steel crankshaft and other high-strength parts. Additional features such as oil-spray cooling for the pistons and a cast iron, long-skirt cylinder block with six-bolt, cross-bolted main caps contribute to the engine’s strength and durability. Comes with production style exhaust manifolds.
Our L8T Long Block includes the direct injection cylinder heads and coil-on-plug ignition system, as well as the oil pan with dipstick, but does not include the intake manifold, throttle body, engine-mounted high-pressure direct injection fuel pump or fuel injectors. All must be sourced separately to complete the engine assembly. Additionally, the Front End Accessory Drive system is not included. See Installation Notes for recommendations.
Part Number: 19433748
Engine Type: Gen V Small Block V-8 direct injection spark ignition
Displacement (cu in): 400 (6.6L)
Bore x Stroke (in / mm): 4.060 x 3.860 (103.25 mm x 98 mm)
Block (P/N 19420904): Cast iron with 6-bolt nodular main bearing caps
Crankshaft (P/N 12708884): Forged steel
Connecting Rods (P/N 12675746): Forged powder-metal
Pistons (P/N 12699527-R, 12699529-L): Hypereutectic aluminum
Camshaft Type (P/N 12672469): Billet steel hydraulic roller
Valve Lift (in): 0.500 intake / 0.492 exhaust
Camshaft Duration (@ 0.050 in): 193º intake / 199º exhaust
Cylinder Heads (P/N 12703610): Aluminum rectangular port D/I with 59.02cc chambers
Valve Size (in): 2.130 hollow intake / 1.590 inconel exhaust
Compression Ratio: 10.8:1 (nominal)
Rocker Arms (P/N 12619829): Investment cast roller trunnion
Rocker Arm Ratio: 1.8:1
Intake manifold (P/N 12639087): Composite
Fuel delivery: High-pressure direct injection (2,175 psi / 150 bar)
Recommended Fuel: 87 octane
Ignition system: Coil-on-plug
Maximum Recommended RPM: 5600 rpm
Reluctor wheel: 58X
• Engine is shipped with high-pressure direct-injection fuel pump installed
• Front End Accessory Drive system must be ordered separately and includes hydraulic power steering, with center pulley. Pulley-mounted fan not recommended
• Use Front End Accessory Drive system P/N 19433745 for applications with air conditioning and Front End Accessory Drive system P/N 19433746 for applications without air conditioning
• Includes 8-bolt flexplate for automatic transmissions
• Used with Engine Control kit 19433736 (must use 6L80 transmission). Includes programmed controller, wire harness, pedal, oxygen sensors and mounts, MAF, Fuel Line Pressure Sensor, and Fuel Pump Power Module (FPPM).
• Available in Connect & Cruise (with 6L80 transmission)