The heart of the Silverado 2500HD and 3500 HD models
In addition to the complete L8T crate engine, Chevrolet Performance offers the L8T Long Block — the high-output, direct-injected foundation of the Gen V Small Block-based 6.6L engine offered in the Silverado 2500HD and 3500HD models.
PART NO. 19433748
401 HP @ 5,200 RPM
464 LB-FT @ 4,000 RPM
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 ration of 10:8:1 in the engine, which contributes to its high output.
Connect & Cruise Powertrain System
Connect & Cruise Crate Powertrain Systems provide factory-matched engine-and-transmission combinations that include specially calibrated controllers and wire harnesses designed for retrofit installations in older vehicles.
†Parts and labor warranty when installed by a GM Dealer or qualified installing independent Service Center (ISC) or when sold over the counter and REPAIRED by a GM Dealer or qualifying ISC. Parts only when consumer repaired or installed in non-highway application. Coverage limited to defects in material and/or workmanship of the specific part only. Warranty valid when all required components are installed on the same vehicle and purchased on one invoice.
††Must be purchased from a participating U.S. dealer or Chevrolet Performance Authorized Reseller. Mail-in rebate offer not available with other offers. See gmpartsrebates.com for details, applicable rebate amounts, and rebate form. Rebates must be submitted by 1/31/24. Rebates may be submitted over two invoices within 120 days of each other. Allow 6 to 8 weeks for delivery of debit card. Offer valid 1/1/23 to 12/31/23. Unless specifically noted to the contrary herein, vehicles equipped with Chevrolet Performance parts that are emissions-related may not meet U.S., Canadian, and state and provincial laws and regulations relating to motor-vehicle emissions. These parts are designed and intended for use in vehicles operated exclusively for competition: in racing or organized competition on courses separate from public streets or highways. Visit www.chevroletperformance.com/emissions for more details. Rebate form and details available at chevrolet.com/performance/offers.
Installation Guides
Find everything from vital data about your engine’s capabilities to how to install it into your build.
L8T Tech Specs
- 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): 193° intake / 199° 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
- Throttle body (P/N 12730580): 87mm diameter (single-bore)
- 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
- Balanced: Internal
Mobil 1 is now The Official Motor Oil of Chevrolet Performance.
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