6.6L V8 L8T Engine from GM Powertrain

6.6L V-8 L8T

LOW-SPEED TORQUE PRODUCER

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HORSEPOWER: 401 HP (299 KW) @5200 RPM*
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TORQUE: 464 LB-FT (629 NM) @4000 RPM*
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FUEL TYPE: REGULAR GASOLINE (87 OCTANE)
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6.6L V-8 L8T Features

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The L8T is meant for grunt work, thanks to an impressive 464 lb-ft. of peak torque that arrives 200 rpm sooner (and is 22 percent more) than GM’s previous 6.0L V-8 HD gasoline engines. Direct injection technology provides precise fuel control and enables a higher compression ratio that broadens the torque curve and contributes to a power output of 401 hp. This broad torque band provides a stronger feeling of on-demand power at all speeds.

Watch: 6.6L V-8 L8T Engine

Discover the engineering and capabilities of the 6.6L V-8 L8T engine from GM Powered Solutions. Durably designed to handle tough jobs, this rugged engine will stand up to heavy-duty applications with efficiency and high performance.
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New 6.6L V8 Controller

GM Powered Solutions’ new 6.6L heavy-duty engine control module (ECM) delivers a GM-approved foundation and customizable control architecture that prevents reverse-engineering, accelerates development, and delivers more reliable commercial-grade performance.
  • A GM-provided base engine calibration.
  • The new 6.6L heavy-duty gas engine control module provides integrators with a GM-approved foundation with the base engine calibration pre-loaded. Designed as a ready-to-run package for engine dynamometer testing, it minimizes the need for reverse engineering and optimizes the time and cost associated with baseline calibration work.
  • This ECM features a flexible, customizable control platform that allows integrators to tune the engine to their on-road applications, from last-mile delivery routes to heavy-load construction environments.  
  • Reverse engineering could introduce instability, electrical issues, and premature component failure. With GM-provided baseline engine calibration, integrators can build more durable and reliable powertrains that perform consistently over the long term. 
  • Pairing the 6.6L heavy-duty gas engine with this new ECM creates a robust solution engineered for the demands of on-road commercial vehicles and high-utilization fleets that need dependable, repeatable performance.

6.6L V-8 L8T Specifications
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Type:

6.6L V-8

Displacement:

6564 cc (400 CI)

Engine Orientation:

Longitudinal

Compression Ratio:

10.8:1

Valve Configuration:

Overhead Valves

Valves per Cylinder:

Two

Assembly Sites:

Tonawanda, NY

Valve Lifters:

Hydraulic Roller

Firing Order:

1–8–7–2–6–5–4–3

Bore x Stroke:

103.25 x 98.0 mm

Fuel Type:

Regular Gasoline (87 Octane)

Horsepower:

401 hp (299 kW) @5200 RPM*

Torque:

464 lb-ft (629 Nm) @4000 RPM*

Maximum Engine Speed:

5600 RPM

Emissions Control:

Catalytic Converter, Three-Way Catalyst, Positive Crankcase Ventilation

Block:

Cast Iron

Cylinder Head:

Cast Aluminum

Intake Manifold:

Composite

Exhaust Manifold:

Stainless Steel

Main Bearing Caps:

Cast Nodular

Crankshaft:

Forged Steel

Camshaft:

Billet Steel

Connecting Rod:

Forged Powder Metal

*As tested in Chevrolet Silverado Heavy-Duty