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GM 6.6L L8T V-8

General Motors 6.6L L8T Gas Engine Specs

The 6.6L L8T gasoline engine replaces the 6.0L V-8 in Chevrolet and GMC 2500HD/3500HD applications. At 401 horsepower and 464 lb-ft of torque, the 6.6L offers significantly greater performance than the 360 horsepower, 380 lb-ft 6.0L V-8. The L8T is a standard cam-in-block pushrod V-8 that runs on regular 87 octane unleaded gasoline despite its relatively high compression ratio. It features a deep skirted cast iron engine block, which provides additional rigidity to the bottom end of the engine and reduced engine harmonics. The engine is not to be confused with the 6.6L Duramax diesel, although their bore diameter, stroke length, and therefore overall displacement are similar.

GM 6.6L L8T Specs

Engine 6.6L L8T V-8
Manufacturer General Motors
Applications/Production Years 2020+ Chevrolet Silverado 2500 HD/3500 HD
2020+ Chevrolet Silverado 3500 HD chassis cab
2020+ GMC Sierra 2500 HD/3500 HD
2020+ GMC Sierra 3500 HD chassis cab
Production/Assembly Plant(s) Tonawanda Engine Plant, Buffalo, New York
Displacement 400.55 CID (400 CID nominal), 6.56 liters (6.6 liters nominal)
Configuration V-8
Bore 4.065 in (103.25 mm)
Stroke 3.858 in (98.0 mm)
Bore/Stroke Ratio 1.05 (slightly oversquare)
Compression Ratio 10.8 : 1
Firing Order 1 - 8 - 7 - 2 - 6 - 5 - 4 - 3
Engine Block Material Cast iron
Cylinder Head Material Aluminum alloy
Intake Manifold Material Composite
Exhaust Manifold Material Cast stainless steel
Injection System Direct injection
Aspiration Naturally aspirated
Reciprocating Assembly Forged steel crankshaft, bullet steel camshaft, forged powder metal connecting rods, 6 bolt cross-bolted cast nodular main bearing caps
Valvetrain 2 valves per cylinder (16 valve), Overhead valve (OHV), standard cam-in-block pushrod V-8, variable valve timing, hydraulic roller lifters, Inconel alloy exhaust valves
Engine Oil Capacity 8.0 quarts w/ filter
Engine Oil Spec Ambient temp > -20° F SAE 5W-30 motor oil
Ambient temp < -20° F SAE 0W-30 motor oil
Fuel 87 octane unleaded gasoline
Horsepower 401 hp @ 5,200 rpm
Torque 464 lb-ft @ 4,000 rpm
Max Engine Speed 5,600 rpm
Engine Dimensions Length 29.75 inches
Width 26.10 inches
Height 31.30 inches

6.6L L8T V-8 Horsepower & Torque Graph

6.6L L8T gas engine horsepower and torque chart
6.6L L8T Horsepower & Torque
2020 Chevrolet Silverado 2500HD/3500HD, GMC Sierra 2500HD/3500HD
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