Chevy 4.2L LL8 L6 Remanufactured Engine – 2008-2009

Description

Neutralize high-RPM torsional crankshaft vibration and eliminate cam timing drift under 277 lb-ft sustained cargo hauling across demanding interstate freight transit runs using the Chevy 4.2L LL8 Remanufactured Engine. Built for 2008 to 2009 commercial fleet applications, this final iteration of the Atlas inline-six features sophisticated electronic engine management and 291 continuous horsepower.

Featuring advanced A356-T6 cast aluminum deep-skirt architecture, this engine utilizes centrifugal cast iron sleeves diamond-honed to a 45-degree plateau crosshatch. Block decks are milled to an Ra 25 micro-inch finish. A micro-polished forged steel crankshaft spins within seven cross-bolted main caps, transferring power through powdered metal connecting rods. Dry block weight equals 425 lbs with a seven-quart structural oil pan capacity.

Key Features of Chevy 4.2L

Fleet operators buy Chevy 4.2L long block engine units to minimize maintenance costs on regional transport vehicles. Detailed machine shop inspection procedures verify all bearing clearances before final crating for transport to maintenance hubs.

• 58X crankshaft trigger wheel communicates with modern E67 powertrain control modules without signal lag.
• Four valves per cylinder actuated by twin overhead camshafts maximize high-speed breathing capacity.
• Exhaust camshaft phaser dynamically adjusts timing overlap to broaden low-end pulling power.
• Seven cross-bolted main bearing journals hold crankshaft runout to within 0.0003 inches.
• Chevy 4.2L gerotor oil pump provides 65 PSI continuous pressure to hydraulic lifters and rod bearings.
• Multi-layer steel cylinder head gaskets prevent combustion leakage under 210 PSI cranking pressures.
• Cast iron cylinder sleeves maintain true bore roundness under severe continuous thermal cycling.
• Hydraulic roller followers minimize parasitic valvetrain drag to support commercial fuel efficiency.

Dynamic Oil Pressures Horsepower Outputs

Normal operating oil pressure maintains 22 PSI at hot idle and 55 to 65 PSI at 2,500 RPM cruise. Engine coolant temperature regulates between 192°F and 205°F through standard thermostatic flow. Power output measures 291 continuous horsepower at 6,000 RPM, providing 277 lb-ft torque at 4,800 RPM. A 10.3:1 compression ratio yields 200 to 210 PSI cranking compression. Heat rejection across radiator circuits reaches 4,300 BTU/min under Severe Commercial Fleet duty cycles across heavy regional freight corridors.

Rear Crankshaft Flange Driveline Specs

The rear crankshaft hub incorporates a 6-bolt flexplate pattern for commercial automatic transmissions. Crankshaft snout diameter is ground to 1.259 inches with precision keyways for damper installation. Dial indicators gauge crankshaft thrust endplay between 0.003 and 0.007 inches. Pilot bore fits GM commercial transmission input shafts without modification.

Engine Priming Negative Operational Boundaries

Use a pressure priming canister to charge the main oil gallery and cam phaser cavity before ignition. Fill the engine with approved 5W-30 synthetic blend oil for initial bearing film protection. Not engineered for marine salt water use, supercharger boost pressures above 5 PSI, or vehicles exceeding factory gross axle ratings.

• Inspect external oil pan seals and cooling fluid levels each shift.
• Check front accessory drive belt alignment every 50 operating hours.
• Change crankcase motor oil and spin-on lubricant filter every 5,000 miles.

Commercial Warranty Freight Crate Manifest

Backed by our 3-Year / 100,000-Mile commercial fleet warranty against defects in material and remanufacturing craftsmanship. Shipped in a heavy-duty container containing the remanufactured long block engine, high-capacity oil pump, pickup tube, complete installation gasket set, pre-lube instructions, and dyno inspection sheets.