Industrial Injection LLY Duramax Stage 2 Long Block Engine (2004.5-2005)

Take your 2004.5–2005 LLY Duramax to the next level with the Industrial Injection Stage 2 Long Block Engine. Designed for high-horsepower street trucks, drag racing, sled pulling, and competition applications, this engine package is built to handle serious power while maintaining the durability and reliability that Industrial Injection engines are known for.

Every Stage 2 Long Block is precision machined, balanced, blueprinted, and assembled using premium performance components. Combined with Industrial Injection's fully CNC Ported & Polished Cylinder Heads, this engine is engineered to maximize airflow, increase horsepower potential, and provide the durability required for demanding performance applications.

Key Features

Engine Features

• Balanced and blueprinted rotating assembly
• Sim tested short block
• Industrial Injection X Series coated, chamfered, and de-lipped pistons
• Balanced and keyed OEM Duramax crankshaft
• 14mm Gorilla Girdle with ARP main studs
• Wagler HD forged connecting rods
• Industrial Injection keyed billet alternate firing camshaft
• ATI Super Damper
• Billet flexplate
• Pinned oil pump
• New water pump
• New oil pickup tube
• Stock oil pan
• Built for high-performance and competition use
• Optional billet crankshaft upgrade available

Cylinder Head Features

• Fully CNC ported and polished cylinder heads
• Precision machined using a 5-axis CNC cylinder head porting machine
• CAD/CAM software-developed port design
• Diamond honed valve guides
• Unshrouded valves for increased airflow
• High-strength alloy, heat-treated iron-based valve guides
• Premium nickel-based, non-magnetic valve seat inserts
• Multi-angle valve job
• 130 lb valve springs installed
• Fully assembled and ready for performance use

Stage 2 Performance Engine Construction

The Industrial Injection Stage 2 Long Block is designed for enthusiasts who demand more than a stock replacement engine. Every rotating assembly is balanced and blueprinted to ensure smooth operation and maximum durability under high horsepower conditions.

Industrial Injection X Series pistons provide enhanced strength and durability, while Wagler HD forged connecting rods and the 14mm Gorilla Girdle help reinforce the bottom end against extreme cylinder pressures. The keyed crankshaft, keyed billet alternate firing camshaft, pinned oil pump, ATI Super Damper, and billet flexplate work together to create a foundation capable of handling serious horsepower and competition use.

The included Ported & Polished Cylinder Heads are CNC machined using Industrial Injection's advanced 5-axis porting technology. This process dramatically improves airflow consistency and cylinder filling, helping support increased horsepower, improved throttle response, and greater overall engine efficiency.

Each engine is simulation tested and subjected to rigorous quality control procedures before leaving our facility.

What's Included

• Fully assembled LLY Duramax Stage 2 long block
• CNC Ported & Polished cylinder heads
• Industrial Injection X Series pistons
• Balanced and keyed OEM Duramax crankshaft
• Wagler HD forged connecting rods
• 14mm Gorilla Girdle
• ARP main studs
• Industrial Injection keyed billet alternate firing camshaft
• ATI Super Damper
• Billet flexplate
• Pinned oil pump
• New water pump
• New oil pickup tube
• Stock oil pan
• 130 lb valve springs

Not Included

• Additional assembly gaskets
• Fuel system components
• Turbocharger components
• Injectors
• Exhaust manifolds
• Engine accessories
• Break-in oil

Vehicle Fitment

2004.5–2005 GM Duramax LLY 6.6L

• Chevrolet Silverado 2500HD
• Chevrolet Silverado 3500HD
• GMC Sierra 2500HD
• GMC Sierra 3500HD

Why Choose the Industrial Injection Stage 2 Long Block?

• Built for high-horsepower street and competition applications
• Fully CNC Ported & Polished cylinder heads included
• Reinforced bottom end with forged rods and Gorilla Girdle
• Premium performance components throughout
• Precision balanced and blueprinted rotating assembly
• Billet alternate firing camshaft included
• Increased airflow and horsepower potential
• Proven Industrial Injection engine-building expertise
• Designed to withstand extreme power levels and demanding conditions
• Thoroughly tested and quality inspected before shipment

Break-In Recommendation

For optimal engine break-in and long-term performance, Industrial Injection recommends using Driven Racing Oil (Joe Gibbs) Break-In Oil during the first 300–500 miles of operation. Break-in oil is not included with the engine.