TH661116LMLSOALBHD Tow Haul HD Series Speed Of Air Long Block (Standard/Auto)

Features:

• 5-year / 160,000 km warranty
• Built for up to 900 HP
• Ideal for towing 500-750 HP loads
• Includes all Street and Tow/Haul upgrades
• Wagler forged connecting rods
• Wager Stage 1 alternate firing camshaft
• Balanced rotating assembly
• Heavy-duty flexplate
• ATI performance dampener
• Callies Compstar crankshaft
• Precision-machined to factory specifications
• Complete top-end gasket kit included

Take Your Duramax To A Whole New Level

If you are looking for an engine that can handle serious power and still keep up with everyday driving, the DFC Diesel Tow Haul HD Series Speed Of Air Long Block is built to deliver. Designed for the 2011-2016 GM Silverado/Sierra 2500HD and 3500HD, this long block is perfect for the diesel owner who tows heavy loads but wants the ability to push well beyond factory horsepower limits. Rated for up to 900 HP at the flywheel, it is just as comfortable pulling a trailer at 500-750 HP as it is laying down big numbers on the dyno. This build includes the strongest components DFC offers, like Wagler forged connecting rods, a Wager Stage 1 alternate firing camshaft, and a balanced rotating assembly. Heavy-duty additions like the ATI dampener, Callies Compstar crankshaft, and HD flexplate give you peace of mind when you are pushing your truck to its limits. It is backed by a 5-year, 160,000 km warranty, so you can enjoy every pull, climb, and haul without second guessing your investment. Whether you are hauling for work or pushing your build for fun, this long block has the muscle and the engineering to handle it.

Built With Premium Components For Extreme Power And Reliability

The DFC Diesel TH661116LMLSOALBHD Tow Haul HD Series Long Block is engineered for serious power while maintaining street and towing usability. Every engine starts with a professionally machined block, bored for the next oversized piston using advanced equipment to ensure precise tolerances. The Wagler forged connecting rods provide unmatched bottom-end strength, while the Wager Stage 1 alternate firing camshaft enhances torque delivery and reduces stress on the crankshaft under load. A balanced rotating assembly works with the Callies Compstar crankshaft, ATI dampener, and HD flexplate to keep the engine smooth and stable even at higher power levels. This model also carries over all upgrades from the Street Series and Tow/Haul Series, including Total Seal gapless piston rings, heavy-duty valvetrain components, and ARP or OptiTorque head studs. Rockers and pushrods are preset to factory specifications, and a complete top-end gasket kit is included for a clean and efficient installation. Designed to support up to 900 HP while excelling in the 500-750 HP towing range, this engine offers the strength, precision, and dependability needed for demanding builds.

Fits: 2011, 2012, 2013, 2014, 2015, 2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LML/LGH

Notes:

• Confirm fitment for 2011-2016 LML/LGH Duramax trucks.
• Rated up to 900 HP at the flywheel.
• Optimized for towing in the 500-750 HP range.
• Includes all Street and Tow/Haul Series upgrades.
• Equipped with Wagler forged connecting rods.
• Includes Wager Stage 1 alternate firing camshaft.
• Balanced rotating assembly, HD flexplate, and ATI dampener.
• Features a Callies Compstar crankshaft for added strength.
• Long block excludes external accessories and sensors.
• Comes with a complete top-end gasket kit and preset valvetrain.
• ARP or OptiTorque head studs supplied based on availability.
• Backed by a 5-year / 160,000 km warranty; follow break-in and core return requirements.

Street Series vs Tow/Haul vs Tow/Haul HD

• Street Series: Ideal for daily driving, light work, and diesel enthusiasts. Focuses on reliability upgrades over stock, with head stud and sealing improvements.

• Tow/Haul Series: All Street upgrades plus added performance parts for higher load and towing power. Supports builds up to ~700 HP.

• Tow/Haul HD Series: The most robust option. Adds heavy-duty internals like Wagler rods and a balanced rotating assembly for 800+ HP capability.

Standard/Auto vs Standard vs Auto

• Standard/Auto: Compatible with both manual and automatic transmissions. Offers the most flexibility.

• Standard: Built specifically for manual transmission configurations.

• Auto: Built specifically for automatic transmission setups.