DFC Diesel TH661116LMLSOALB Tow Haul Series Speed Of Air Long Block (Standard/Auto) | 2011-2016 GM/Chevrolet 2500HD/3500HD 6.6L Duramax LML/LGH

Features:

• 5-year / 160,000 km warranty
• Built for towing up to 500 HP
• Includes all Street Series upgrades
• Stage 2 performance camshaft installed
• Mahle Motorsports heavy-duty pistons
• Manton heavy-duty pushrods
• Heavy-duty valve springs
• ARP or OptiTorque head studs
• Total Seal gapless piston rings
• Added crankshaft dowels for stability
• Precision-machined to factory specifications
• Complete top-end gasket kit included

Built To Pull Hard And Keep On Going

When the job calls for serious towing power and all-day reliability, the DFC Diesel Tow Haul Series Speed Of Air Long Block for the 2011-2016 GM or Chevrolet 2500HD and 3500HD is ready to step up. This engine is purpose-built for heavy haulers, RV owners, and anyone who needs consistent strength on the road or at the jobsite. Rated for up to 500 horsepower at the flywheel, it is more than capable of moving large loads without breaking a sweat. The Tow Haul Series includes every upgrade found in the Street Series plus enhancements built to handle the extra stress that comes with towing and performance driving. Mahle Motorsports heavy-duty pistons and Manton heavy-duty pushrods are designed to withstand extreme cylinder pressures, while a Stage 2 performance camshaft delivers smoother, more responsive power. ARP or OptiTorque head studs keep everything sealed tight, even under high boost. And with a 5-year, 160,000 km warranty, you can hit the road knowing your investment is backed by one of the strongest guarantees in the industry.

Engineered With Upgrades That Go Beyond Stock Limits

The DFC Diesel TH661116LMLSOALB Tow Haul Series Long Block is precision-built to exceed OEM durability while delivering noticeable performance gains. Each block is machined to exact factory tolerances using advanced Rottler equipment and bored for the next oversized piston, ensuring a perfect fit and long service life. The Mahle Motorsports HD pistons provide improved strength and heat resistance for heavy towing situations, while the Stage 2 performance camshaft optimizes airflow for better torque and throttle response. Manton HD pushrods and HD valve springs work together to keep the valvetrain stable at higher power levels. ARP or OptiTorque head studs maintain a reliable seal under extreme boost and load conditions, and added crankshaft dowels for the harmonic balancer and trigger gear assembly increase stability in high-stress environments. The engine also comes with Total Seal gapless piston rings for maximum compression retention and reduced blow-by. With a complete top-end gasket kit included and rockers and pushrods preset to spec, installation is straightforward and ready to deliver dependable power from day one.

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

Notes:

• Confirm fitment for 2011-2016 LML/LGH models.
• Rated up to 500 HP at flywheel.
• Tow/Haul includes Street Series upgrades.
• Speed Of Air long block designation applies.
• Long block excludes external accessories and sensors.
• Includes complete top-end gasket kit.
• Rockers and pushrods arrive preset to spec.
• ARP or OptiTorque head studs based on availability.
• Stage 2 cam, HD pistons, HD valvetrain included.
• Machined for oversize pistons; verify reused parts.
• Freight shipping and core return typically required.
• Follow break-in steps and register warranty.

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.