Duramax 6.6L Engine

We offer three kinds of 6.6L Duramax Engine:

Street Series | Tow/Haul Series | Tow/Haul HD Series


DFC Diesel Rebuilders prides itself in being the highest quality product on the market. This is why we can back our engines with a 5 year 160,000km warranty that we stand behind.

Our engines have been re-manufactured to factory specs using all new industry recognized name brand parts that meet and exceed OEM specifications. The block has been professionally machined and bored for use with the next over-sized piston.

All New OEM or equivalent pistons, rings, and gaskets are used to ensure quality and consistency of our engines. Our Re-manufactured Cylinder Heads have all new seats, guides, valves, and stem seals as well as being resurfaced and magnafluxed.

Short Block Engines include:

  • Front cover with seal
  • Rear cover with main seal
  • Oil pan
  • All internal components
  • Complete gasket kit for installation
  • Important installation instructions

Long Block Engine Include:
  • Complete short block assembly and gaskets, plus cylinder head
  • All rockers/pushrods preset to factory specs
  • Complete Top End gasket kit to finish install

All remanufactured engines are serviced with Rottler CNC machining, which guarantees high quality results.

To learn more about Rottler’s innovative, industry leading machines please visit: www.rottlermfg.com


Our Street Series of engines are DFC’s flagship product. Built for work trucks, daily drivers and the diesel enthusiast in mind these engines are a vast improvement from stock as they contain important upgrades to common problem areas. Street Series are Long Blocks with ARP series 2000 head studs or OptiTorque head studs depending on availability.



  • Most comprehensive 5 year / 160,000 km (100,000 mi) warranty in North America.
  • All engines come standard with Total Seal gapless piston rings.
  • DFC custom EDM doweled oil pump gear.
  • Woodruff keyed camshaft
  • Street series, Tow/Haul series and Tow/Haul HD series engines available.
  • Machined with some of the most advanced Rottler machining equipment in North America.
  • Improved gasket sealing methods in common leakage areas.
  • All NEW pistons, rings, bearings, gaskets, seals, valves, springs, stem seals and cast guides standard in every engine.


The DFC Diesel Tow/Haul Series engine comes standard with all the upgrades found in the Street Series model as well as several enhancements to make this engine perfect for towing, hauling and performance applications up to 500 HP. DFC long block assembly including Total Seal gapless piston rings.


Contains all upgrades of the Street Series and includes;

  • DFC long block assembly
  • ARP series 2000 head studs or OptiTorque head studs depending on availability
  • Stage 2 Performance camshaft
  • Mahle Motorsports HD pistons
  • Manton HD push rods
  • HD valve springs
  • Added dowels to crankshaft for harmonic balancer and trigger gear assembly
  • LB7 include screw in injector cups

Built for 500HP
*Rated HP is measured at flywheel same as factory engine HP ratings


The DFC Diesel Tow/Haul HD Series was built for the enthusiast that wants to be capable of up to 900 HP but that will regularly drive on the street and tow trailers between 500 and 750 HP. This model comes equipped with all the features of the Street and Tow/Haul Series but adds a set of Wagler Forged connecting rods, Wager stage 1 alternate firing camshaft, balanced rotating assembly, HD flexplate, ATI dampener and Callies Compstar crankshaft.


Includes all the upgrades of the Street Series & Tow/Haul Series as well as includes;

  • Wagler Forged connecting rods
  • Wager stage 1 alternate firing camshaft
  • Balanced rotating assembly
  • HD flexplate
  • ATI dampener
  • Callies Compstar crankshaft

Built for 900HP
*Rated HP is measured at flywheel same as factory engine HP ratings

DFC can build a very durable and robust combination for your specific needs and all still backed with a 5 year 160,000km (100,000mi) parts and labor warranty. Make us your only choice for Duramax diesel engines in North America.

Tow/Haul and Tow/Haul HD series engines still come backed with a 5 year 160,000 km (100,000 mi) warranty however are considered a severe duty application and require more frequent service intervals as stated in warranty manual supplement for warranty coverage to be considered.


Comes standard with 5 yr 160,000 km (100,000 mi) parts and labor warranty


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Custom EDM keyed oil pump preventing oil pressure loss


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Cylinder blocks are blueprinted to tighter tolerances than OEM specifications using our Rottler F69 ATC


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Oil Pump

All DFC 6.6 Duramax engines feature an EDM doweled oil pump shaft with a hardened dowel installed locating the gear to the oil pump shaft preventing slipping and the subsequent oil pressure loss.

Head Gasket Sealing

Some model years of Duramax engines are more susceptible to premature head gasket failure. To reduce the chance of this all DFC long blocks come with new head bolts, revised torque sequences and digitally recorded torque values to ensure reliability.

Valve Springs

Instead of just testing old springs and reusing like most remanufactures DFC installs brand new SBI valve springs that are still tested for proper spring pressure on every cylinder head we rebuild.

Cast Guides

Common industry practice is to check guide clearance and if within specification, not replace. DFC considers this practice unacceptable and installs new cast SBI guides in every cylinder head we remanufacture.

Torque Specs

These engines use many torque to yield fasteners that require bolt “stretch” to maintain adequate clamp loads. In addition to not just following the OEM procedures for tightening sequence our assembly technicians record the achieved torque load through use of digital torque wrenches ensuring no fastener will come loose over time.



Our Rottler equipment allows us to remanufacture the Duramax engine’s to tighter than OEM specifications resulting in a longer lasting more efficient engine assembly.

Core Criteria

Ensuring every engine is built to the same high quality standards as the next DFC is very strict on what is remanufactured rejecting components that require considerable “restoring” to acceptable specifications.


DFC installs new valves from MAHLE/Clevite or SBI in every cylinder head we remanufacture. Most companies will re-grind and install used again.

Weighed Rotating Assemblies

Our production engines are typically matched with near identical weight piston and connecting rod assemblies giving our customers a smoother running and quieter engine.