Next Gen Duramax Speculation

Upgraded Duramax Spied, Rumored 2017 MY Release

Published February 1st, 2016

The Duramax LML, the latest generation of the Duramax 6600 engine platform, was introduced for the 2011 model year for GMC Sierra and Chevrolet Silverado HD pickups. Rated at 397 horsepower and 765 lb-ft of torque, the engine features the complex exhaust aftertreatment system that has become standard within the sector. Going strong on its fifth straight model year without a significant revision or upgrade, many are starting to ponder what the LML’s replacement will look.

Face it, the current Duramax and GMC/Chevrolet HD platforms are more than enough truck, so do we really need more power and capability? The current 3500 model pickups from GM, for example, are rated to tow up to 20,000 lbs conventional and 23,200 lbs 5th wheel (or gooseneck). Majority of owners are very unlikely to take full advantage of these ratings and at nearly 400 horsepower, the Duramax has more than enough grunt to get the job done. The age-old expression “If it ain’t broke, don’t fix it” certainly supports GM’s current position in the sector.

On the other hand, the diesel sector is largely marketed with extreme prejudice on power and capability. If being number 1 in these categories suggests a more attractive truck to potential buyers, than the Duramax is indeed in need of a revamp. To put it into perspective, here’s where GM stacks up against its competitors:



2016 Ford F-350*

2016 Ram 3500

2016 GMC/Chevrolet 3500 HD

% Difference**


6.7L Power Stroke

6.7L Cummins H.O.

6.6L Duramax LML



440 hp @ 2,800 rpm

385 hp @ 2,800 rpm

397 hp @ 3,000 rpm



860 lb-ft @ 1,600 rpm

900 lb-ft @ 1,700 rpm

765 lb-ft @ 1,600 rpm



up to 6,682 lbs

up to 6,720 lbs

up to 5,587 lbs


Conventional Tow***:

up to 19,000 lbs

up to 18,000 lbs

up to 20,000 lbs


5th Wheel Tow***:

up to 26,500 lbs

up to 31,210

up to 23,200 lbs


* Ford F-450 omitted from comparison, max gooseneck tow rated at 31,200 lbs using SAE J2807 standards.
** Calculated percent difference between GMC/Chevrolet HD and nearest competitor per category.
*** Maximum payload and towing for diesel equipped models only - all gas engines excluded.


While Ford and Ram have continued to battle it out for “Best-in-class” positions over recent years, GM has sat comfortably on its current platform, which only leads in maximum conventional towing and by a relatively low margin. Furthermore, a completely revised Ford Super Duty will enter the picture for the 2017 model year, featuring an aluminum body and likely more powerful 6.7L Power Stroke diesel.

So what can we expect from the next generation Duramax diesel? The Duramax revamp will need to include increased power output without negatively impacting fuel economy. In fact, a more fuel efficient engine would greatly increase the platform’s desirability. Revising the engine won’t be without its challenges, including:

• Balancing fuel economy and power output. The Duramax has fallen far behind both the Cummins and Power Stroke in the torque department. We're speculating the next gen Duramax will yield somewhere between 450 horsepower and 850 - 900 lb-ft of torque; anything less and the Duramax will continue to fall short of the competition.

• GM's biggest hardship will be maintaining stringent emission standards while squeezing more power and fuel economy from the Duramax. Despite making it this far, the 6600 Duramax platform is 15 years old. You can expect the next Duramax to feature the same restrictive exhaust aftertreatment found on the current LML, which requires diesel exhaust fluid.

• Throttle response has become an important selling point in the diesel sector. The new Duramax is likely to wield an improved turbocharger to match the air demands of a more powerful engine without sacrificing quick spooling characteristics.

Will GM go clean slate on the new Duramax? Unlikely, although we speculate significant changes and the next gen engine will likely differ significantly from the current LML. Both Chevrolet and GMC pickups have SAE J2807 tow ratings, and a more powerful engine may greatly impact their ability to increase max allowable capability on their HD trucks. Little is known about the upcoming Duramax, including its introduction date. At this point, everything is purely speculation.