Everything You Wanted to Know About Duramax Diesel Engines but Were Afraid to Ask

March 11th, 2022 by

A Duramax logo is shown in close up.

In 2001, the Duramax engine kicked off a renaissance for diesel trucks. More efficient and more powerful than its gasoline-powered counterparts, the Duramax diesel has pushed the Chevy Silverado to new heights of performance and capability. Because the trends of the automotive industry tend to be implemented by multiple manufacturers, the diesel engine’s comeback is one that’s been remarkable. If you’ve ever been out on the McCluskey Chevrolet lot, you may have noticed a few diesel-powered pickups, and you might have been curious about them and how they work. The truth is, even used diesel trucks can provide a great deal. How? We’re about to find out. Strap yourselves in; we’re about to give you the crash course on everything you need to know about Duramax engines.

The Early Days and the LB7 (2001-2004)

For fans of science fiction, the year 2001 holds a unique place in the mythology of author Arthur C. Clarke. While the real 2001 didn’t feature a computer named Hal, or even a monolith responsible for evolution, it did feature the first generation of the Duramax engine. A 6.6L turbocharged diesel engine was made available for both the GMC Sierra HD and Chevrolet Silverado HD, and it didn’t take long for drivers to take notice of its unique capabilities. Its 300 horsepower and 520 lb-ft of torque were certainly impressive numbers at the start of the millennia, and the fact that both could be reached at low RPMs meant that the engine could maintain high performance while working less. But as impressive as this engine was, the first Duramax still had plenty of room for improvement.

Kicking It Into Gear With the LLY and LBZ (2004-2007)

The LB7 would be discontinued by 2004. Taking its place that year was the improved LLY 6.6L V8. Depending on the year, the second-generation Duramax diesel pumped out up to an impressive 310 horsepower and 605 lb-ft of torque. Thanks to improved turbocharger design, the motor also proved to be more responsive than its predecessor, a flaw that had been associated with diesel-powered engines of the past. While the Silverado HD and Sierra HD would both benefit from the motor in question, the Duramax spread its wings as it were and could also be found in the Hummer H1 for the 2006 model year.

2006 would also see the arrival of the new kid on the block, the LBZ. The third incarnation of the Duramax again amped up the performance for both the Silverado HD and Sierra HD and once more showed the innovative talents of GM. Both trucks could churn out 360 horsepower and an impressive 650 lb-ft of torque. However, the LBZ never quite got the proper chance to live up to its full potential. Due to stricter emission guidelines, the engine would be discontinued by 2007. The LBZ was the last Duramax diesel that did not have extensive emissions control systems.

Go Forth and Conquer with the LMM (2007-2010)

GM went back to the drawing board for the fourth incarnation of the 6.6L Duramax. With creating fewer emissions in mind, GM went about making a motor that was more friendly to the environment without eliminating the high performance that customers had grown accustomed to. While the improvements in performance were minimal (365 horsepower and 660 lb-ft of torque), it was a milestone in innovation that performance could increase while adhering to the emissions standards set forth by the government.

The new emissions standards were met through the inclusion of a diesel particulate filter (DPF) in the exhaust. The DPF catches toxic particulate and then burns it off during the engine’s regeneration cycles. Although this system does limit the potential of the engine slight and can lead to issues if it is not properly maintained, it significantly reduces pollution compared to earlier diesel engines. And while the LMM does have a DPF, it does not require the use of diesel exhaust fluid (DEF), which can make it simpler to maintain.

A grey 2012 Chevy Silverado LTZ is show angled right.

Innovation, Determination, and the LML (2011-2016)

A wise man once said, “In times of peril, you don’t fall upon your sword.” GM’s tireless efforts to not cave to pressure and stick to its guns resulted in the fifth-generation Duramax, known as the LML. The newest incarnation of the highly functional diesel-fueled engine didn’t lack in either performance or emissions reductions. Thanks to GM’s efforts, the new Duramax had lowered emissions by an astounding 63%. A remarkable feat to be accomplished in such a short amount of time. With over half of the engine manufactured from new components previously unused on earlier incarnations of the Duramax, it seemed that the rebirth of the diesel engine had received its own rebirth.

If the attention that GM placed on being more environmentally friendly was a sign of its willingness to adapt, then the improvements in performance showed that the company had never lost sight of what drivers were looking for from a diesel truck. The LML generated 397 horsepower and an even more astounding 765 lb-ft of torque. This large increase in power was the result of several innovations, including a new common-rail fuel system with piezo injectors and a variable geometry turbocharger. These improvements allowed for greater optimization of the engine, squeezing out more power than ever before.

L5P and the Rebirth of Perfection (2017-Present)

It’s been remarked that you can’t reinvent the wheel. You can, however, perfect the diesel engine. GM proved that fact to be true when it introduced the L5P. For the first time, a 10-speed transmission was made available for the Duramax, which now reached new heights of impressive performance. With no less than 445 horsepower and 910 lb-ft of torque, the L5P demonstrated that a diesel engine could produce incredible power while still meeting stringent emissions standards. This mighty engine allows the Chevy Silverado HD to tow up to an unbelievable 36,000 pounds and is a sought-after powertrain in any used truck.

A grey 2017 Chevy Silverado 1500 is shown from the side parked in front of a fence.

LM2: The Baby Duramax (2018-Present)

For the drivers of smaller trucks such as the Chevrolet Silverado 1500, diesel power was made available to them in the form of a 3.0L inline-6 Duramax. While the full-size Duramax uses the more common V8 configuration, the inline-6 configuration is renowned for its smooth power delivery and reduced vibration. Generating 277 horsepower and 460 lb-ft of torque, this smaller version of the big bad wolf delivers all the benefits of diesel-fueled efficiency on a slightly smaller scale. A used Silverado 1500 diesel can offer a fuel economy of up to 26 MPG combined and a towing capacity of up to 13,300 pounds.

Go Diesel at McCluskey Chevrolet!

GM has a long history of building revolutionary engines, and the Duramax is only one chapter. No matter what engine is under the hood of a used Chevy or GMC truck, you can rest assured that it will provide you with years of reliable service. If you want to experience what these engines offer for yourself, simply come visit McCluskey Chevrolet to take some of our used diesel trucks out for a test drive. You’ll soon see why every generation of the Duramax engine has its own fanbase of loyal supporters.

Posted in Used Diesel Trucks