How much HP does a 2016 6.6 Duramax have?

The 2016 Duramax 6.6-liter V8 is rated at 397 horsepower and 765 lb-ft of torque in standard heavy-duty pickups such as the Chevrolet Silverado 2500HD and GMC Sierra 2500/3500. Output can vary slightly by drivetrain and emission calibration, but 397 hp is the commonly cited figure for that year.

The Duramax 6.6L engine lineage includes multiple generations with different power figures. This article focuses on the 2016 model year and shows how its horsepower compares to later Duramax versions.

2016 Duramax power figure

The 2016 Duramax is part of the LML family and used in heavy-duty trucks; the following numbers reflect the standard SAE net output published for 2011–2016 models:

SAE net horsepower and torque explained

Power and torque figures for diesel engines are published as SAE net values, representing output with the engine installed in the vehicle and with standard equipment and emissions controls in place. Torque is likewise measured as net torque.

• Horsepower: 397 hp @ 3,000 rpm


• Torque: 765 lb-ft @ 1,600 rpm

Conclusion: For 2016 Silverado/Sierra 2500HD/3500HD trucks, the 6.6L Duramax delivers about 397 hp and 765 lb-ft of torque in standard configuration.

How it stacks up against later generations

To put the 2016 figure in context, GM increased Duramax output in the next generation (the L5P) starting with 2017 models:

• Horsepower: 445 hp


• Torque: 910 lb-ft

Conclusion: The 2016 Duramax is lower in horsepower and torque compared with the post-2016 L5P generation, which introduced a notable power uplift for the Duramax lineup.

Summary

The 2016 Duramax 6.6L V8 provides 397 horsepower and 765 lb-ft of torque in typical HD pickups. Later generations (2017 onward) increased to about 445 hp and 910 lb-ft, reflecting a major power upgrade. For exact figures on a specific vehicle, check the window sticker or VIN-based documentation.

How much horsepower does a 2016 LML Duramax have?

The stock 2016 LML Duramax has 397 horsepower and 765 lb-ft of torque. With performance tuning, the horsepower can be increased, with levels of +30 HP, +60 HP, +100 HP, and even up to +150-160 HP or more depending on modifications like a lift pump, exhaust, and turbo upgrades. For example, one tuning package offers up to +160 HP, and another can reach up to 500 wheel horsepower or more with supporting modifications. 
Stock vs. Modified

Item	Stock	Modified
Horsepower	397 hp	Up to 500+ hp with tuning and supporting modifications
Torque	765 lb-ft	Up to 950+ lb-ft with tuning
Tuning Levels	—	+30 HP, +60 HP, +100 HP, +135 HP, +160 HP or more

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Important Considerations for Modification

• Supporting modifications: Some tuning levels require additional parts, such as a lift pump to prevent damage to the stock CP4.2 injection pump. 
• Transmission limitations: The stock Allison transmission has a power capacity, and exceeding approximately 450 wheel horsepower may require transmission tuning or upgrades to maintain reliability. 
• Other factors: Upgrading the turbo, injectors, and installing a CP3 pump can significantly increase horsepower beyond what stock components can handle. 

Note: Horsepower figures for modified engines are based on specific tuning and part combinations. Results may vary depending on the specific setup.

Is the 2016 6.6 Duramax a good engine?

The 2016 6.6L Duramax (LML) is considered a good engine for its robust performance and reliability, but it has a significant known weakness: the CP4 high-pressure fuel pump, which can fail and cause expensive, cascading damage to the fuel system. This is a well-documented issue, and potential owners should be aware of it, as preventative measures like using high-quality fuel or installing a CP3 retrofit kit can help mitigate the risk.
 
Positive aspects

• Performance: Known for strong performance and good power delivery. 
• Cold-weather starting: Features advanced glow plugs that provide quick starts in cold temperatures, sometimes without a block heater. 
• Fuel economy: Achieves decent highway mileage for its class, outperforming the gas V8 options. 
• Reliability: With proper maintenance, these engines can be very reliable and last for a long time. The Allison 1000 transmission that is paired with it has a strong reputation for being reliable. 

Potential issues

• CP4 fuel pump failure: This is the most significant problem. The CP4 high-pressure fuel pump is prone to failure, and when it does, it can send metal shavings through the entire fuel system, leading to costly repairs that often include the injectors.
• Costly repairs: A CP4 failure is a serious issue. The repair cost is high because it requires replacing the pump and often the injectors as well. 

What to do if you own or are considering one

• Address the CP4 issue: Consider a preventative upgrade to a CP3 fuel pump, which is more reliable.
• Use quality fuel: Always use high-quality diesel fuel to help protect the fuel system.
• Change fuel filters regularly: This is a key preventative maintenance step to ensure the fuel system stays clean. 

What year to avoid 6.6 Duramax?

Years to avoid for the 6.6L Duramax include 2004.5–2005 (LLY) due to overheating and 2011–2016 (LML) because of the high-pressure fuel pump (CP4) failure, which can destroy the entire fuel system. Other problematic years are 2001–2004 (LB7) for injector issues and 2025–present (LZ0) due to thrust bearing problems.
 
This video explains the common problems and reliability of the Duramax LML: 58s8020 AutomotiveYouTube · Feb 14, 2023
Engine years to avoid

• LB7 (2001–2004): Prone to injector failures, which are expensive to fix. 
• LLY (2004.5–2005): Known for overheating issues, especially when towing. 
• LML (2011–2016): The CP4 fuel pump is a significant weak point, and its failure can be catastrophic, leading to costly repairs for the entire fuel system. These models also have complex emissions systems. 
• LZ0 (2025–Present): Newer 3.0L versions have reported thrust bearing failures, excessive crankshaft play, and resulting oil pressure issues. See this YouTube video for more details. 

Years with potential issues

• LBZ (2006–2007): While considered reliable, some years have had turbo and wiring harness issues, though these are generally manageable. 
• L5P (2017–Present): While generally good, some models may have issues with the MAP sensor or other emissions components. See this YouTube video for more details. 

Recommended years

• LBZ (2006–2007): Often considered the most reliable year due to its powerful performance and less complex emissions systems.
• L5P (2017–Present): A modern, powerful engine, but some models may require extra maintenance for emissions systems. 

Is a 6.7 Cummins better than a 6.6 Duramax?

The Cummins 6.7L is generally favored for higher torque and towing capacity, while the Duramax 6.6L often has a slight edge in horsepower and a reputation for a smoother, quieter ride. The Cummins is an inline-6 engine, and the Duramax is a V8. Performance can vary by specific model year, with the latest iterations of each engine being very competitive.
 
This video compares the power, torque, and other specifications of Cummins, Duramax, and Power Stroke engines: 1mTruck MasterYouTube · Dec 2, 2020
Cummins 6.7L 

• Configuration: Inline-6 
• Torque: Higher torque, with the High Output version reaching up to 1,075 lb-ft, making it ideal for heavy towing. 
• Horsepower: Generally lower horsepower than the Duramax, but still powerful. 
• Driving feel: Often described as having a strong, low-end pull, feeling less phased by heavy loads at lower RPMs. 
• Engine history: A long-established brand with over 100 years of history, used in Ram trucks since 1989. 

This video provides an overview of the performance of the 2024 Silverado Duramax and 2023 High Output Cummins: 58sBen HardyYouTube · Apr 8, 2023
Duramax 6.6L

• Configuration: V8 
• Horsepower: Generally higher horsepower, with some models reaching up to 470 horsepower. 
• Torque: Lower torque than the Cummins, but still very capable. 
• Driving feel: Often praised for a smoother, quieter ride, with a driving feel that can feel quicker at wide-open throttle. 
• Engine history: Has been used in GM vehicles since 2001. 

Which one to choose?

• Choose the Cummins 6.7L if: Your priority is the highest possible towing and hauling capability, and you value the strong, low-end torque for heavy loads. 
• Choose the Duramax 6.6L if: You want more horsepower for quicker acceleration and prefer a smoother, quieter, and more refined driving experience.