L5P Duramax vs. 6.7 PowerStroke – What Engine Is Better for You?

The L5P Duramax and 6.7 PowerStroke are turbo diesel engines produced by General Motors and Ford, respectively. The two engines power heavy-duty pickup trucks and commercial-grade vehicles.

In this article, we shall briefly compare these massive engines to help you determine which one is better for you.

Key features and my opinion about the engine

• Production years:2001-now
• Average lifespan of Duramax V8:240,000-280,000 miles
• Fuel supply type:Common Rail
• Power range:250-550 hp
• Fuel efficiency:average
• Engine block material:cast-iron
• Engine reliability score:medium
• The most common problems:DPF and EGR problems, weak sensors, injectors contamination, fuel pump problems.

Key features and my opinion about the engine

• Production years:2011-2016
• Average lifespan of 6.7 Power Stroke:240,000-270,000 miles
• Fuel supply type:Common Rail
• Power range:330-475 hp
• Fuel efficiency:average
• Engine block material:cast-iron
• Engine reliability score:medium
• The most common problems:turbo problems, cooling system issues, weak sensors, CP4 pump problems.

L5P Duramax vs. 6.7 PowerStroke: Horsepower and Torque

Horsepower and torque output are the most important specs when purchasing a work truck or commercial-grade vehicle. In this category, the two engines, the L5P, and the 6.7 PowerStroke, come pretty close.

The L5P produces 445 horsepower and 910 lb-ft of torque. With these numbers, this becomes the most potent engine in the history of Duramax engines. The L5P engine features the Allison 1000 or 10-Speed Allison transmission, depending on the model year of your truck.

On the other hand, the latest 6.7 PowerStroke engine produces a peak of 475 horsepower and 1,050 lb-ft of torque, making it more powerful than the L5P.

To decide the better engine regarding power and torque, the 6.7 PowerStroke comes a little ahead of the L5P Duramax.

L5P Duramax vs. 6.7 PowerStroke: Towing Capabilities

The towing capacity of an engine greatly depends on the vehicle it powers. However, the L5P and the 6.7 PowerStroke are excellent tow machines that haul right about anything you throw at them. The towing capacity also depends on the model year of the truck you own.

For the L5P Duramax, the engine produces 445 horsepower and 910 lb-ft of torque. Although the towing capacities are not the same through the model years, General Motors improved the engine throughout to increase its towing capabilities.

The 2017 to 2019 L5P powering the GMC and Chevy HD trucks had a maximum towing capacity of 23,300 lbs. In 2020, General Motors enhanced the engine, increasing the towing capacity to 35,500 lbs. In 2021, the automaker improved the engine further to give it a maximum capacity of 36,000 lbs.

On the other hand, the 6.7 PowerStroke is a beast in its own class. If you have those hefty loads, trust any truck powered by the 6.7 PowerStroke. The engine has a Gooseneck towing capability of up to 37,000 lbs.

Various trim models haul different weight loads. Therefore, the ultimate towing capacity of your specific truck will depend on its trim. For instance, if you choose the 2022 F450 Regular cab, you will enjoy the engine's maximum towing capacity of 37,000 lbs.

L5P Duramax vs. 6.7 PowerStroke: Fuel Efficiency

Since the EPA does not run fuel mileage tests on heavy-duty trucks like the Silverado HD or the Ford Super Duty trucks, we rely on real-world tests for the fuel economy of these two engines. For example, using the Silverado HD Z71, the vehicle's onboard computer shows an average of 14 MPG driving around town and 18 MPG on the highway.

On the other hand, the Ford F-250 Super Duty powered by the 6.7 PowerStroke records an average of 14.6 MPG driving around town and 15.5 MPG when on the highway. From these numbers, you can agree that the L5P has better fuel economy than the PowerStroke.

However, it is important to note that these numbers can change depending on the trim version of your truck or the weight loaded on the truck.

L5P Duramax vs. 6.7 PowerStroke: Reliability and Maintenance

Although the reliability of an engine comes down to how well you maintain it, the L5P Duramax and the 6.7 PowerStroke are pretty reliable. If we are being fair to the automakers, we can agree that the two turbodiesels can last a lifetime with minimal repairs.

Down to the comparisons, the current L5P engine is the most reliable Duramax ever made. General Motors removed the CP4.2 fuel injection and improved a few components, including the engine block and the pistons. These enhancements made the L5P a reliable and highly capable powerhouse.

Although this is a very tuner-friendly engine, heavy modifications could harm its performance. So far, there have not been any serious complaints regarding emissions. However, you might need to flush the DEF fluid more often than expected.

The L5P engine has a life expectancy of 350,000 miles. If you adhere to the manufacturer's recommended service schedules, you might clear this mark without severe problems. Several owners have reported using their L5P-powered trucks up to 500,000 miles and beyond.

The 6.7 PowerStroke falls in the category of "not too good, not too bad." Although all engines develop problems at some point, the 6.7 PowerStroke has a bigger share of troubles than the L5P Duramax, especially the 1^st and 2^nd generations of the engine. You would be right to suspect the same issues for the 3^rd generation, but it is too early to judge.

That is not to conclude that the 6.7 PowerStroke is a horrible engine. Most problems plaguing the 6.7 PowerStroke are related to the emissions OEM equipment, which many owners choose to delete once they start showing signs of failure. Although this doesn't seem right according to the law, the 6.7 PowerStroke engine tends to run better when you delete some of these emissions systems.

The 6.7 PowerStroke also has other issues unrelated to emission systems. For example, its primary radiators tend to develop leaking problems as the engine ages.

Due to these problems, the 6.7 PowerStroke only has a life expectancy of 200,000 miles. If your truck clocks or passes this mark, you must be very good at maintenance. If you follow Ford's recommended maintenance schedule religiously, some owners have reported having clocked 300,000 miles without any worrying problems.

Do These Two Engines Have a Common Problem?

The L5P and the 6.7 PowerStroke are excellent power machines. They are the best engines for your heavy-duty truck. However, despite the praises, these engines have their fair share of troubles that may make you want to think twice before buying one.

Besides the problems each engine experiences on its own, one problem has proved so notorious that it plagues both engines. The two engines are famous for notorious fuel injection problems.

The injection pump is the breaking point of all 6.7 PowerStroke engines. The pump is famous for breaking down due to metallic surfaces coming into contact. The fuel injection system also fails on the 6.7 PowerStroke because of contaminations that may affect the injectors and pressure regulators. These failures can cause more problems that will be costly to repair.

The L5P engine is also quite notorious for failed fuel injectors. Many owners opt to replace the original injectors with aftermarket parts as soon as the injectors fail for the first time. Even the team at General Motors knows that their original L5P injectors have design flaws that cause them to crack. Although they reportedly fixed the flaw, fuel injector failure is still a concern with many L5P Duramax engines.

The L5P injectors also have fault ball seats that cause the injectors to leak over time. On the L5P-powered trucks, fuel injector failure leads to loss of power, poor or rough idling, and excessive smoke.

Conclusion

With such a competitive race between these two massive turbodiesel engines, it is evident that you have to put other factors into consideration when choosing which heavy-duty truck to purchase. The numbers could help you decide. However, from the data we have shared in this article, you know you will not lose or gain much by choosing one engine over the other.

To make a buying decision, you have to consider the price, comfort, convenience, size of the truck, and other factors. While one engine might fall behind in power and torque output, it may take the lead in reliability and ease of maintenance.

Do your due diligence, and shop around. Visit showrooms and dealerships online and in-store. Ensure you have exhausted your research before buying an L5P-powered HD truck or one with the 6.7 PowerStroke engine.