Overview

Recently, Factors like stricter emission norms and environmental concerns have created many hurdles and adverse sentiments for the survival of diesel vehicles. However, there’s no denying that there is still a significant demand for diesel engines, particularly in large-sized SUVs and trucks. Like the Silverado HD, which has the biggest and most powerful diesel engine from Chevrolet under its hood, the L5P Duramax.

Developed by General Motors, the L5P Duramax claims the highest ever power and torque outputs in the history of its diesel engines. This full-blown performance of the 6.6 Duramax V8 diesel has made it a preferred powertrain by many for full-size heavy-duty trucks from General Motors like Chevrolet Silverado HD and GMC Sierra HD. Here, we take a quick look at how Chevrolet has managed to keep the flame of diesel supremacy alive with the 6.6-liter L5P Duramax diesel.

History Of Chevrolet L5P Duramax Engine

The history of Duramax diesel engines goes back to 2001 when General Motors launched a new family of 6.6-liter diesel engines named Duramax. DMAX, a fully-owned subsidiary of General Motors, started making Duramax engines in General Motors’ production facility in Moraine, Ohio.

Initially launched in Chevrolet and GMC heavy-duty trucks in 2001, the 6.6-liter Duramax diesel engine currently wears the L5P prefix and is the flagship powertrain for the full-size trucks from General Motors. The Chevrolet L5P Duramax was introduced in 2017 as the brand’s most powerful diesel engine ever, which was updated in 2024 with tweaked internals. With revised performance, this second-generation L5P Duramax now ranks as the most powerful Chevrolet diesel engine ever.

Which Chevrolet Vehicles Get The 6.6L V8 Duramax Engine?

The only Chevrolet vehicle that is currently available with the 6.6-liter L5P Duramax diesel engine is the full-size Silverado HD pickup truck. All the variants of Chevrolet Silverado HD – WT, Custom, LT, LTZ, ZR2, and High Country – are being offered with the 6.6 Duramax as the standard powertrain, along with the 6.6-liter V8 gas engine.

Improvements In Chevy L5P Duramax Engine: How It Is Different From Its Previous Version

Chevrolet hasn’t altered the cubic capacity and basic architecture of the L5P Duramax over its predecessor, the LML Duramax. However, there are so many tweaks to its internals that it can almost be termed an all-new engine over the engine it succeeded. Compared to the LML Duramax, which existed between 2011 and 2016, the new-generation L5P Duramax got several upgrades for enhanced performance. Following are those updates:

• An upgraded cylinder block
• A new camshaft
• More durable reciprocating assemblies
• A new turbocharger
• New fuel injectors and injection pump
• Ceramic glow plugs
• Higher oil and coolant flow rates

All these changes enhanced the performance of the vehicles, while also improving their towing capacity.

Performance Of Duramax V8 Diesel Engine: Power, Torque And Fuel-Efficiency

The first-ever iteration of the Chevrolet L5P Duramax, introduced in 2017 for Silverado HD, claimed 445 hp and 910 lb-ft, instantly becoming the most powerful Chevy diesel engine ever. However, for the 2024 update, this engine was tweaked with more internal changes to maximize performance outputs.

Result? While the power output increased to 470 hp, the torque output was even better at 975 lb-ft. While Chevrolet is not claiming any fuel efficiency figure for the Silverado HD with the L5P Duramax engine, the owners have reported up to 13-14 mpg in city conditions and up to 20-21 mpg in highway driving conditions.

Reliability Of L5P Duramax: How Many Miles Does It Last?

One of the known issues of the previous-generation LML Duramax engine for the Chevy Silverado 1500 was the poor functionality of the fuel injection pump. Many owners and internet forums have reported concerns like breakdown due to lack of lubrication in the fuel injection pump. Chevrolet addressed this issue by replacing the Bosch CP4 pump with a new Denso HP4 pump for the L5P Duramax.

Compared to its predecessor with the Bosch fuel injection pump, the new-generation Duramax V8 engine with the Denso pump became relatively more durable. The old C4 pump was known to break down due to inferior material durability, resulting in the formation of debris in the fuel lines and regulator. However, there are no such issues in the new Denso pump, making the L5P Duramax more reliable in the long run. With maintenance schedules regularly followed, owners have reported that the L5P Duramax can run hassle-free even over 350,000 miles.

Related: Are Chevy Vehicles Reliable?

Conclusion: Is The 6.6 Duramax L5P A Good Engine?

The Duramax V8 series of diesel engines was already one of the landmark engines in the US, establishing industry-best performance outputs for diesel vehicles. However, with the L5P Duramax, Chevrolet addressed all the minor concerns of the previous-generation engines while also upping its forte in performance. This new-generation Duramax L5P series engine has pushed the bars of performance even higher while also becoming more durable in the longer period of ownership. Is it a perfect match to the mammoth Chevrolet Silverado HD? You bet.

FAQs

Q1. What year Duramax is the L5P?

The L5P Duramax came in as a replacement for the LML Duramax in 2017, and continues to be available in its updated version, which was introduced in 2024. 

Q2. Is The 2024 Duramax still an L5P?

Yes, the 2024 6.6 Duramax V8 is an L5P, with the new second-generation version claiming higher power and torque outputs over its predecessor. 

Q3. Is the Duramax L5P a twin-turbo?

The L5P Duramax in Chevrolet Silverado HD is offered with a single-turbo configuration, though there are some owners who modify it with an additional turbo as an aftermarket solution. 

Q4. How long will an L5P Duramax last?

Many owners have reported that the L5P Duramax can last over 350,000 miles, provided it is maintained properly.  

Q5. Is Duramax an Isuzu engine?

The Duramax V8 is made by DMAX, which was a joint collaboration between General Motors and Isuzu. While the base engine design came from Isuzu, the rest was designed by General Motors. However, General Motors became the sole owner of DMAX in 2022, after Isuzu withdrew from DMAX.