Every generation of Duramax engines brought something new and improved to the table. The L5P is proving itself to be the best Duramax engine until now. It is utilized in Silverado HD and GMC Sierra HD, and you need to know what year the L5P came out before buying the car.
So, what year did the L5P come out? It was introduced in 2017. in Chevy and GMC trucks. It is a major upgrade to a generation-old LML. It has a completely revamped fuel system, a new turbocharger, and, from 2020—a new transmission. The pistons are also improved, and their work life is prolonged. It is a powerful engine that has a stock of 445 horsepower and 910 lb-ft of torque.
But what makes this engine the favorite out of the Duramax bunch? How does it handle on the road? Stay with us and learn!
Timeline of L5P
The GM knew they delivered a high-quality product, but they didn’t stop there. Every year they issued some improvements. The most drastic one is the re-haul of the transmission in 2020.
L5P Duramax Was Introduced
The L5P is introduced in 2017 and it instantly became a favorite. Improved driving capabilities and reliability are key factors in its popularity. This engine addressed some older Duramax engine issues which the drivers pointed to.
The fuel system is replaced, and a stock lift pump is added. This resolved the problem of fuel flow when the stock components were tuned up. The New Denso fuel pump and injectors were a clear hit, allowing the engine to get a lot of power and torque.
The cooling system is improved, allowing the engine and the new turbocharger to receive enough cool air. Another noteworthy improvement is the new and improved glow plugs.
Minor Improvements Of Styling & Tech in 2018
This new engine propelled the sale of GMC and Chevrolet, which led to several improvements. Trucks made in 2018 and got several new color options, a Denali grill design, and the tire pressure system alert. All models with a cargo box have the standard rear-view camera.
Refinement of Technology and Trim in 2021
In 2021 a bed view camera and an EZ lift tailgate were added in LT models. Also, Apple CarPlay and Android Auto systems are added. The most notable improvement in 2020. was the introduction of the new Automatic Allison transmission.
The older 6-speed transmission made completely by Allison was replaced with 10-speed Allison transmission. The production process is moved to GM, while Allison engineers are responsible for monitoring the development and production.
This 10-speed Allison transmission offers improved towing capabilities, better fuel economy, and high reliability.
Is A L5P Reliable?
The L5P follows the tradition of previous Duramax engines, which are known for their reliability. There are reports that owners had no major problems before hitting the 300k mark. With proper and regular maintenance, these engines can go past 400k miles without problems. This is making this Duramax engine more than an incredible engine.
The performance and characteristics are also improved. When compared to LML, the L5P offers an increase in power from 397 hp to 445hp and torque from 765 lb/ft to 910 lb/ft.
To achieve this, the engineers needed to do a major overhaul of several engine systems.
- Upgrade of the turbocharger. Up to L5P, Duramax engines used the Garrett turbocharger, which used the Variable Vane design. They are controlled and actuated via oil pressure. The new Borg Warner turbochargers are electronically controlled and actuated with improved turbocharger response. They are using the Variable Geometry Design, which proved to be more efficient and reliable. This new turbocharger has 11 blades and a bit larger inducer than the Garett turbos. The BW turbocharger has a maximum boost pressure of 28 psi, which significantly improves LML-s 22 psi. This turbocharger also has exhaust braking capabilities like the LML, just a bit better
- Fuel system overhaul. The L5P still uses the common rail direct-injection fuel system. Up until L5P the supplier of this system was Bosch, but now they switched to Denso. That includes replacing the old Bosch CP4.2 with the Denso HP4 fuel injection pump. Also, this engine is supplied with a built-in lift pump. That helps in resolving most of the fuel injection pump issues. With the lift pump, some of the workload is taken off the injection pump. Earlier, the injection pump needed to pull the fuel out of the tank and pressurize the fuel for the fuel injectors. This was especially an issue if the stock injectors were replaced. Any additional need for fuel was a problem, and with the lift pump, this problem is resolved. With these improvements, the stock fuel pump can support up to 800 hp, but only with improved injectors
- New fuel injectors. Like the rest of the Bosch components, old Bosch fuel injectors are replaced with ones made by Denso. These injectors are less complex but offer more. They are easier to maintain and can also support up to seven fuel delivery events per combustion cycle. These injectors produce 20% better fuel flow when compared to old Bosch units
- New intake system. GM included a fully-functional hood scoop intake system to improve airflow volume. With this new system, around 60% of the air is provided through the hood scoop, and the rest comes through the intake system that sits within the front fender. The engine is this way supplied with more cold air than before, thus improving power, reliability, and emission control. Also, if one air route is blocked the air can still reach the engine
- Improved oil and coolant flow rates. Cooling capacity is improved by 50% with a high-capacity engine oil cooler. Also, piston jets produce 50% better cooling capacity with a dedicated turbocharger oil line.
Check Out All About the L5P Duramax Engine! | 4 Common Problems:
Engine Specs of L5P
Since it is a major upgrade when compared to the older Duramax engines, it is good to know its specifications.
| Engine design | 90-Degree V8 Turbocharged Diesel engine |
| Displacement | 6.6L |
| Engine Block Material | Cast Iron |
| Cylinder Head Material | Cast Aluminum |
| Bore | 4.055″ (103mm) |
| Stroke | 3.897″ (99mm) |
| Compression ratio | 16.0:1 |
| Firing Order | 1 – 2 – 7 – 8 – 4 – 5 – 6 – 3 |
| Valvetrain | 32 Valves (4 Valves Per Cylinder) OHV or Overhead Valve |
| Turbocharger | Borg Warner Variable Geometry Turbocharger |
| Horsepower | 445 HP At 2800 RPM |
| Torque | 910 lb/ft At 1600 RPM |
| Fuel System | Common Rail Direct-Injection Fuel System |
| Fuel Type | B20 Biodiesel or Ultra Low Sulfur Diesel |
| Maximum Powered Speed | 3450 RPM |
| Maximum Braking Speed | 4800 RPM |
| Transmission | 2017-2019 Allison 1000 6-speed automatic 2020- now Allison 1000 10-speed Allison |
| Emission Control Systems | Cooled Exhaust Gas Recirculation (EGR), Selective Catalytic Reduction (SCR), Diesel Particulate Filter (DPF), intake throttle |
Towing Capacity of An L5P
The first models with L5P were made in 2017 and 2020. They have a towing capacity of 11.485 lbs. The truck remains quiet even when towing the maximum load. This is an important feature because diesel engines tend to be loud, which can become annoying over time.
Both Chevy and GMC trucks undergo an overhaul in 2020. The body style has changed, and new towing technologies are utilized. This allowed a towing of heavy loads like no other older Duramax trucks. These trucks can now tow 35,500 lbs, which is a 50% increase.
Fuel Efficiency of An L5P
The most reliable way to know the fuel economy is by following information on the onboard computer. In the case of an L5P, it reports 13-14 MPG in a city drive, while on a highway the figure goes to 17-18. When compared to the previous Duramax engine, it is not a visible improvement.
Performance Upgrades For Additional Power On for Your L5P
If you are thinking about boosting your engine, you are not the first. From the beginning, Duramax engines were great bases for tuning. They can pull out massive amounts of power and torque.
S&B Cold Air Intake
Cold air intake is one of the most popular and effective ways to tune up your engine. S&B intake is an enclosed air box that still features the factory ram air intake. These improved intakes will keep the temperatures lower, thanks to better air density. Also, more cool air will enter the engine. That way, the engine can produce more power and with better efficiency.
This modification can get you an additional 10-15 hp, and it will allow the turbocharger to work better. Cold air intake is all around good way to tune up the truck.
MBRP Exhaust
The stock exhaust nozzle on an L5P is 2.85″ which drastically reduces the airflow at the tailpipe. There are several exhaust systems from MBPR that can improve this situation. You can choose between massive 4″ or 5″ DPF back exhausts that will improve the airflow.
They will also reduce the exhaust temperature by 10 to 15%. These diesel performance exhausts will also boost the power of the engine and will improve the fuel economy.
Transmission tuning
The Allison 1000 transmission is a big limiting factor when tuning any Duramax engine. The stock transmission runs at 80psi of line pressure, which is not great. This stock transmission can handle up to 550 WHP.
If you want to add more power than that, you will need to think about adding EPC Solenoid Fooler. It will allow the transmission to run at 200psi of line pressure constantly.
Upgrade of the Turbocharger
Although the new Borg Warner turbocharger is a huge upgrade, it still has limitations. From this turbo, you can expect a maximum of 550 WHP. If you want more than that, you can try out the S-300 or S-400 fixed geometry turbochargers from Borg Warner.
If you want to know how to make the L5P turbo louder, you can learn about it from our article that focuses on this topic.
FAQs
What year is best for an L5P Duramax?
The main difference between L5P made before and after 2020. is in the transmission. Older L5P engines are using proven 6-speed automatic Allison 1000 transmission. Some drivers will rather stick with older but proven components than switch to a new, modern 10-speed transmission. Besides that, you cannot make a wrong choice.
How much mileage does an L5P get?
With proper regular maintenance, the L5P can easily hit the 300k miles mark. It is important to change the oil and filters regularly and to use quality fuel.
How Long Does an L5P Last?
The L5P is a relatively young engine, so it is still too early to tell. Some drivers have L5P engines with more than 500k miles on the clock. These engines are still working well. Only time will tell if there will be some problems. But, from the look of things, these engines will be able to last a long time.
Final Considerations
The development of Duramax engines started in 2001. When we look at the L5P we see massive improvements and technological advancements. Today, the L5P is known as one of the best diesel engines that can be used for almost anything. You can use these trucks for towing, drag racing, or casual highway driving.
With the L5P, you get power and reliability and think about emission issues. With regular maintenance, you can rely on this engine to keep you going for many years.
