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6.6L L5P Duramax Specifications And Information

6.6L L5P Duramax Specifications, Information, and Resources!

L5P Specs And Information: 2017+ Chevy HD & GMC HD Diesel trucks

2017 L5P Duramax

GM released their 6.6L L5P Duramax in the Chevrolet Silverado HD and GMC Sierra HDs in 2017. The new L5P Duramax was by far, the most capable duramax to date, producing 445 horsepower and 910 lb/ft of torque in stock form. Similar to the LML, the L5P utilizes the same 6.6L displacement. The engine itself is vastly different however, with numerous big changes that resulted in an increase in 48 horsepower and 145 lb/ft of torque over its LML predecessor. Changes included a Borgwerner Variable Geometry Turbocharger, the addition of an in-tank lift pump, and a fully-functional hood scoop. A 6-speed Allison automatic transmission was also used until 2020. The new 2020 L5P Duramax in Chevy Silverado HD and GMC Sierra HD Duramax trucks gained a new 10-speed automatic Allison transmission. For a full breakdown of 6.6L L5P Duramax specifications, see the chart below.

L5P Duramax Specifications Chart (2017+)

Manufactured Years:2017-2020
Engine Design:90-Degree V8 Turbocharged Diesel
Transmission:2017-2019: Allison 1000 6-Speed Automatic
2020+: Allison 10L1000 10-Speed Automatic
6.6 Liters or 403 Cubic Inches
Bore:4.055″ or 103 mm
Stroke:3.897″ or 99 mm
Block Material:Cast Iron
Cylinder Head
Cast Aluminum
Intake Manifold:Cast Nodular Iron
Crankshaft:Forged Steel
Connecting Rods:Iron
Compression Ratio:16.0:1
Firing Order:1-2-7-8-4-5-6-3
Turbocharger/Air:BorgWarner Variable Geometry Turbocharger
Fuel Injection:Direct Injection, Denso High Pressure
Common Rail with 29,000 Max PSI
Injectors: New Denso G4S Gen III Solenoid Style
capable of 7 injections per combustion sequence
Valvetrain:32 Valve (4 Valves per cylinder) OHV or Overhead
Engine Oil Capacity:10 quarts or 9.5 Liters
DEF Fluid Capacity:7 Gallons
Cooling System
31.4 Quarts or 29.72 Liters
Fuel:B20 Biodiesel Blend or Ultra Low Sulfur Diesel
Fuel Tank Size:36 Gallons Standard
Max Engine Speed:3450 RPM
Max Braking Speed:4800 RPM
Horsepower:445 Horsepower At 2800 RPM
Torque:910 lb/ft at 1600 RPM

L5P Duramax Information

Between 2017 and 2019, the GM Heavy Duty trucks equipped with the L5P Duramax engine look almost identical to the LML Duramax. The main way to differentiate the two trucks by only looking at the exterior is by the hood scoop. In 2020, Chevrolet and GMC both released their respective updated Heavy Duty body styles. While the horsepower and torque numbers remained the same, max tow capacity was increased tremendously. Other convenient changes to the L5P Duramax in 2020 including a relocated DEF tank and DEF fill location and new bed steps to access the front of your truck bed.

L5P Duramax Uncrackable ECM/TCM

One thing that was clear almost immediately was the complexity of the ECM used in the new L5P Duramax trucks. It took literally multiple years for the trucks to be tuned and unlike other diesel trucks, there are no plug-and-play options. To add custom tunes to your L5P Duramax, the ECM and TCM have to be swapped with a modified version capable of receiving tuners. At this moment, HP Tuners is the only available software that can be used to tune the trucks after an ECM swap. Multiple companies are creating the tunes themselves, and up to 600 horsepower is being achieved on emissions-present tuning! While the numbers are really impressive, so is the price. Custom tuning and an ECM/TCM swap can cost upwards of $5,000.

L5P Tuning Options

If you’re not looking for custom tuning for your L5P Duramax, there are currently a handful of tuning options you can use to increase power on your L5P. You can use the Banks L5P Derringer without removing and replacing your ECM and TCM. At around $500, you can make up to 61 additional horsepower, and 112 lb/ft of torque. As with all Banks products, you can rest assured knowing the products have been tested thoroughly before they are ever released. Another L5P Duramax tuning option is the Edge Pulsar. Edge claims gains of up to 90 horsepower and 156 lb-ft of torque. This option is also much easier to install, simply plugging in to the ECM. It can still be tricky to do by yourself, so have a friend help you or visit a shop and have them do it!

Mechanical Improvements Made To The L5P in 2017

  • Stronger, Cast Iron Block & Improved Cylinder Heads
  • Re-designed reciprocating and rotating assembly
  • New Single-Cooler EGR system that includes integrated bypass
  • New Variable Geometry Turbo capable of 28 psi & Offering improved exhaust braking.
  • Two-piece Oil Pan helps reduce noise and vibration.
  • Integrated Oil Cooler with 50% greater capacity than previous design.
  • Larger diameter crankshaft
  • Solenoid Injectors support seven fuel delivery events per combustion events.
  • Venturi Jet Drain Oil Separator
  • New Ceramic Glow plugs
  • Updated Allison 1000 6-speed Transmission
  • New torque converter

L5P Duramax Changes in 2020

2020 Chevrolet Silverado 2500 HD Custom

Many L5P Duramax specifications were changed GM made major steps to the technology aspects of their trucks in 2020. Both the 2020 GMC Sierra HD and the Silverado HD will be available with over 15 new camera views, new trailering technology, and an available PTO (Power Take Off) option. 2020 GM Heavy Duty trucks will also be larger in every aspect. They’re longer, taller, and more spacious than previous Duramax trucks. Crew Cabs gained an additional three inches of leg-room in crew cab models. Our favorite change GM made in 2020 is the addition of the new DuraBed truck box.

The DuraBed

Perhaps the most useful change GM made in 2020 is the new Durabed. New GM Heavy Duty trucks will have an increased bed length to 6’9″ on standard bed lengths and retain a 8′ long bed configuration. Both the larger, standard bed and the long bed will gain box length and max box volume however. Cargo is easier to lift into the bed as box lift-in height and overall height have been decreased. Up to 12 tow-hooks are available in the bed for your use to secure cargo. An optional 120 volt power outlet is available for all bed applications. Other noteworthy Durabed features include new side-panel bed steps capable of supporting 500 lbs, the corner steps integrated into the rear bumper, and a power up/down tailgate available on higher trim models. For specific L5P Duramax specifications on the new Durabed, take a look at the chart below.

L5P Duramax DuraBed Specifications

8′ Bed

Box Floor Length:97.8 inches98.3 inches
Box Height:21.2 inches21 inches
Box Width Between
Wheel Housings:
51 inches50.6 inches
Max Box Volume:76.4 cu. feet83.5 cu. feet
Box Lift-in Height:39.6 inches38.8 inches

Standard 6’9″ Box

Box Floor Length:78.8 inches82.2 inches
Box Height:21.1 inches21 inches
Box Width Between
Wheel Housings:
51 inches51.9 inches
Max Box Volume:61 cu. feet69.6 cu feet
Box Lift-in Height:39.8 inches38.9 inches

2020 L5P Mechanical Changes

  • New 10L1000 10-Speed Automatic Allison Transmission
  • 52% Increase in Max Towing to 35,500 Lbs when properly equipped.
  • Relocated DEF tank and relocated DEF fill location. DEF will no longer be added under the hood. It has been moved to the gas cap.
  • “Beefier” Front & Rear axles.
  • 11.5″ Ring Gears on 2500HD models and 12″ Ring Gears on 3500HD models.
  • 30% Larger Diameter Prop Shafts
  • New 28″ Diameter Variable-Speed Cooling Fan that is 2.5X Larger than previous models.
2020 L5P Duramax Engine
2020 L5P Duramax Engine

L5P Towing Capacity

2020 Chevrolet Silverado 2500 HD High Country

With 445 horsepower and 910 lb/ft of torque, the L5P Duramax is capable of towing just about anything you can throw at it. Tow capacity isn’t the same throughout the L5P model years however, as Chevrolet made a major stride in 2020! To provide our readers with more L5P Duramax specifications, we created the chart below to display max towing capacities. Actual tow capacity on your Duramax may differ according to cab configuration, bed length, and whether your truck is 2wd or 4wd.

Year:Max Tow
2017-201923,300 lbs31,300 lbs
202035,500 lbs43,500 lbs

Want to learn more about the L5P Duramax?

Check out our other posts about the L5P below!

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