Help Us Get to 1,000!




Trucks Submitted

Don't Miss Out on Our Gen-Y Hitch GIVEAWAY!

6.6L LB7 Duramax Specifications And Information

2001 was a huge year for GM lovers across the United States. Not only was 2001 the start of the Duramax engine, but also the famous Allison 1000 Transmission. This first Duramax engine mated with GM trucks was coined the LB7 Duramax. While today, all Duramax trucks are paired with the Allison transmission, LB7 Duramax trucks also had an available ZF 6-speed manual transmission option. Producing 235-300 horsepower and 500-520 lb/ft of torque, the LB7 Duramax was a beast. It was a huge success that ultimately led to the creation of other Duramax engines including the LBZ, LMM, LML, and L5P. To help those of you who currently own an LB7, or those who want to purchase one, we’ve compiled a pretty massive list of LB7 Duramax specs. Find our 6.6L LB7 Duramax Specifications chart below.

6.6L LB7 Duramax Specifications Chart

Manufactured Years:2001-2004
Engine Design: 6.6L 90-Degree V8 Turbocharged Diesel
Transmission:5-Speed Auto Allison Transmission
Vin Identification:
(8th Digit)
Displacement:6.6 Liters or 403 Cubic Inches
Engine Weight:835 Lbs
Bore:4.055″ or 103 mm
Stroke:3.897″ or 99 mm
Block Material:Cast Iron
Cylinder Head:Cast Aluminum
Crankshaft:Forged Steel
Connecting Rods:Forged Steel
Compression Ratio:17.5:1
Firing Order:1-2-7-8-4-5-6-3
Turbocharger/Air:IHI RHG6 Wastegated Turbocharger And
Fuel Injection:Direct Injection High Pressure Common Rail
with Bosch CP3 Injection Pump
Valvetrain:Overhead Valve (OHV) 4 Valves per cylinder (32V)
Engine Oil Capacity:10 Quarts With Filter
Cooling System
Allison 1000 Automatic Transmission : 20.3 Quarts
ZF 6-Speed Manual Transmission: 20.5 Quarts
Fuel Tank Size:26 Gallons
Max Engine Speed:3,250 RPM
Horsepower:235-300 horsepower
Torque:500-520 lb/ft of torque

Important Tech Info LB7 Duramax

LB7 Emissions

The 2001 LB7 Duramax was the first diesel engine in this class to utilize common rail technology. Common Rail tech wasn’t used until the 3rd Generation 5.9L Cummins in Ram trucks, or the 6.4L Powerstroke in Ford trucks. LB7 Duramax trucks also came before diesel emissions, so there is no DEF, DPF, or SCR here! You could just slap on a straight-pipe exhaust with no repercussions! No tuning needed!

LB7 Fuel System Issues

Although the lack of emissions greatly improved the reliability of these trucks, the original injectors actually had significant issues. So many issues in fact, that GM recalled the trucks, replaced the original injectors, and extended the warranty on injectors to 200,000 miles. Many of the issues found their roots in the Fuel Filtration design. Fuel reaching the injectors was not properly filtered. Aftermarket fuel systems like a Fass or Air Dog can greatly improve reliability and help solve common LB7 Duramax problems.

Aluminum Heads

Unlike Ford’s Powerstroke or the Cummins engine in Ram trucks, GM used Aluminum heads on their Duramax engine. Many questioned their reliability initially as Ford and Dodge both used Cast Iron heads. To this day, however, GM uses the Cast Aluminum heads even in their L5P duramax. GM proved they could provide a lighter and equally as reliable head design using cast aluminum.

LB7 Duramax Steering & Suspension

As with other Duramax trucks, the LB7 Duramax utilizes an independent front suspension (IFS) design. The IFS system provides a very comfortable ride, however, it is also much more expensive to modify, and much less sturdy than the stock straight-axle design of Ford or Ram. The design will hold up relatively fine if a stock suspension, wheel, and tire set-up is used. Aftermarket suspensions, bigger tires, and bigger wheels will all drastically decrease the lifetime of front-end parts. If you own an LB7 or will be purchasing one, we highly recommend taking a look at the Kryptonite or Cognito suspension and steering kits.

Horsepower & Torque

2001-2003235 Horsepower @ 2,700 Rpm500 LB/FT @ 1,600 Rpm
2004300 Horsepower @ 3,100 Rpm520 Lb/Ft @ 1,800 Rpm

LB7 Duramax Towing Capacity

How can you list 6.6L LB7 Duramax Specifications without tow ratings! Find our LB7 Duramax towing capacity chart below! For more complete towing information, refer to your truck’s owners manual. The LB7 Duramax Tow ratings below are the highest numbers the trucks are capable of. Actual tow ratings vary according bed length, cab size, and whether the truck features single rear wheels or if it is a dually.

Tow Rating:
5th Wheel
Tow Rating
2001-200412,000 Lbs15,800 Lbs9,200 Lbs22,000 lbs3964 lbs

Learn More About the LB7 Duramax

Want to learn more about the LB7 Duramax? Check out our other resources by clicking on one of the links below.

We Live & Breath Diesel.

Want to learn more about the latest insights in the diesel industry? Signup for our newsletter and stay up to date on the top trending topics!


Founder of Diesel Resource and a complete diesel head. Has a little bit of problem buying too many trucks. Learn more about him by checking out his truck.