Diesel Engine and GM Diesel History

Volume 3 Issue 3 - Diesel Articles

If you are not new to the world of the Diesel engine, you are probably familiar with some of its history dating back to the turn of the Twentieth Century when Rudolf Diesel patented, tested and began to license his design for a self-igniting engine. Let’s take a look at some of the highlights of that history and then look in more detail at the Diesel engine's application by GM since the early 1980s.

In 1897, Rudolf Diesel successfully fired the first engine that was able to ignite fuel without the introduction of a spark. By compressing the fuel/air mixture in the cylinder so that it heated to above the fuel’s ignition point threshold, the mixture self-ignited (auto-ignited) without the need for spark plugs. The design, introduced a few years prior to this testing, signaled the passing of the age of steam engines, though steam-powered ships were built as late as the 1980s. For example, the FairSky was the last major passenger ship built with steam engines in 1984 and the Queen Elizabeth 2 was converted from oil-fired steam engines to Diesel engines only in 1986.


In 1912, the MS Selandia was the first ocean-going ship powered exclusive;y by a Diesel engine.

It only took about a year from Diesel’s initial testing in August 1897 for him to become a millionaire from his invention. If we set his worth at $1 million, it would be equivalent to nearly $27 million in purchasing power today. Diesel’s design gradually found its way into manufacturing, electrical, ships, planes, tanks and more. We’ll look at some of the highlights; you can see more at this historical timeline.

  • 1902-1910 – 82 stationary diesel engines had been produced by the German company, MAN.
  • 1905 – Turbochargers and intercoolers were introduced by the Swiss company, Büchl.
  • 1909 – The prechamber with a hemispherical combustion chamber was developed by Prosper L’Orange with the help of Benz.
  • 1912 – The Danish built the first ocean-going ship exclusively powered by a diesel engine, MS Selandia. The first locomotive with a diesel engine also appeared.
  • 1913 – U.S. Navy submarines use New London Ship and Engine Company (NELSECO) diesel units. During this year, Rudolf Diesel died mysteriously when he crossed the English Channel on the SS Dresden. A badly decomposed body with personal items belonging to him was found 10 days later. Some people suggested suicide while others have felt that there were business interests that stood to benefit and believed he was murdered.
  • 1919 – Prosper L’Orange obtained a patent on a prechamber insert and made a needle injection nozzle. First diesel engine from Cummins.
  • 1923 – The first truck with a diesel engine made by MAN, Benz and Daimler is tested.
  • 1929 – Cummins installs a diesel engine he built into a Packard and drives it from Indiana to the 1929 Auto show in New York City on $1.39 worth of diesel fuel. The car was banned from the show but still received popular support from those in attendance.
  • 1946 – Cummins patents the common rail diesel system. This is the fuel delivery system used in modern turbo diesels.
  • 1954 – Volvo mass produces the turbo diesel truck.
  • 1977 – Mercedes produces the first passenger car turbo-diesels (Mercedes 300 SD).
  • 1986 – Bosch introduces Electronic Diesel Control (EDC) in the BMW 524tD.
  • 2002 – Gale Banks builds a street-driven Dodge Dakota pickup with a 735 HP diesel engine and sets an FIA land speed record as the world’s fastest pickup truck at Bonneville Salt Flats with a one-way run of 222 MPH and a two-way average of 217 MPH.

So, there are some highlights of the history of the diesel engine with a focus on its application in on-the-road vehicles. Now let’s look at how the diesel has been specifically introduced into the GM pickup market over the last three decades.

Detroit Diesel

The Detroit Diesel company was been formed by GM in 1937 and became a major provider of two-stroke diesel engines for World War II. In 1944 alone, the company produced 62,000 engines that found their way into applications such as landing craft, tanks, road building equipment and standby generators. In 1970, GM merged Detroit Diesel with its Allison Division to form Detroit Diesel Allison Division. In 1988, GM reformed the division into its own Detroit Diesel Company. Today, the company is actually owned not by GM but by Daimler AG which acquired it from DaimlerChrysler (that, in turn, acquired it from GM in 2000) when that company re-split into its original two companies.

Detroit Diesel produced both the 6.2L and 6.5L. GM introduced the 6.2L in 1982 and continued production through 1993. The engine was installed in the following vehicles:

  • 1982-1993 Chevrolet/GMC C/K
  • 1992-1993 AM General Hummer H1
  • 198x-1993 AM General HMMWV
  • GM version of the CUCV
  • 1982-93 Chevrolet Van


The 6.2L Dietroit Diesel appeared in several body types including the early Hummers.

6.2L Specifications

  • Displacement: 6.2L / 379 cubic inches
  • Bore x Stroke: 3.98 × 3.80 in (101 × 97 mm)
  • Block / Head: Cast iron / Cast iron
  • Aspiration: Natural
  • Valvetrain: OHV 2-V
  • Compression: 21.5:1
  • Injection: Indirect
  • Horsepower / Torque (1982): 130 HP (97 kW) @ 3,600 RPM / 240 lb-ft (325 Nm) @ 2000 RPM
  • Horsepower / Torque (1993): 143 HP (107 kW) @ 3,600 RPM / 257 lb-ft (348 Nm) @ 2000 RPM
  • Horsepower / Torque (army): 165 HP (123 kW) @ 3,600 RPM / 330 lb-ft (447 Nm) @ 2100 RPM
  • Max RPM: 3600
  • Idle RPM: 650 + or – 25

6.5L Diesel

GM began introducing the 6.5L diesel in 1992 and started phasing out the 6.2L. The 6.2L had been naturally aspirated but almost all of the 6.5L diesels were equipped with turbochargers. For the first two years, the 6.5L employed a mechanical fuel injection pump, a feature that some drivers still prefer over the electronic fuel injection that was introduced in 1994. In the middle of 1996, GM introduced a marginally improved cooling system that itself can be significantly improved upon with Heath Diesel’s Heavy Duty Cooling System Upgrade.

Bonneville Trip Photos 137.jpg

Bill Heath built a 6.5L land speed racer that can also be used to drive around town.

Here are the vehicles the 6.5L diesel found its way into along with the engine’s specifications:

  • 1994-1999 Chevy Blazer/ 2-door Tahoe / GMC Yukon
  • 1992-1999 Chevrolet Suburban / GMC Suburban
  • 1992-1999 Chevrolet and GMC C/K
  • 2000 Chevrolet and GMC C/K 2500 & 3500
  • 2001 Chevrolet and GMC C/K 3500
  • 1994-2004 AM General Hummer H1
  • 1994-present AM General HMMWV


  • Displacement: 6.5L / 397 cu in
  • Bore x Stroke: 4.06 x 3.82 inches
  • Block / Head: Cast iron / Cast iron
  • Aspiration: Turbocharged; Also available naturally aspirated.
  • Valvetrain: OHV 2-V
  • Compression: GM Early 21.3:1, GM Late 20.3:1, AMG/GEP Marine 18:1
  • Injection: Indirect
  • Power / Torque (lowest): 180 HP (134 kW) @ 3400 RPM / 360 lb-ft (488 Nm) @ 1700 RPM
  • Power / Torque (highest): 215 HP (160 kW) @ 3200 RPM / 440 lb-ft (597 Nm) @ 1800 RPM
  • Max RPM: 3400

Looking through the lens of today’s powerful Duramax it is understandable how these engines can be viewed as underpowered. They were produced at a time when the industry was focused much more on fuel economy than it was on power. Still, Bill Heath and others have discovered that the 6.5L Detroit Diesel engine can be transformed into a reliable and relatively powerful work engine with some straightforward modifications. You can read more about those improvements in Suburban Renewal, which covers 6.5L general reliability and power modifications, and Making the Grade, which looks specifically at 6.5L towing improvements. These articles look honestly at the 6.5L diesel’s shortcomings including the pump-mounted-driver (PMD), fuel injectors and computer programming as well as other issues and present relatively inexpensive solutions.

New Millennium, New GM Diesel

The frustrations encountered with the stock 6.2 and 6.5 diesel engines became well known to diesel enthusiasts so that in 1996 GM possessed only three percent of the diesel-powered pickup truck market. That figure has improved ten times in response to GM’s commitment at the time to start from scratch instead of simply redesigning the 6.5 diesel.

Jim Kerekes, the chief diesel engineer at GM Powertrain, shares some of the details of what would become the Duramax in The Duramax Diesel 6600 Story. GM decided to use its partner, Isuzu, to lead the design of the new engine that originally was slated for introduction to North America in 2003. After high level talks, the date was pushed up to 2000 in order to coincide with GM’s new pickup truck model. The GM and Isuzu engineering teams worked in tandem in the US and Japan “around the clock” in order to facilitate the aggressive schedule.

By September 1998, engine design had progressed enough that the newly formed DMAX Ltd. between Isuzu (60%) and GM (40%) was building a new engine production plant in Moraine, OH. The engine boasted the introduction of a common rail fuel system to the North American pickup market as well as pilot injection that resulted in a quieter engine and much-improved fuel economy.

Kerekes writes: “The new engine was targeted to meet Best-in-Class-Performance for power and torque. In order to transfer the 300 HP and 520 foot pounds of torque to the truck’s wheels, a new 5-speed automatic transmission was developed.” This would become the Allison Transmission 1000 series that was designed to work hand-in-glove with the new engine.

It took only 37 months to develop the new 6.6L engine, dubbed “Duramax” by the GM marketing team, and it appeared in the 2001 GM pickup truck models in 2000. Again, Kerekes writes that “the engine was an immediate success bringing up GM’s market share from three percent to 30 percent in the HD Diesel pick-up truck market.”

Duramax Iterations

Since its introduction a decade ago, the Duramax engine has gone through several engine models. We’ll take a look at the specifications for each. Joel Paynton and Michael Patton have documented issues with – as well as provided solutions for – “thermal feedback” in the LLY edition. GM addressed this overheating issue in the LLY’s successor, the LBZ.

LB7 (2001 to Mid-2004)


This 2004 Chevy Silverado featured the Duramax LBZ engine.

  • Key Features: common-rail fuel system, 32-valves, aluminum heads
  • Key Issues: leaking fuel injectors that caused fuel dilution in oil, severe overheating


  • Engine type: 6599 cc (402.7 cu in) V8 turbo
  • Bore x Stroke: 4.06 in (103.1 mm) x 3.90 in (99.1 mm)
  • Block / Head: Cast gray iron / Cast aluminum
  • Aspiration: Turbocharged & Intercooled
  • Valvetrain: OHV 4-V
  • Compression: 17.5:1
  • Injection: Direct; Bosch High Pressure Common-rail
  • Power / Torque: 300 BHP (220 kW) @ 3100RPM / 520 lb-ft (705 Nm) @1800 RPM
  • LLY (Mid-2004 to 2005)
  • Key Changes: variable geometry vane turbocharger, exhaust gas recirculation (EGR) valve, improved maintenance access to fuel injectors
  • Key Issues: thermal feedback caused by a narrow air intake and no cold air intake
  • Specification changes from LB7: Power / Torque: 310 BHP (230 kW) @3000RPM / 590 lb-ft (800 Nm) @1600 RPM


In 2006, GM introduced a new engine design that initially retained the LLY model. Then in 2007 GM made no mechanical changes to the engine but redubbed it the LBZ. So while there are mechanical differences between a 2005 LLY and a 2007 LBZ, there are no such differences between a 2006 LLY and the LBZ.

There were a number of improvements with the LBZ:

  • Air intake improved to reduce overheating issues in previous LLY model
  • Revised piston design helps lower compression ratio to 16.8:1 from 17.5:1
  • Maximum injection pressure increased from 23,000 PSI to more than 26,000 PSI
  • Revised variable-geometry turbocharger is aerodynamically more efficient to help deliver smooth and immediate response and lower emissions
  • Specification changes from 2004-2005 LLY: LLY 300 BHP (220 kW) @3000 605 lb-ft (820 Nm) @1600 3200 / LBZ 360 BHP (270 kW) @3200 650 lb-ft (881 Nm) @1600 3450


This Pony Xpress motor home employs a 2006 LLY Duramax engine under the hood.

Since there were no mechanical changes in between the latter LLY and the LBZ, you may be asking yourself where the LBZ found the extra power and torque. The answer? GM beefed up the tune in the LBZ’s computer.


The LMM arrived in 2007 as GM’s answer to ever-increasing emissions regulations. Joel Paynton focuses on these emission controls in Duramax Fuel System for Dummies as well as their negative effect on fuel economy. The diesel particulate filter used raw diesel fuel as part of a regeneration cycle that burns off built up soot particles. This solution was probably rushed by necessity in response to Federal regulations that were thrown onto the industry. The good news is that the later generation LML engine deals with the issue more methodically contributing to the LML marked fuel economy improvement.


A 2007 Duramax LMM with fifth wheel in tow.

Specification changes:

  • Compression: 15.8:1
  • Injection: Bosch High Pressure Common Rail with CP3.3 Injection Pump
  • Power / Torque: 365 BHP (272 kW) @3200 RPM / 660 lb-ft (895 Nm) @1600 RPM


For an in depth look at the 2011 LML, check out Joel Paynton’s review

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