When we launched the first generation Duramax four-cylinder turbo-diesel engines two years ago, both the 2.5-liter and 2.8-liter variants delivered best in class power and torque outputs. The new-generation, MY14 Duramax engines just raised that bar even further with unprecedented levels of output from a compact and highly-efficient construction. When we were developing the second-generation Duramax engine, outright power and torque outputs were not the main priorities.

The key to performance is efficiency—the more efficient the engine, the more powerful it will be. Better efficiency also means better reliability, economy as well as lower emission levels.

—Nicola Menarini, Global Chief Engineer, GM Powertrain

The new Duramax engine is now stronger and more durable. The 2.8L has several new parts, including a new water-cooled variable-geometry turbocharger; a new high-pressure common-rail fuel delivery system; a new Exhaust Gas Recirculation (EGR) system; a new intake manifold; a new cylinder head; a new cylinder block; a new balancer shaft unit; and a new Engine Control Module (ECM).

• 2,000 bar common rail system. The high pressure fuel pump of the second generation Duramax engine operates at pressures up to 2,000 bar, enabling increased engine efficiency.

• Water-cooled turbo. Click to enlarge.

  Turbo (2.8L). The improved variable-geometry turbo incorporates a water-cooling system in the turbine housing to reduce heat when operating at high speeds and full load. This feature extends the life of the turbo and the engine.

• EGR valve and EGR cooler. The new EGR system decreases NO_x emissions by reducing charge temperature and reducing excess levels of O₂ in the combustion chamber. The new Duramax engine uses an electric EGR valve for greater precision and a larger EGR cooler to further reduce recirculated exhaust gas temperature.

• Intake manifold with EGR valve and EGR cooler assembly. Click to enlarge.

  Intake manifold. The new engine uses an enhanced, lighter and higher efficiency intake manifold, which helps improve overall engine performance. The redesigned and improved intake manifold allows increased exhaust gas recirculation and increases air intake efficiency. The manifold, in conjunction with the new EGR system, helps reduce emissions.

• Cylinder head. An improved and redesigned cylinder head has a larger exhaust port and water passage to enhance cooling efficiency. The new engine comes with an improved oil distribution channel to enhance lubricant supply in the cylinder head. The second generation cylinder head is lighter and increases overall engine efficiency.

• Cylinder block. A new water jacket and cooling circuit design in the new cylinder block helps improve heat exchange. The new cylinder block is also lighter, which contributes to improved vehicle efficiency.

• Balance shaft unit. The new balance shaft unit reduces vibration and noise caused by crankshaft and reciprocating parts. Redesigned components inside the balancer shaft and an improved production process reduces engine vibration and noise.

• Engine control module (ECM). New software and hardware was developed by the GM engineering team for quicker response, improved accuracy and precision of overall engine control. The second generation engine offers better fuel economy, performance and lower emissions.

The new Duramax 2.8L is capable of 500 N·m (369 lb-ft) of torque at 2000 rpm (178 N·m/liter of engine capacity). Power is also increased, up to 200 hp (147 kW) for the 2.8L variant while the 2.5L now delivers 163 hp (120 kW).

Performance of the new Duramax will be matched to a re-tuned six-speed transmission to take advantage of the engine’s output characteristics while enhancing economy.

The new four-cylinder Duramax engine will be built in GM Powertrain’s facility in Rayong, Thailand, with a local content of 55 percent. In addition to being installed in the Colorado and Trailblazer slated for the Thai and Southeast Asian markets, the MY14 Duramax will also be exported to other global markets.

The US$ 200 million, 120,000-units per year GM Powertrain Thailand is the first facility to produce the Duramax four-cylinder turbo-diesel engines. The facility introduced a new engine-block line in 2012, underlining the facility as a leader in advanced powertrain manufacturing. The new block line offers the benefits of strict in-house quality control, higher local content for the Trailblazer and Colorado, and more efficient production.