Two factors reign supreme for heavy-duty truck owners: torque and durability. For 2011, that bar has been raised with the new Duramax 6.6L turbo diesel V-8, which debuts on the Chevrolet Silverado 2500HD and 3500HD launching this summer.
The 2011 Duramax diesel brings significantly more torque and higher horsepower ratings and improved fuel efficiency. Structurally the engine features internal changes that enhance strength and durability. Functionally it also has a new integrated engine braking system. And as reported earlier this week, the engine has B20 biodiesel capability.
“Building on a proven architecture and knowing that our 2011 engine operates within the same boundary conditions let us confidently offer a product that takes performance and fuel economy to the next level,” said Gary Arvan, Duramax chief engineer.
The original Duramax turbo diesel earned its reputation for durability and led the industry with first-in-class common rail fuel injection and aluminum heads with a six-bolt-per-cylinder design. Those attributes formed the foundation for the 2011 engine, with digital modeling and simulation tools used to raise the Duramax’s power and durability benchmarks. It is expected to produce significantly more torque and horsepower than the previous engine, while delivering greater strength and durability.
The internal elements that help enhance strength and durability include:
The new Duramax 6.6L improves on an already low-noise reputation with double-pilot injection, a strengthened block and, in some conditions, lower rail pressure, contributing to a nearly 30-percent improvement in noise at the engine level. A new 30,000-psi (2,000 bar) piezo-actuated fuel injection system – capable of operating on ASTM grade B20 biodiesel – ensures more precise fuel delivery, improving emission performance and playing a crucial role in reducing high-speed noise, vibration and harshness.
The new Duramax 6.6L helps boosts towing capacity of the Silverado HD trucks to a maximum of 20,000 pounds (9,072 kg), which is best in class. Power and cooling improvements, along with improvements to the truck chassis, were key elements in boosting the towing rating.
The Duramax 6.6L’s variable vane geometry turbocharger and new Allison 1000 transmission make downhill towing less stressful, too, with the addition of a new engine braking system. The feature creates added backpressure in the exhaust, resulting in negative torque during deceleration and downhill driving, enhancing driver control and prolonging brake pad life.
Significantly, all of the Duramax 6.6L’s improvements in power and towing capability don’t come at the cost of fuel economy. Already respected for its efficiency, the new Duramax turbo diesel helps delivers up to 11-percent greater highway fuel economy than the outgoing vehicle. Combined with a new 36-gallon (136 L) fuel tank, Duramax-powered Chevrolet Silverado HD pickup trucks can stretch up to 680 miles (1,090 km) of driving range on a single tank of fuel.
The 2011 Duramax will continue to provide outstanding cold-weather performance, with microprocessor-controlled glow plugs capable of gas engine-like start performance in less than three seconds in temperatures as low as -20 degrees F (-29 C), without a block heater.
When it comes to durability and reliability, no other heavy-duty pickup truck manufacturer has the level of experience as Chevrolet, which is why Chevy backs the Duramax with a five-year/100,000-mile powertrain warranty. The engine has been developed to operate for at least 200,000 miles (322,000 km) on a rough-duty cycle without the need for a major overhaul.
“We recognize that a great number of our customers will use the product to its limits, that’s why we design our durability schedules to test for these heavy-towing customers. We also recognize that having any issues when towing large cargo long distances is much more than an inconvenience. That’s why reliability and durability are top focus,” Arvan said.
GM’s 6.6L Duramax diesel features the latest in emission control technology, making it the cleanest Duramax engine ever produced, with NOx emissions reduced by at least 63 percent, compared to the 2010 model. NOx emissions are controlled via a Selective Catalyst Reduction aftertreatment system that uses urea-based Diesel (Emission) Exhaust Fluid (DEF). The DEF is housed in a 5.3-gallon (20 L) tank and needs to be replenished about every 5,000 miles (8,000 km). Electrically heated lines feed the DEF to the emission system to ensure adequate delivery in cold weather.
The 2011 Duramax 6.6L will also include GM’s second-generation diesel particulate filter system. Unlike most of the competition, the Duramax regenerates its diesel particulate filter using a downstream injection of diesel fuel directly into the exhaust stream and can travel up to 700 miles (1,125 km) between regenerations – a 300-mile (482 km) increase over the previous Duramax engine. The use of downstream injection also helps to improve engine life by eliminating concerns surrounding the possibility of diesel fuel contaminating engine oil, which can happen when fuel used for regeneration is introduced directly into the cylinder.
