The Redesigned Duramax 6.6L V-8 Turbo – GM's Best Diesel Engine Yet?

2017 Silverado duramax

With the new Duramax engine in the 2017 Silverado HD, pulling trailers is no problem.

This post might read like a bullet list compiled by a Chevy fanboy, but believe us, we're being as neutral as possible when we talk about what's under the hood of the 2017 Silverado HD.

The truth is the new Duramax 6.6L V-8 Turbo could be GM's best diesel engine yet. What makes it better than all the others before it? In short, it's because of more torque, power, and fewer emissions than ever before.

(Almost) Everything New and Improved

17 Duramax engine

The new Duramax 6.6L V-8 Turbo.

It's almost unfair to call the previous generation's Duramax diesel the "old" model since it was already one of the best performing engines in the segment. However, the redesigned Duramax takes some significant leaps over the old one and the other diesels in the market. Here are a few reasons why:

  • Horsepower. The 445 horses in the 2017 Silverado HD are 12% more than the previous year, and 5% more than the next closest competitor in the Ford Super Duty.
  • Torque. The 910 lb-ft of torque from the new Duramax is a 19% increase over a year ago.
  • Smoother, quieter performance. The new turbo-diesel's refinements result in a 38% decrease in engine noise when idling.

Only two things were carried over from the previous Duramax: the bore and the stroke dimensions. Beyond that, essentially all the components are new or have been redesigned.

The new Duramax has a strong and stable cast iron block that houses a larger crankshaft with stronger cast-aluminum pistons and connecting rods. Additionally, the stiffer aluminum heads provide better cooling and incorporate intake and exhaust passages.

The injection system was also the recipient of some much-needed upgrades, which incorporates savvy high-pressure fuel injectors that provide up to seven fuel-delivery events per combustion, making the engine more powerful yet quieter.

But the most important part of the new Duramax is the new electronically-controlled variable-vane turbocharger. Not only does this reduce emissions by 35% but also improves performance for the exhaust brake system.

Chevrolet increased the cylinder head's structure with a honeycomb design, which allows 20% higher pressure. As a result, the crankshaft, connecting rods, piston, and piston pins have all received upgrades to match the higher pressure.

The upgraded engine will get the most from the proven Allison 1000 transmission, which is carried over from the previous generation.

When it comes to diesel engines, exhaust and intake temperatures are important. GM's new intake hood design allows the truck to get cooler air in the engine. Up to 55% of the engine's air comes from the vented hood, which works with the air intake to push air through the filter and into the Duramax's combustion chamber.

The new diesel is also fitted with a Venturi Jet Drain, which ensures the Duramax performs steadily and doesn't get damaged from oil carryover. This separator uses boost from the turbocharger to pump oil back into the sump, which results in maximum performance.

Against the Competition

To say there's a competition between the heavy-duty truck makers of the world is an understatement. Armed with what is essentially a brand new engine, GM wins this round of dynamic diesel performance against Ford and Ram's output figures, hands down.