Chevrolet announced the redesigned Duramax 6.6L V-8 turbo-diesel offered on the 2017 Silverado HD. This next-generation redesign offers more horsepower and torque than ever — an SAE-certified 445 horsepower (332 kW) and 910 lb.-ft. (1,234 Nm) — to enable easier, more confident hauling and trailering.
Along with a 19 percent increase in max torque over the current Duramax 6.6L, the redesigned turbo-diesel’s performance is quieter and smoother, for greater refinement. In fact, engine noise at idle is reduced 38 percent.
“With nearly 2 million sold over the past 15 years, customers have forged a bond with the Duramax diesel based on trust and capability,” said Dan Nicholson, vice president, Global Propulsion Systems. “The new Duramax takes those traits to higher levels.”
The new Duramax 6.6L shares essentially only the bore and stroke dimensions of the current engine and incorporates a new, GM-developed control system. The Duramax’s signature low-rpm torque production hasn’t changed and still offers 90 percent of peak torque at a low 1,550 rpm and sustains it through 2,850 rpm.
“Nearly everything about the Duramax is new, designed to produce more torque at lower rpm and more confidence when trailering or hauling,” said Gary Arvan, chief engineer. “You’ll also notice the refinement improvements the moment you start the engine, and appreciate them as you cruise quietly down the highway — with or without a trailer.”
Additional highlights include:
- New, stronger cylinder block and cylinder heads
- New, stronger rotating and reciprocating assembly
- Increased oil- and coolant-flow capacity
- New EGR system with single cooler and integrated bypass
- New electrically actuated/electronically controlled turbocharging system
- All-new advanced solenoid fuel system
- All-new electronic controls
- New full-length damped steel oil pan that contributes to quietness
- New rocker cover/fuel system acoustical treatments
- B20 bio-diesel compatibility
- SAE-certified 445 net horsepower (332 kW) at 2,800 rpm
- SAE-certified 910 net lb.-ft. of torque (1,234 Nm) at 1,600 rpm
A new, patent-pending vehicle air intake system — distinguished on the Silverado HD by a bold hood scoop — drives cool, dry air into the engine for sustained performance and cooler engine temperatures during difficult conditions, such as trailering on steep grades. Cooler air helps the engine run better under load, especially in conditions where engine and transmission temperatures can rise quickly. That allows the Duramax to maintain more power and vehicle speed when trailering in the toughest conditions.
The intake design is another example of the advanced integration included in the 2017 Silverado HD that makes it over-the-road capable.
As with previous versions, the new Duramax block features a strong cast-iron foundation known for its durability, with induction-hardened cylinder walls and five nodular iron main bearings. It retains the same 4.05-inch (103mm) and 3.89-inch (99mm) bore and stroke dimensions as the current engine, retaining the Duramax’s familiar 6.6L (403 cu.-in./6,599 cc) displacement.
A deep-skirt design and four-bolt, cross-bolted main caps help ensure the block’s strength and enable more accurate location of the rotating assembly. A die-cast aluminum lower crankcase also strengthens the engine block and serves as the lower engine cover, while reducing its overall weight.
The new engine block incorporates larger-diameter crankshaft connecting rod journals than the current engine, enabling the placement of a stronger crankshaft and increased bearing area to handle higher cylinder loads.
An enhanced oiling circuit, with higher flow capacity and a dedicated feed for the turbocharger, provides increased pressure at the turbo and faster oil delivery. Larger piston-cooling oil jets at the bottom of the cylinder bores spray up to twice the amount of engine oil into oil galleries under the crown of the pistons, contributing to lower engine temperature and greater durability.
A new, two-piece oil pan contributes to the new Duramax’s quieter operation. It consists of a laminated steel oil pan with an upper aluminum section. The aluminum section provides strength-enhancing rigidity for the engine, but a pan made entirely of aluminum would radiate more noise, so the laminated steel lower section is added to dampen noise and vibration.
There’s also an integrated oil cooler with 50 percent greater capacity than the current engine’s, ensuring more consistent temperatures at higher engine loads.