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Chevy's 6.6-liter Duramax is pretty much all new

To say there's a heated battle in heavy-duty pickups is an understatement, with Chevrolet, Ford, and Ram constantly trading blows of increased torque, horsepower, and towing capacity. The latest salvo is the revised, more powerful turbo diesel 6.6-liter Duramax V8 in the 2017 Chevy Silverado. It has 910 pound-feet of torque, an increase of 145, putting it nearly level with the Ford Super Duty. Here's a closer look at where those gains come from. How exactly did Chevrolet add all that torque plus 48 horsepower? The automaker essentially took a fine-tooth comb to the entire engine. Chevy says it changed 90 percent of the V8, and the cumulative effect of those small changes adds up to big increases. As you might guess, the turbocharger is updated. The larger unit features electric actuation of the variable nozzle turbine (VNT), and what Chevy calls a double axle cartridge mechanism that separates the VNT moving parts from the housing. That helps with heat performance as well, with a claim that the exhaust side of the turbo can run continuously up to 1,436 degrees Fahrenheit. Helping that cause are six exhaust gaskets made of Inconel - an nickel alloy that contains chromium and iron – and upgraded stainless steel for the exhaust manifold. Despite having the same cast iron cylinder block, albeit with some minor enhancements, the engine has new cylinder heads, pistons, piston pins, connecting rods, and crankshaft, which have all been upgraded to handle 20 percent higher cylinder pressures. Alongside the increase in pressure, Chevrolet also increased the cylinder head's structure with a honeycomb design. The pattern features high-strength aluminum with dual layer water jackets that not only improve strength, but also optimize water flow for better cooling. For 2017, the cylinder head also benefits from integrated plenum that aids the engine in getting more air under heavy loads. The cylinder head isn't the only component to get a minor update, as the pistons have a larger diameter pin for improved oil flow. The same detailed improvements has been bestowed to the humble connecting rods (second in our hearts only to the inanimate carbon rod). The new design has the bolts oriented roughly 45-degrees to the rod instead of parallel. The angle split design, as it's called allows for easier passage through the cylinder.

Leak reveals GM's 2017 heavy duty diesel trucks to get 910 lb-ft of torque [UPDATE]

UPDATE: Chevrolet officially announced specs for the 2017 Silverado HD and the rumors were true. The truck's new Duramax 6.6-liter turbo-diesel V8 puts out 445 horsepower and 910 pound-feet of torque. Chevrolet says the new motor produces 19 percent more torque and 12 percent more horsepower, while producing 35 percent fewer emissions. Overall, the new engine is a big improvement over the current motor, which generates 397 horsepower and 765 pound-feet of torque. According to Truck Trend, GM's newest heavy duty pickup trucks will pick up quite a bit more power and torque. The publication spotted a recent GM Powertrain ordering catalog that had the engine specs for the 2017 model year and managed to get some screenshots before the catalog was taken down, and they can be viewed here. The screenshots revealed that the 6.6-liter turbodiesel V8 powering the Silverado and Sierra heavy duty models will boast 445 horsepower and 910 lb-ft of torque. This is a substantial gain over the current models' 397 horsepower and 765 lb-ft of torque, and as Truck Trend points out, it exceeds the Ford Super Duty line's horsepower output of 440, but comes short of the 925 lb-ft rating. Truck Trend credits part of this output gain to the new intake system GM will introduce on the 2017 heavy duties. The intake gets 60 percent of its air from a scoop on the hood, with the other 40 percent coming from behind one of the front fenders. GM doesn't reveal horsepower figures in the press release about the scoop, but it does say the cooler air helps with maintaining the engine's output, and that the scoop does produce a ram-air affect, providing more air at speed. As we know, more air plus more fuel equals more power, but there's likely more to the power increase in this engine than only the intake. Related Video: News Source: Truck Trend via MSN Chevrolet GM GMC Truck Diesel Vehicles

Should heavy-duty pickup trucks have window stickers with fuel mileage estimates?

If you were to stroll into your nearest Chevrolet, Ford, GMC, Nissan, or Ram dealership, you'd find a bunch of pickup trucks. Most of those would have proper window stickers labeled with things like base prices, options prices, location of manufacture, and, crucially, fuel economy estimates. But you'd also run across a number of heavy-duty trucks with no such fuel mileage data from the Environmental Protection Agency. The EPA doesn't require automakers to publish the valuable miles-per-gallon measurement for vehicles with gross weight ratings that exceed 8,500 pounds. That makes it difficult for consumers to compare behemoths powered by turbocharged diesel engines – between one another, and between smaller, gasoline-fueled trucks. Consumer Reports doesn't think it should be this way, and it's spearheading an effort (PDF link) to get the government to require manufacturers to publish fuel economy estimates. In its own testing, CR found that heavy-duty pickups powered by Ford's Power Stroke, GM's Duramax, and FCA's Cummins diesel engines (which doesn't include the Ram's EcoDiesel) get worse fuel mileage than their lighter-duty gas-powered siblings. We're not so sure HD-truck buyers are unaware of this fact – big diesels don't really come into their own until big loads are placed in their beds or attached to their trailer hitches. Under heavy workloads, the diesel trucks will almost certainly return greater efficiency than a similar gas-powered truck. What's more, HD trucks with lumbering diesels in general make the driver feel more confident while towing due to greater torque at low engine RPM than gas trucks. They also offer greater max-weight limits. Still, we agree EPA fuel mileage estimates should be offered for heavy-duty pickups. And we think the comparisons provided by Consumer Reports might be interesting to potential buyers. Click here to see the results of CR's tests, and let us know what you think using the poll below. Related Video: Featured Gallery 2017 Ford F-Series Super Duty: First Drive View 22 Photos News Source: Consumer Reports Government/Legal Green Read This Chevrolet Ford GMC Nissan RAM Fuel Efficiency Truck Commercial Vehicles Diesel Vehicles poll gmc sierra hd chevy silverado hd