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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.

GM phasing out light-duty 1500-series vans

In the market for a fullsize van but don't need a heavy-duty model? You're in the minority, and you're also out of luck. That's because there are barely any more fullsize vans on the market with gross vehicle weight rating of less than 8,500 pounds, the threshold that separates light- and heavy-duty vans.
According to PickupTrucks.com, neither the Ford E-Series, Ram ProMaster, nor Mercedes-Benz Sprinter are available in light-duty versions. Few of the Ford Transit configurations are, either, and now General Motors is discontinuing production of the 1500-series Chevy Express and GMC Savana.
Apparently light-duty versions accounted for just 23 percent of Express sales and only 7 percent of Savanas. Add to that the fact that these 1500 versions were the only ones using the old generation of engines and suspension, and that the Wentzville plant near St. Louis, Missouri, is trying to make room for the next Chevy Colorado and GMC Canyon pickups, and the fate of the light-duty GM van was sealed.

GM's MPG overstatement could affect 2 million vehicles

Late last week, GM admitted that three of its large SUVs fuel economy window stickers did not match their actual efficiency ratings, and so the vehicles couldn't be sold. The stickers on the 2016 Chevy Traverse, GMC Acadia, and Buick Enclave said their ratings were one to two miles per gallon better than they should have been. Officially, the number of affected vehicles sits at about 60,000. But Consumer Reports makes a good point: what's up with all of the previous model year SUVs that are basically the same vehicle? To wit: the 2016 model year vehicles are not substantially different than the 2015 or the 2014, or even going all the way back to 2007. On the EPA's fuel economy website, all of these older models will "have better stated fuel economy numbers than the new vehicles in GM's dealerships," Consumer Reports noted. CR's best point, and the one that makes the 60,000 number potentially grow to 2 million if all of the vehicles built on this platform are affected, is that "[i]t seems unlikely that the company would change the powertrain on these carryover models so late in their model cycles in a way that would cause a dramatic, negative impact on fuel economy." GM says that earlier model year SUVs are not affected and the EPA did not respond to CR's question about the potential for more discrepancies. We've seen automakers reverse course before, so if GM has to come out with a mea culpa soon, don't be surprised. GM is rushing corrected stickers to dealers so that the SUVs can be sold again, but a fix for the already-sold vehicles could be trickier to solve. Related Video: Related Gallery 2013 GMC Acadia View 16 Photos News Source: Consumer Reports Government/Legal Green Buick Chevrolet GMC Fuel Efficiency mpg gmc acadia chevy traverse