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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.

GMC Envoy could be returning as GM files for 'Envoy' trademark

The GMC Envoy could be on its way back, if a recent GM trademark filing is any indication of the future. To be exact, GM's trademark filing is for the name "Envoy," and is applicable to "motor vehicles, namely, sport utility vehicles, engines therefor and structural parts thereof." A victim of the recession and high gas prices, the original Envoy – related to the Blazer, and more recently the TrailBlazer and similar GM SUVs – was discontinued after the 2009 model year. In today's SUV-happy market of low gas prices, unearthing the somewhat familiar Envoy name makes a certain amount of sense. As soon as gas prices start trending in the other direction, we'll all be saying the opposite, though. What this SUV will take shape as is the big question now. With the Chevrolet Blazer well and truly on its way, there's every reason for a GMC version of Chevy's stylish new crossover sporting the Envoy name. Another, less likely, possibility is a Traverse-sized vehicle to slot between the shorter Acadia (10 inches shorter than the Chevy Traverse) and the body-on-frame Yukon. GM could come out of left field and make the Envoy a Buick too. It fits the bill with the "En" beginning, and Buick undoubtedly has crossovers in the works. We think that's even more unlikely, but it's important to remember that we're still in the speculation phase. Soon we'll drive Chevy's new Blazer, and perhaps have more news then. Check in next week for that. Related video:

GM recalling Silverado and Sierra HD diesel pickups over fuel gauge follies

General Motors is recalling 9,733 of its heavy-duty twins over concerns with their 6.6-liter diesel engines and dual fuel tanks. The recall covers some Chevrolet Silverado HD and GMC Sierra HD pickups from model years 2012 and 2013, although the exact dates that the recalled trucks were built isn't specified. There's also no mention of how many models come from Chevrolet and how many are from GMC.
The problem rests with the transfer pump responsible for moving fuel from the rear tank to the front tank - it could fail, resulting in an inaccurate fuel gauge. It hardly requires explaining, but a faulty fuel gauge could leave drivers in a situation where they run out of diesel.
GM will begin notifying customers of affected vehicles, who will be asked to report to their dealers for a free replacement transfer pump.