2008 Gmc Sierra 2500 Sle2 Leather Diesel 4x4 Sb Duramax Allison 08 on 2040-cars

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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.

5 things we love about the 2019 GMC Sierra AT4

NEW YORK — The 2019 GMC Sierra AT4 proves that GM's upmarket truck and SUV brand is getting serious about offering rough-and-tumble capability to rival the Ford F-150, Toyota Tundra, Ram 1500 and Nissan Titan. Until the Sierra AT4 rolled onstage at a media event in lower Manhattan, prior to this year's New York Auto Show, the GMC brand had been more focused on luxury touches like fancy chrome wheels and posh interiors — no surprise, considering the upscale SLT and Denali trim levels account for the vast majority of GMC sales. So now GMC wants to get muddy and adventurous? Well, yes and no. The AT4 adds hardware that'll take truck buyers off the beaten path, though this GMC isn't anywhere close to being a Spartan, no-frills work truck. To better explain, let's look at five key features we love about the 2019 GMC Sierra AT4: More than stickers and chrome The Sierra AT4 isn't a cynical marketing ploy, there is some true all-terrain toughness built into this pickup truck. A factory-installed lift kit raises the AT4 by two inches, while Rancho monotube shocks, a locking rear differential, a two-speed transfer case and standard all-wheel drive prove this GMC can dare to venture off paved surfaces — though you might risk getting mud and muck on the truck's handsome 18- or 20-inch alloy wheels. Power and economy The Sierra AT4 comes standard with a 5.3-liter V8 coupled to an eight-speed automatic transmission. In the standard Sierra 1500, this engine produces 355 horsepower. GMC didn't mention engine specs here in New York, though it's possible the AT4 might get a small power bump. This engine should be plenty for most truck buyers, though GMC offers two tempting alternatives. These include a turbo-diesel 3.0-liter inline-six, along with a 6.2-liter V8. Both motors are paired to stop-start fuel-saving systems, along with a new 10-speed automatic transmission. Carbon fiber cool factor The GMC Sierra's available carbon-fiber cargo bed, called CarbonPro in GMC-speak, trims 62 pounds of weight, as compared to a traditional all-steel bed. This slick feature uses carbon composites for interior panels and, judging from GMC's videos of burly bricks and huge hammers being thrown into a CarbonPro cargo bed, it should prove more than up to the task of ... well, having someone throw bricks and hammers into the cargo area.

GM diesel pickups first to undergo extra EPA, CARB testing

The effects of Volkswagen's long-running diesel emissions evasion are starting to spill over to other automakers, but General Motors is taking things in stride. The 2.8-liter, four-cylinder Duramax in the 2016 Chevrolet Colorado and GMC Canyon is the first engine to get extra scrutiny by the Environmental Protection Agency and the California Air Resources Board, Automotive News reports. Rather than just the usual in-lab test, it's also being checked on the road. However, the extra evaluation shouldn't have any impact on when the trucks with his mill hit dealers later this fall. "We're in our final stages of the EPA certification, and our launch is on track," Chevy spokesperson Otie McKinley tells Autoblog. The four-cylinder diesel in the trucks makes 181 horsepower and 369 pound-feet of torque, and the automaker is touting low NOx production. In the announcement for the Colorado's specs, the company calls it "the cleanest diesel truck engine ever produced by General Motors." The tech includes exhaust gas recirculation to lower combustion temperatures and improve emissions. There's also a urea tank like on the bigger diesels for full-size trucks, and it gets refilled in time with oil changes. An indication on the instrument panel lets drivers know when that's needed, too. Even with the more demanding testing, the company doesn't seem too worried about the four-cylinder passing. "Part of our development process is on-road and off-road [laboratory] testing," Scott Yackley, Chevy Trucks assistant chief engineer, said to Automotive News. In the wake of the VW scandal, the EPA has pledged more rigorous testing. Before, on-road emissions evaluations were largely limited to heavy-duty vehicles, but the agency has decided to apply the checks more often to other models. There's also now greater cooperation with Canadian authorities.