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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 recalls 3,300 pickups and SUVs for new ignition-switch issue [UPDATE]

UPDATE: A statement from GM about the recall has been added below. The exact total of vehicles affected is 3,296, including 3,073 of them in the US. General Motors isn't letting an ignition-switch problem grow into a massive scandal again. The automaker is recalling about 3,300 North American trucks and SUVs. They are: the 2014 Chevrolet Silverado and GMC Sierra and the 2015 Chevy Suburban and Chevy Tahoe, as well as 2015 model heavy-duty pickups, the Detroit News reports, citing an Associated Press story. The issue appears to have been caught fairly quickly. In this case, the keys can get stuck in the "start" position and then slip to "accessory" if bumped. This is because the ignition lock gears have an outer diameter that's larger than the specifications allow. When that happens the engine shuts off, and the driver loses assistance to the steering and brakes. The airbags might also be affected. The vehicles get a new ignition-lock housing to fix the problem. According to the Detroit News, an employee who experienced the problem with the switch discovered the issue, and this person then let officials at the automaker know as part of the Speak Up for Safety program. A total of five reports of the fault were discovered. However, there are no cases of injuries or crashes. The claims to the automaker's resolution program eventually tallied that GM's previous ignition switch problem included 124 deaths and 275 injuries. The company also had to recall millions of vehicles and pay significant fines to the US government. GM Statement General Motors is recalling 3,073 full-size trucks from the 2014 and 2015 model years in the U.S. Some of these vehicles may have an ignition lock actuator gear with an outer diameter that exceeds specifications, which may make turning the ignition key difficult. The ignition key could get stuck in the "start" position. This may be more likely at higher interior ambient temperatures. If the vehicle is driven with the key stuck in the "start" position, and the vehicle experiences a significant jarring event or the vehicle's interior temperature cools, the ignition lock cylinder could move out of the "start" position, rotate past the "run" position, and move into the "accessory" position, leading to loss of power steering assist, power brakes and potentially air bag deployment in certain crashes. Dealers will replace the ignition lock housing.

GMC introduces off-road performance package for Sierra AT4

GMC is giving its off-road-focused Sierra AT4 pickup even more performance with some factory-installed upgrades. The package is called the AT4 Off-Road Performance Package. With it you'll get the 6.2-liter V8 engine upgrade, cat-back performance exhaust system, performance air intake and 18-inch aluminum wheels shod in Goodyear Wrangler DuraTrac tires. The upgraded performance comes in the form of extra power. Thanks to the bolt-ons, you gain 15 horsepower and 9 pound-feet of torque over the 6.2-liter in stock form. This increases output to 435 horsepower and 469 pound-feet of torque — not too shabby. This package is priced at $4,940, and available for order now. That's a hefty price for what amounts to some minimal bolt-on modifications you could easily do yourself. However, buying it through GM means you get to keep your warranty in place. The Sierra AT4 already has more off-road features than a normal Sierra 1500. You're getting a two-inch lift, four-wheel drive with two-speed transfer case, locking rear differentials, skid plates, Rancho off-road shocks and hill descent control. Both the wheels and tires are available as options already, but this package just bunches related stuff together. It'll be up to you to decide if an exhaust and intake are worth the extra dough. Related video: This content is hosted by a third party. To view it, please update your privacy preferences. Manage Settings.