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GM Recalling Another 2.7 Million Vehicles In Five Separate Campaigns

The recalls keep rolling in from General Motors, evidently keen to avoid repeating the mistakes of the ignition-switch debacle and clean house. This time they're all coming at once, with five separate recalls announced together covering approximately 2.7 million vehicles. The largest of the five actions involves over 2.4 million units of the previous-generation Chevrolet Malibu and Malibu Maxx, Pontiac G6 and Saturn Aura in order to fix brake light wiring harness, which have been found to be susceptible to corrosion. The recall is separate from the 56k Aura sedans which GM recently recalled over faulty shift cables, not to mention the previous massive recall of 1.3 million vehicles – some of them the same models – but appears to have resulted from the National Highway Traffic Safety Administration investigation that started with the G6 almost a year ago. The second-largest campaign involves the 2014 Chevy Malibu, specifically those fitted with GM's 2.5-liter engine and stop/start system, approximately 140,000 examples of which has been found to have problematic brakes. The issue does not appear to be connected to the recall of 8k Malibu and Buick LaCrosse sedans (also involving brake woes) which we reported upon last week. Four crashes have been reported in such models, but GM admits it's not yet clear if the problem was a contributing factor in the accidents. A further 112k Corvette models from the 2005-2007 model years are being called in for problems with their low-beam headlamps resulting from a flexing relay control circuit wire that's not meant to bend. GM says it is "aware of several hundred complaints" about this issue, but notes that there have been no reports of related accidents. In addition, over 19k examples of Cadillac CTS from the 2013 and 2014 model years are being recalled over windshield wipers that might not work after a jump start. Finally, GM is also bringing in 477 examples of its 2014 Chevy Silverado, Tahoe and GMC Sierra (though not the Yukon) to fix a problem with a tie rod in its steering rack. As ever, all recall repairs will be performed free of charge, and GM is now estimating that recall-related actions this quarter will result in an estimated $200-million charge against its second-quarter earnings. Read the full announcement from GM below for further details.

GM patent reveals new two-stage turbocharger

Modern turbochargers may be some of the best ever made, but performance is something that engineers are always trying to improve. According to GM Inside News, General Motors (GM) is hoping to alleviate some of the negative aspects of a two-stage turbocharger setup with a newly-patented design. The patent, that was filed on May 19, 2016, reveals a clever bypass system that allows the engine, a four-cylinder unit, to optimize both the low-pressure and high-pressure inlets for its respective functions. According to the filing, a conventional two-stage turbocharger setup is engineered to allow both turbines to operate simultaneously at low and mid engine speeds. At high engine speeds, only the low-pressure turbine works. The setup can't isolate either the low or high pressure side, which can impair low-end performance. GM's new two-stage turbocharger setup looks to eliminate this by linking the high-pressure turbo to the exhaust manifold through the high-pressure inlet duct. The low-pressure turbo is attached to the high-pressure turbo by a low-pressure inlet duct, which is linked to a connecting channel. A single actuator that is housed in the exhaust manifold creates a bypass that can opens the high-pressure inlet or close the connecting channel. Depending on what the engine load and speed is, the ECU guides the actuator—a single rotating spindle with discs corresponding to flanges on the high and low pressure sides—to isolate one of the two turbos. Isolating the turbos allow the respective inlets to be engineered for the best possible fluid dynamic performance. The setup should increase performance and decrease lag. There's no word on what car this setup will make an appearance on, but it will most likely be used in premium vehicles before trickling down to the rest of GM's vehicles. Related Video: News Source: GM Inside News, AutoGuide via GM Authority Cadillac Chevrolet GM Technology Sedan turbo patent engine turbocharging

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.