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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

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

GM recalling 426,000 sedans over faulty transmission shift cable

General Motors is recalling some 426,240 sedans that may have a faulty transmission shift cable, according to a National Highway Traffic Safety Administration report this morning. The recall concerns a fault within four-speed automatic transmissions equipped on 2007-2010 Saturn Aura models, and 2008-2010 Chevrolet Malibu and Pontiac G6 models.
The report specifies that tabs on the transmission shift cable may fracture and separate. Such a fault could cause a discrepancy between the actual position of the transmission and the apparent position of the shift lever.
GM is currently working to notify owners of the vehicles in question, and dealers will check and replace shift cables free of charge. Scroll down to read the complete NHTSA report.