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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

Two More Recalls Push GM Total To 4.8 Million In A Month

General Motors announced two more recalls late Friday, bringing to 4.8 million the number of cars, trucks and SUVs the automaker has called back for repairs in the past month. The string of recalls, topped by an ignition switch problem in compact cars now linked to 13 crash deaths, has embarrassed the company and sidetracked its new CEO, who started work just over two months ago. GM has admitted knowing about the switch problem a decade ago, yet it didn't recall any cars until February. The recall delay has brought two congressional investigations and probes by the Justice Department and the National Highway Traffic Safety Administration. Late Friday night, GM announced it would recall 490,000 late-model pickup trucks and SUVs because transmission oil cooling lines weren't secured properly in their fittings. Transmission oil can leak from a fitting and hit hot surfaces, causing fires, the company said in a statement. GM said it knows of three fires and no injuries. The recall affects Chevrolet Silverado and GMC Sierra 1500 pickup trucks from the 2014 model year, as well as 2015 Chevrolet Suburban and Tahoe SUVs and the GMC Yukon and Yukon XL SUVs. All have six-speed automatic transmissions. The Silverado is GM's top-selling vehicle and an important profit center for the company. The GMC Sierra also is among GM's top sellers. Dealers will inspect the transmission oil cooling line fittings and make sure they're securely seated, at no cost to owners. Also Friday night, GM announced the recall of 172,000 Chevrolet Cruze compact cars because the right front axle shaft can fracture and separate while being driven. The recall affects cars from the 2013 and 2014 model years equipped with 1.4-liter turbocharged four-cylinder gasoline engines. If a shaft fractures, the wheels would lose power without warning and the cars would coast to a stop. GM says it has warranty reports of several dozen shaft fractures. It is not aware of any crashes or injuries. Dealers will replace the shafts free of charge. The recall allows dealers to resume selling affected Cruzes. GM issued a stop sale order on the cars Thursday night. The recall also covers about 2,500 replacement shafts used to fix manual transmission Cruzes that were recalled last September. In all, GM has recalled 4.8 million vehicles since last month, two million more than the company sold last year in the U.S.

GM issues stop-sale for 3 SUVs over incorrect MPG rating

This week, GM sent a memo to Chevy, GMC, and Buick dealers to tell them to stop selling three SUVS. The 2016 Chevy Traverse, the GMC Acadia, and the Buick Enclave all have EPA window stickers that show higher fuel economy ratings than the vehicles actually have. Unlike other recent – and very public – fuel economy ratings problems from VW and Mitsubishi, it doesn't seem like GM did anything wrong with the testing for these vehicles, it just misprinted the labels. New labels are being printed and should arrive at dealerships this weekend and early next week. After that, the SUVs will be able to be sold and delivered again. The official fuel economy rating for the three SUVs are all the same. The correct numbers for the all-wheel drive versions are 17 miles per gallon combined, 15 city, and 22 highway. The stickers say the SUVs get 17/24/19. The front-wheel driver models were also incorrectly labeled, and the total number of affected vehicles is 59,823. In the memo, GM said the problem was caused by an "inadvertent error," Automotive News says. GM is working with the EPA to solve the issue. We have asked GM for a comment on the mistake and will update this post if we hear back. Related Gallery 2013 GMC Acadia View 16 Photos News Source: Automotive News – sub. req. Government/Legal Green Buick Chevrolet GM GMC Fuel Efficiency mpg gmc acadia chevy traverse