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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

Frustrated GM investors ask what more Mary Barra can do

DETROIT — General Motors Co Chief Executive Mary Barra has transformed the No. 1 U.S. automaker in her almost five years in charge, but that is still not enough to satisfy investors. Ahead of third-quarter results due on Oct. 31, GM shares are trading about 6 percent below the $33 per share price at which they launched in 2010 in a post-bankruptcy initial public offering. The Detroit carmaker's stock is down 22 percent since Barra took over in January 2014. After hitting an all-time high of $46.48 on Oct. 24, 2017, the shares have declined 33 percent. In the same period, the Standard & Poor's 500 index has climbed 7.8 percent. Several shareholders contacted by Reuters said GM could face a third major action by activist shareholders in less than four years if the share price does not improve. "I've been expecting it," said John Levin, chairman of Levin Capital Strategies. "It just seems a tempting morsel to somebody." Levin's firm owns more than seven million GM shares. Barra has guided the company through the settlement of a federal criminal probe of a mishandled safety recall, sold off money-losing European operations, and returned $25 billion to shareholders through dividends and stock buybacks from 2012 through 2017. GM declined to comment for this story, but the company's executives privately express frustration with the market's reluctance to see it as anything more than a manufacturer tied mainly to auto market sales cycles. GM's profitable North American truck and SUV business and its money-making China operations are valued at just $14 billion, excluding the value of GM's stake in its $14.6 billion Cruise automated vehicle business and its cash reserves from its $44 billion market capitalization. The recent slump in the Chinese market, GM's largest, and plateauing U.S. demand are ratcheting up the pressure. GM is one of the few global automakers without a founding family or a government to serve as a bulwark against corporate raiders. In 2015, a group led by investor Harry Wilson pressed GM to launch a $5 billion share buyback, and commit to what is now an $18 billion ceiling on the level of cash the company would hold. In 2017, GM fended off a call by hedge fund manager David Einhorn to split its common stock shares into two classes. Einhorn, whose firm still owned more than 21 million shares at the end of June, declined to comment about GM's stock price. Other investors said there were no clear alternatives to Barra's approach.

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.