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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

Fullsize GM SUVs have a problem that's making owners sick

Some fullsize SUV owners are getting sick, thanks to a buffeting and vibration problem in 2015 model year examples of the Chevy Tahoe and Suburban, Cadillac Escalade, and GMC Yukon. According to owners' complaints to the National Highway Traffic Safety Administration, the issue can vary from an annoying vibration inside the cabin to an experience so severe that it leads to dizziness and headaches. General Motors is aware of the complaints, but the fix isn't so simple. According to spokesperson Tom Wilkinson to Autoblog, the company "has been tracking this issue for a while." The problem has a fairly low incidence rate, but when it does occur the issue can be "uncomfortable and annoying for owners." There's no precise cause for the issue, Wilkinson claims, and in some cases, simply balancing the tires or changing the door seals can make it go away. However, not all of the fixes are so simple. AutoGuide dug deep into the problem and discovered a GM preliminary information bulletin that advised dealers to remove the headliner and to check the roof's bonds to the bows that go across the vehicle. However, that document included a note that the solution might not entirely eliminate things. According to AutoGuide, adding Dynamat insulation to the roof sometimes helped the problem. A GM spokesperson also told AutoGuide the company fixed the problem at the end of the 2015 model year, and didn't go into any more detail. This roof issue seems linked to some of the worst droning in these SUVs. According to one complaint from a 2015 Suburban owner to NHTSA: "Roof will not remain attached to the roof bows. This causes the buffeting similar to a window being down when all are up. The results span from annoying to painful." A 2015 Yukon owner claims to have another alleged cause for the problem in a NHTSA complaint from February 2015. This person brought their SUV to the dealer seven times over the course of four weeks for vibrations. The dealer replaced the driveshaft, suspension components, and more, but nothing worked. According to an engineer to the service adviser: "In an effort to prevent roll overs, they designed the frame and body mounts too stiff. There are 40 engineers working on issues, they have no solutions that work across the board." Wilkinson told Autoblog that GM is working with customers on an individual basis to rectify things. Since these are newer vehicles, dealers should also fix the problem under warranty.

GM tells owners not to use SUV wipers due to fire risk

General Motors is recalling 31,685 examples of the 2016 Buick Enclave, Chevrolet Traverse, and GMC Acadia because a short circuit in the windshield wiper motor can potentially lead to a fire. Due to the danger, the company is asking owners not to use the wipers until the problem is fixed, according to The Detroit Free Press citing the Associated Press. A manufacturing defect in the wiper motor cover means that the electrical terminals can come into contact and cause a short. The part could "melt, smoke, or catch fire," according to a statement from GM. The company will get them fixed immediately, and dealers will replace the cover. If there's bad weather at the time the owner specifies to get the recall work completed, the automaker will come pick up the crossovers. Depending on parts availability, the automaker will supply a rental car for customers, as well. The issue was discovered at the factory. According to the company's statement, only 6,405 actually made it to customers, and they were notified immediately by overnight letter. The rest were in dealer stock. The affected crossovers carry build dates between August 18, 2015 and September 24, 2015. Of those, there are 29,295 in the US and 1,073 in Canada. GM Statement: General Motors has told the National Highway Traffic Safety Administration that it will recall approximately 29,295 2016 model year Chevrolet Traverse, Buick Enclave and GMC Acadia SUVs in the U.S. because the front windshield wiper motor may overheat when in use because of a manufacturing defect. In some cases, the front windshield wiper motor cover may melt, smoke or catch fire. The approximately 6,405 customers who have taken delivery of these vehicles were notified by overnight letter and are urged to contact a GM dealer as soon as possible to arrange a service appointment. These customers should not use the front windshield wipers until they have been repaired. If weather conditions prevent driving the vehicle without using the windshield wipers, GM will arrange to pick up the vehicle for servicing. If repair parts are unavailable, GM will provide a rental car at no cost until parts become available. The total population, including Canada, Mexico and exports, is approximately 31,685. About 25,280 of these vehicles are in dealer stock and will not be sold until repairs are made.