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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 pauses 3.0-liter turbodiesel production due to a supplier shortage

General Motors confirmed it has temporarily stopped taking orders for trucks and SUVs equipped with the 3.0-liter Duramax turbodiesel six-cylinder engine. It blamed the last-minute pause on a supplier-related shortage. Website TFL Truck first reported the news, and a representative from General Motors quickly confirmed it. The spokesperson explained the issue is due to a "temporary part shortage" and added that production will resume "as soon as possible," meaning the Duramax engine (which is called LM2 internally) is not going away permanently. Additional details are not available, so we don't know if the issue is related to the ongoing chip shortage. Rather than delay deliveries and create a backlog, General Motors is reportedly asking its dealers to encourage buyers who want a turbodiesel engine to instead select either the 5.3-liter V8 or the 6.2-liter V8, depending on the model selected. Both are gasoline-powered units. There's no word yet on when Duramax production will resume. The shortage affects several models, including Chevrolet's Tahoe, Suburban, and Silverado 1500 and GMC's variants of these trucks. Cadillac's Escalade is temporarily diesel-less as well. Heavy Duty variants of the Silverado and the Sierra are not affected because they're powered by a different Duramax engine with eight cylinders. Motorists seeking a full-size SUV powered by an efficient turbodiesel engine are temporarily out of options because the Tahoe/Yukon and the Suburban/Yukon XL had the segment to themselves. The Duramax was surprisingly popular, too: in May 2021, GM Authority reported that the turbodiesel straight-six represented 8% of Suburban sales and 6% of Tahoe sales. Installed in a rear-wheel-drive Tahoe, the engine returns 21 mpg in the city, 28 mpg on the highway, and 24 mpg in a combined cycle, figures that make the body-on-frame behemoth more efficient than the unibody, front-wheel-drive Chevrolet Blazer that's 20 inches shorter and approximately 1,700 pounds lighter. Related video: 2021 Chevrolet Tahoe 3.0L Duramax engine

Cadillac ATS Coupe headed for Detroit reveal

Cadillac wouldn't be Cadillac without its two-door models. But the XLR has been discontinued for over four years now, the Elmiraj concept may never see production and the future of the CTS Coupe is still up in the air. That leaves just the ELR, which may not be conventional enough for traditional Cadillac coupe buyers. Fortunately a new coupe is coming along to fill the void.
According to Edmunds, Cadillac will reveal the new ATS coupe just a couple of months from now at the Detroit Auto Show. Expected to mechanically mirror the existing ATS sedan, the new coupe will also more conventionally resemble its four-door counterpart than the CTS, whose coupe version was distinguished by a rakishly sloping roofline.
Expect the same choice of engines to carry over, with a 2.5-liter four serving as the base engine, and both a 2.0-liter turbo four and a 3.6-liter V6 offering more power for those looking for that extra bit of oomph. Following the Detroit reveal, sources anticipate the ATS coupe to go on sale next summer.