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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

Cadillac XT5 platform to underpin three-row crossover

Cadillac just launched the XT5 crossover to replace the SRX. But that's only the start. Speaking with Automotive News, Caddy president Johan de Nysschen confirmed that a new three-row crossover is also on the way. The seven-seater is based on a stretched version of the flexible platform underpinning the XT5, which we just drove recently. Taking that approach will give the luxury brand a larger crossover to pit against the likes of the Infiniti QX60, Audi Q7, and Volvo XC90 without having to develop one from scratch. It will also give buyers a more car-like alternative to the larger, truck-based Escalade. "It's one of the benefits of having this very flexible architecture. We can expand it, make it longer and wider. That gives us the ability to develop the car very quickly, as opposed to starting from scratch," de Nysschen told AN. "It's not running yet. It is a program request that we initiated with the engineers only last year. They are working at remarkable, record-breaking speed to get us the car." The new model would likely be called the XT7 and offer similar levels of equipment to the existing, smaller XT5. The existing mid-size model packs a 3.6-liter V6 mated to an eight-speed automatic transmission and comes in four trim levels. Related Video:

GM extending warranties on Cadillac CTS-V and Chevy Camaro ZL1 for supercharger issue

Okay General Motors, we've sat by and watched you recall the compact cars, crossovers and pickup trucks, and aside from reporting on it, we've been fairly quiet. This, though, this will not do. We can almost tolerate the recalls on the bread-and-butter cars, but leave the performance vehicles alone.
According to a report from The Car Connection, GM has discovered a problem with the superchargers of the 6.2-liter V8s found in the Chevrolet Camaro ZL1 and the Cadillac CTS-V. Apparently, the issue rests around the internal bearing shaft grease, which can become contaminated (we aren't sure with what). If left unchecked, it'll first lead to a rattle at idle, which goes away under slight throttle. The real warning stage is when a high-pitched squeal develops, signaling that the bearing shaft has failed. Naturally, severe engine damage is the next step (although it's possible that the engine will also just refuse to turnover, although neither case is desirable).
According to TCC, GM will replace the superchargers on vehicles that have exhibited symptoms of bearing shaft failure free of charge. It will also, allegedly, be extending the warranty on all supercharged ZL1s and CTS-Vs to 10 years or 120,000 miles (whichever comes first), from the date of purchase. Officially, only 2009 to 2013 CTS-Vs and 2012 to 2013 ZL1s are suffering from this issue.