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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

40+ cars that barely avoid the gas guzzler tax

The Gas Guzzler schedule, with mpg ratings and charges that haven't changed since 1991, lays out which fuel-swillers owe what to Uncle Sam.
I started thinking about the "Gas Guzzler Tax" - considerably less well known as The Energy Tax Act of 1978 - when I was driving Dodge's new Challenger SRT Hellcat last week. Unsurprisingly for a car that can burn 1.5 gallons of gas per minute at max tilt, theoretically able to empty a full tank of premium in about 13 minutes, the Hellcat will be subject to the Gas Guzzler Tax schedule when it goes on sale.

Best and Worst GM Cars

Oh yes, because we just love receiving angry letters from devoted Pontiac Grand Am enthusiasts, we have decided to go there. Based on a heated group Slack conversation, the topic came up about the best and worst GM cars. First of all time, and then those currently on sale, and then just mostly a rambling discussion of Oldsmobiles our parents and grandparents owned (or engineered). Eventually, three of us made the video above. Like it? Maybe we can make more. Many awesome GM cars are definitely going unmentioned here, so please let us know your bests and worsts in the comments below. Mostly, it's important to note that this post largely exists as a vehicle for delivering the above video that dives far deeper into GM's greatest hits and biggest flops, specifically those from the 1980s and 1990s. What you'll find below is a collection of our editors identifying a best current and best-of-all-time choice, plus a worst current and worst-of-all-time choice. Comprehensive it is not, but again, comments. -Senior Editor James Riswick Best Current GM Vehicle Chevrolet Corvette We were flying by the seats of our pants a bit in this first outing and my notes were similarly extemporaneous. When it came time to tie it all together on camera, I failed spectacularly. Thank the maker for text, because this gives me the opportunity to perhaps slightly better explain my convoluted reasoning. I chose the C8 Corvette because it's simply overwhelmingly good, and it's merely the baseline from which this generation of Corvette will be expanded.  While the Cadillac CT5-V Blackwing (more on that in a minute) is an amazing snapshot of GM's current performance standing and its little sibling so enraptured me that I went out and bought one, their existence is fleeting. Corvette will live on; forced-induction Cadillac sport sedans, not so much. So while all three are amazing machines when viewed in a vacuum, the Corvette stands above them as both a reflection of GM's current performance credentials and a signpost of what is to come. So, given the choice between the C8 and the 5V-Blackwing right now, I'd choose the C8. In 10 years, when the Blackwing is no longer in production and Corvette is in its 9th generation? Well, that might be a different story. Now, just pretend I said something even remotely that coherent when we get to the part of the video where I try to make an argument for the 5-V Blackwing as best GM car I've ever driven. Or just laugh at me while I ramble incoherently.