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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

MotorWeek looks back at 1995 Chevy Tahoe, GMC Yukon

MotorWeek's Retro Review series gives us a nostalgic look back at some of the best sports cars and luxury sedans available in the 1980s and '90s. For its latest clip, the show shifts gears to remember the 1995 Chevrolet Tahoe and GMC Yukon. Similar to the success of crossovers today, SUVs were tallying big sales and making big money for automakers in the mid-'90s. The Tahoe and Yukon filled slots in the market as steps down from the larger Suburban. These twins weren't wanting for space, though, with plenty of room to haul around a family. MotorWeek came away generally impressed too, and called the models some "of the better riding sport utilities we've ever experienced." This review comes with some jazzy, electric guitar licks to enjoy in the background.

Race Recap: Rolex 24 at Daytona was fast and feisty

Let the record show that victory at the 2015 Rolex 24 at Daytona went to the No. 02 Chip Ganassi Racing with Felix Sabates Target/Ford EcoBoost Riley DP driven by Verizon IndyCar drivers Scott Dixon and Tony Kanaan and NASCAR drivers Jamie McMurray and Kyle Larson. The winner did 740 laps to cover 2,634.3 miles in 24 hours and 57.667 seconds. That's a statement to this year's pace in spite of 18 cautions, two more than last year: the Michael Shank Racing Ligier got pole with a time of 1:39.194, slower than last year's pole time of 1:38.270; however, the winning car last year only did 695 laps. The fight for top honors was shaved to a four-car battle over the first third of the event. The No. 02 Ganassi car took the lead on the first lap, swapping it well into the night with the No. 01 Ganassi car, the No. 10 Wayne Taylor Racing Corvette DP, and the defending champion No. 5 Action Express Corvette DP, all of them staying within about 20 seconds of one another. The Action Express car had a fuel connector come loose and lost three laps getting towed back to the pits to have it reattached, but was back in the lead 18 hours in. The No. 01 Ganassi car dropped out with recurring clutch problems 22 hours in, retiring not long after. A race-within-the-race is where the concluding action happened, a seven minute, 30-second dash from the end of the last caution to the checkered flag. During the penultimate pit stops with an hour to go, Dixon was in second place followed Jordan Taylor in the Wayne Taylor Racing DP into the pits but beat him out, taking the lead. The Action Express car was in third. In the last pit stops of the race, Dixon gained even more time, getting a four-second advantage over Taylor. Then a full-course caution came out twenty minutes before the finish when a Prototype Challenge car hit the wall and caught fire, bunching up the field. That closed the pits, but the Wayne Taylor Racing car had to pit during that yellow because of a miscalculation of driver time. No driver can be behind the wheel for more than four hours in a six-hour period but Jordan Taylor was going to go over, so he came in to swap out for brother Ricky. That cost the team any chance of second place, since they took an additional drive-through penalty for entering closed pits. When the track went green again, Sebastien Bourdais in the Action Express car stayed all over Dixon for the final five laps but couldn't get around him.