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Infiniti's new VC-T changes the rules of small turbocharged engines

The upcoming Infiniti QX50 crossover does not get our pulse racing, no matter how shapely the QX Sport Inspiration concept that previews it may be. No midsize SUV does, to be fair. But it has something special under the hood – the world's first production variable-compression-ratio engine. That means the QX50's 2.0-liter turbo four, which makes 268 horsepower and 288 pound-feet of torque, will have up to 27 percent better fuel economy. Here's how it works. The trend of moving to smaller, turbocharged engines carries with it one big falsehood. Under low load when the turbo isn't needed, these engines are less efficient than an equivalent engine without a turbo because of the low compression ratio the turbo requires. That is, if you never need the extra power, you're wasting fuel. Turbocharged (and supercharged) engines use a lower compression ratio to prevent detonation. When you force extra air in a cylinder and mix it with fuel, it's more likely to prematurely go boom. Lowering the compression ratio prevents this problem, but it's less efficient. Infiniti's VC-T promises the best of both worlds, with a compression ratio that ranges from 8.0:1 for high-power turbo needs to a 14.0:1 ratio for fuel-sipping efficiency. At its heart the VC-T engine is a simple idea, but it's complicated to explain. Consider yourself warned. The photo below from Infiniti serves as a good visual overview. For the truly nerdy, this patent application covers the mechanical concept. Instead of having the pistons connected to the crankshaft, Infiniti's engine has a pivot arm with a connection on each end. One end connects to the piston, the other connects to a second lower shaft, which is controlled by an actuator arm. At any given time the engine's pistons move up and down according to the lobes on the crankshaft. But the actuator arm can change the angle of the pivot arm up and down. That is, the pistons still move in the same motion with the same stroke, but phase the entire stroke up or down. Move the pivot up and there's less room at the top, which means a higher compression ratio. Move the pivot down and the compression ratio goes down, too. As an added bonus, the lower shaft eliminates the need for counter-rotating balance shafts. Infiniti says this system works constantly and can vary the compression ratio to any number between 8:1 and 14:1. It also uses electronic variable valve timing on the intake valves to switch into Atkinson-cycle combustion for greater efficiency.

Porsche wins the 2015 24 Hours of Le Mans

The question going into this year's 24 Hours of Le Mans was whether or not the Porsche 919 Hybrid would be able to combine its qualifying pace with race reliability. After battling neck-and-neck with Audi's R18 for most of the race, the answer is a resounding yes. Not only did Porsche drivers climb the first two spots on the podium, they did so without any major mishaps on track. This win is the first overall trophy for Porsche since 1998. Audi previously won the last five races, and 13 of the last 15. Corvette also returned to the winner's circle, with the No. 64 C7.R taking winning the GTE Pro division. The victory is the first class win for Corvette since 2011. KCMG won the LMP2 class in ninth overall. With 45 minutes to go the No. 98 Aston Martin crashed out of first place in GTE Amateur, giving the class win to SMP Racing's Ferrari and second place to the Patrick Dempsey Racing Porsche 911 RSR. For the full list of official results, click here. The GTE Pro class proved to be just as exciting as the P1 class, with a four-way battle for first after four hours into the race. For most of the race, the battle at the top went back and forth between the two German manufacturers. An tire puncture in the No. 7 Audi gave up the lead to Porsche, and moments later a crash forced the No. 8 into the garage. But a three-minute replacement of the front and rear bodywork kept the Audi in contention. As the race wore into the night, Porsche maintained a slightly faster pace than Audi. Nick Tandy took the lead on Lap 253 early Sunday morning, and car No. 19 never gave up the top position. The win is the first for all three drivers of the No. 19 – Nico Hulkenberg, Earl Bamber, and Nick Tandy. A lap behind in second was the No. 17 Porsche. The Audis fought reliability problems late in the race but still finished third with the No. 7 R18. The GTE Pro class proved to be just as exciting as the P1 class, with a four-way battle for first after four hours into the race. As the Aston Martin cars dropped away, the lone Corvette Racing entry took over, followed by a charging AF Corse team Ferrari 458 Italia. The Corvette and Ferrari continued to trade places in the final hours until gearbox trouble forced the No. 51 Ferrari out of contention. It was eventually passed by the other AF Corse car, No. 71. Nissan experienced all the pain of a first-year effort with its front-wheel-drive GT-R LM Nismo.

Nissan Leaf and the future of auto shows | Autoblog Podcast #525

Related: We obsessively covered the Frankfurt Motor Show — here's our complete coverage On this week's Autoblog Podcast, Editor-in-Chief Greg Migliore is joined by Associate Editor Joel Stocksdale. The pair discuss the long-awaited reveal of the second-generation Nissan Leaf as well as the Alfa Romeo Giulia and BMW M550i that recently passed through the office. They also preview the 2017 Frankfurt Motor Show and discuss the future and relevance of auto shows. The rundown is below. Remember, if you have a car-related question you'd like us to answer or you want buying advice of your very own, send a message or a voice memo to podcast@autoblog.com. (If you record audio of a question with your phone and get it to us, you could hear your very own voice on the podcast. Neat, right?) And if you have other questions or comments, please send those too. Autoblog Podcast #525The video meant to be presented here is no longer available. Sorry for the inconvenience.Get The Podcast iTunes – Subscribe to the Autoblog Podcast in iTunes RSS – Add the Autoblog Podcast feed to your RSS aggregator MP3 – Download the MP3 directly Topics and stories we mention Rundown Nissan Leaf reveal Frankfurt Motor Show preview What we're driving: Alfa Romeo Giulia and BMW M550i Unpopular opinion: the relevance of auto shows Spend my money Feedback Email – Podcast at Autoblog dot com Review the show on iTunes Image Credit: BMW, Nissan Green Podcasts Frankfurt Motor Show Alfa Romeo BMW Nissan Hatchback Electric Luxury Sedan alfa romeo giulia