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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.

2018 Mazda6, Porsche Panamera and Nissan Titan | Autoblog Podcast #541

On this week's Autoblog Podcast, Editor-in-Chief Greg Migliore is joined by Green Editor John Beltz Snyder and Associate Editor Reese Counts. We talk about driving the updated, turbocharged 2018 Mazda6, 2018 Porsche Panamera Sport Turismo 4S Sport Turismo and the 2018 Nissan Titan S 4x4 King Cab. We also discuss aftermarket parts for the Chevy Colorado, pick our favorite 50th Anniversary Hot Wheels and, as always, help a listener buy a new car in our "Spend My Money" segment. Autoblog Podcast #541 Your browser does not support the audio element. 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 Rundown Cars we've been driving: Mazda6, Porsche Panamera, Nissan Titan The aftermarket takes on the Chevy Colorado 50th Anniversary Hot Wheels Spend my money Feedback Email – Podcast@Autoblog.com Review the show on iTunes Related Video: Aftermarket Podcasts Chevrolet Mazda Nissan Porsche Car Buying Truck Wagon Sedan Hot Wheels porsche panamera sport turismo

Renault, Nissan limit French government interference

Renault and Nissan are taking action to limit the influence that one can exercise over the other's operations. The measures, announced by both automakers after meetings of their respective boards in Paris and Tokyo, aim to keep each other at arm's length. But more than that, they seek to cap the degree of influence which the French government can bring to bear on either automaker. The steps are being taken in response to investment moves by the French state. While the government's investment arm – known as the Agence des Participations de l'Etat (or state participation agency) – previously controlled 15 percent of Renault's shares, it increased its holdings this April to 19.73 percent. The action sparked concerns at Renault that the French government would attempt to dictate operating procedures to both automakers, potentially to favor production in France over other locations. Given that Renault holds a 43-percent stake in Nissan, the Japanese automaker grew concerned over potential French state interference as well. To assuage those concerns, Renault, Nissan, and the French government came to an agreement with three vital clauses. Most importantly, despite its nearly 20-percent holdings, the French government will be granted only 17.9 percent of voting rights in Renault (to be extended up to 20 percent under certain exceptional circumstances). Renault (and by extension the French government) will also be prevented from interfering in Nissan's governance. With those measures in place, Nissan will not seek more voting rights based on the 15-percent stake which it, in turn, holds in Renault. Having successfully concluded the deal and hedged against the threat of government interference, the Renault board reasserted its confidence in Carlos Ghosn. Through the unique terms of their alliance, Ghosn serves as chairman and CEO of both Renault and Nissan. The two cooperate closely and share resources extending far beyond their chief executive, but remain distinct companies rather than merge, as Fiat and Chrysler have. Renault Board approves alliance stability covenant between Renault and Nissan As early as 16th April 2015, the Renault Board of Directors unanimously reiterated that the sustainability, success and resilience of the Alliance since its very inception in 1999 were based on a balance of shares held by Renault and Nissan.