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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.

Nissan recalls over 120,000 Altimas due to... spare tire inflation?!

A pressure regulator that over- or underinflated spare tires for five days earlier this year has led to a recall of 123,308 units of the 2013 Nissan Altima. Sedans that were manufactured from March 21-26 are those possibly affected by the temporary tire snafu, the recall for which will begin on May 3.
Those notified of the issue can take their sedans to their local Nissan dealer, who will check the tire pressure and correct it if necessary, but we imagine owners can probably just whip out a tire gauge to check and adjust the inflation for themselves. Should you need it, there's an official notice from the National Highway Traffic Safety Administration below with a few more details.

CES 2020 and Carlos Ghosn | Autoblog Podcast #609

Welcome to a new decade of the Autoblog Podcast. In this week's episode, Editor-in-Chief Greg Migliore is joined by Senior Editor Alex Kierstein and Senior Editor, Green, John Beltz Snyder. First they talk about their early impressions of CES 2020 in Las Vegas, in particular how interesting Sony's Vision-S Concept is. Then they talk about the intriguing saga and daring escape of former Nissan boss and global fugitive Carlos Ghosn. After that, they turn their attention to what they've been driving, including the Genesis G70, Chevy Blazer and Hyundai Santa Fe. Finally, they help a listener pick a new fun toy to replace an unloved Porsche Cayman in the "Spend My Money" segment. Autoblog Podcast #609 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 CES 2020 And that excellent Sony Vision-S Concept What's going on with Carlos Ghosn? Cars we're driving:2020 Genesis G70 2.0T Sport RWD 2020 Chevrolet Blazer Premier AWD 2020 Hyundai Santa Fe 2.0T AWD Spend My Money Feedback Email – Podcast@Autoblog.com Review the show on iTunes Related Video: