2014 Nissan Murano Crosscabriolet Base on 2040-cars

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Submit your questions for Autoblog Podcast #305 LIVE featuring Matt Edmonds of the Tire Rack!

We record Episode #305 of the Autoblog Podcast tonight, and we'll be joined by Matt Edmonds of podcast sponsor The Tire Rack, so drop us your questions and comments via the Q&A module below, especially if they have to do with tires and wheels! Subscribe to the Autoblog Podcast in iTunes if you haven't already done so, and if you want to take it all in live, tune in to our UStream (audio only) channel at 10:00 PM Eastern tonight.
Discussion Topics for Autoblog Podcast Episode #305
2014 Chevrolet Silverado

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.

What happens to Renault-Nissan after Ghosn is gone?

Carlos Ghosn is a very, very busy man. Like, really busy. As in, he heads up three automakers (and their subsidiaries), running facilities in 68 countries and selling vehicles in 170 different markets across the globe. He flies over 300,000 miles per year and works 15 to 16 hours a day, just to manage an alliance between the Japanese and French that's responsible for an expected $140 billion in sales this year alone. The Chairman and CEO of the Renault-Nissan Alliance, Ghosn has managed a number of remarkable feats during his time at both automakers, but there are some that are questioning how much longer the 60-year-old exec can handle the punishing nature of his responsibilities. According to Fortune, six months ago Ghosn signed a four-year contract to continue running Renault, while his tenure at Nissan will continue until at least 2017. Beyond that, though, the future is rather murky, and it's made worse by the high-level turnover that Renault-Nissan has experienced over the past few years, losing execs like Carlos Tavares, Johan de Nysschen and Andy Palmer. Fortune has an excellent, and lengthy, feature on Ghosn, his responsibilities and the danger posed to Renault-Nissan by his departure. If you're at all curious about what the exec has done for the two automakers, how this alliance has worked when so many other industry partnerships have failed and just what a post-Ghosn future may hold, head over and have a look. News Source: FortuneImage Credit: Lee Jin-man / AP Hirings/Firings/Layoffs Read This Infiniti Nissan Renault datsun dacia lada readthis