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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.

Renault COO Tavares dreams of running GM or Ford

What do you do if you're in a job with no upward mobility? Admittedly, most of us just stick it out while secretly hoping our boss is sacked for all those paperclips he's been swiping, netting us a nice, shiny promotion. Then again, most of us aren't the number two at Renault, like Carlos Tavares.
Tavares is the right-hand man to Renault CEO, Carlos Ghosn, and like a lot of us, he's ready for another challenge. As Ghosn is only 59 years old and doesn't have a boss to fire him for paperclip theft, though, it's pretty unlikely that he'll be going anywhere anytime soon. Tavares doesn't seem too concerned, based on an interview he gave to Automotive News. "We have a big leader and he is here to stay," Tavares told AN.
What's surprising is where Tavares wants to go, "Why not GM? I would be honored to lead a company like GM." The Renault exec also mentioned Ford, and as AN points out, both organizations make a lot of sense. Both are led by CEOs that are approaching or are already past retirement age, and should be looking for dedicated replacements in the not-so-distant future. That doesn't mean Tavares is a shoe-in, though.

Roller coaster or racecar, which pulls more Gs?

Looking for a thrill? You're not the only one. You'll find kindred spirits at airfields going up for a skydive, atop bridges and towers with bungees attached to their feet and standing in line for roller coasters at the local amusement park. But you'll also find them in the paddock at the racing circuit.
So what's the commonality? G-force. It's like gravity, only in each of these cases, it's experienced by human invention. But which activity subjects your body to the greatest amount of g-force? That's what Nissan set to find out.
Before putting them back in the cockpit, Nismo sent out two of its young hot-shoes - Jann Mardenborough and Mark Shulzhitskiy - to an amusement park in the UK with a camera and a g-force meter to find out if any of the coasters could produce as much lateral gravitational force as an LMP2 racing car. See what they found in the pair of videos, below.