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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.

2013 Nissan Leaf [w/video]

If It Ain't Broke, Don't Fix It
Look at the 2013 Nissan Leaf - even one parked next to a 2012 model - and you'll be hard-pressed to spot the differences. Changes and updates have been made, but you have to know the details to tell. It's sort of like listening to a hipster tell you why Interpol and The National have completely different sounds.
Nissan says it didn't reinvent the Leaf because what the company has created is working. Over 25,000 Leafs have been sold in the US - 62,000 around the world - since the car went on sale in late 2010. That may not sound like a lot, but it's heads and shoulders above any other all-electric car available anywhere. The car has its detractors - boy, does it ever - but Nissan knows it's hard to argue with real-world success.

Nissan says next Rogue coming September 10

The Nissan Rogue has been around since 2007, and after nearly seven years on the market, it's about due for replacement. Which is just what Nissan has announced is coming up next down the pipeline.
The Japanese automaker didn't reveal much to go with this teaser image of the headlight and front fender, saying only that "the all-new 2014 Nissan Rogue will push the envelope of CUV design starting on September 10 when it is unveiled." That's the day on which the Frankfurt Motor Show opens its doors for press previews, so it's pretty safe to say that we'll be seeing it at the Messe.
The news follows the spy shots we brought you two weeks ago. Expect the design to follow the lead set forth by the Hi-Cross concept from Geneva last year, with production to take place in Tennessee.