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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.

Datsun to unveil second model later this month

Datsun, Nissan's new sub-brand for emerging markets, has announced plans to unveil its second model. Its first, the Go, was unveiled almost two months ago, and promised affordable, connected motoring for five in a handsome hatchback body. Datsun is following that up with a pair of new models for Indonesia.
The first of these two new vehicles will be shown on September 17 in Jakarta, eschewing the typical auto show debut. It's targeted at so-called "risers," the nickname for a group of highly aspirational customers in the Indonesian market. Datsun developed it locally with help from Nissan, and it'll cost under 100 million Indonesian rupiah (about $8,900 at today's rates).
We'll have the full boatload of information on the newest member of the Datsun family when it debuts on September 17. Scroll on to read the full press release from Datsun.

Nissan considering Rogue Hybrid for US

If Nissan can pull 48 miles per gallon out of a hybrid version of the Rogue we say "go for it" to the rumored discussions it may be considering just such a vehicle for the United States. The Japanese automaker is already gearing up to start selling the X-Trail (the JDM Rogue) in hybrid form in Japan. So why not the US? Indeed, the compact crossover may soon get a hybrid version here, Automotive News says, citing comments from Rogue chief engineer Nobusuke Toukura. The X-Trail Hybrid, which goes on sale in Japan next month, cuts nitrogen oxide emissions by 75 percent compared to the gas-powered version while offering more torque from of a smaller gas engine. The model, which sells in the $23,000-to-$27,000 range, also gets an impressive 48 mpg (on the more lenient Japan driving cycle). NIssan USA spokesman Brian Brockman said the company hadn't made any announcements regarding a possible Rogue Hybrid for the US and declined to comment further. The Rogue is Nissan's second-best-selling model in the US, behind the Altima. Through March, Rogue sales were up 28 percent from a year earlier to more than 64,000 units. While hybrids account for a far higher percentage of new vehicles in Japan than in the US, increased US fuel-economy standards combined with the model's popularity make the Rogue Hybrid a fairly logical next step for the model.