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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 226k vehicles over airbag inflators

Nissan and Infiniti are the latest automakers to issue recalls involving faulty airbag inflators from Takata. The Japanese automakers have announced campaigns covering about 226,326 units from seven models built in the early 2000s because they contain the bad part in the passenger-side, front airbag. The affected vehicles include the 2002-2004 Nissan Sentra, 2002-2003 Pathfinder and 2002-2003 Maxima, and it also covers the 2002-2003 Infiniti QX4, 2002-2003 I35, 2003 FX45 and 2003 FX35.
Like the other vehicles with the faulty inflators, it's possible for the part to rupture during airbag deployment and spray metal shrapnel at occupants. Nissan and Infiniti have even included vehicles with replacement airbags in this campaign because those parts also could have been defective. Both companies were also part of the earlier regional campaign to fix cars in high-humidity climates where the problem has been found to be the worst.
As is the usual response, Nissan and Infiniti will notify owners of the affected vehicles and will make the repair at no charge. According to the filing with the National Highway Traffic Safety Administration, these fixes will commence around August 11. Scroll down to read the report from NHTSA, or read the full defect notice as a PDF, here.

Renault-Nissan debuts new Common Module Family for future vehicles

Platform sharing is nothing new for the 14-year-old Renault-Nissan Alliance, but this partnership is set to introduce new modular platform components that will eventually underpin 11 Renault models and three Nissan vehicles by 2020. Rather than being a typical platform, the Common Module Family (CMF) actually represents five segments of a platform that can be used in various applications, and one of the first vehicles to use this architecture will be the 2014 Nissan Rogue (spy shots of which are shown below) when it arrives "in late 2013."
As pictured in the image above (click to expand), CMF is composed of four chassis component, principally the front underbody, rear underbody, engine bay and cockpit as well as a common electrical system. Besides the next-gen Rogue, future Nissan models to share CMF will include the Qashqai and X-Trail, while Renault models will start using the platform next year on vehicles including the Scénic and Laguna. The CMF architecture is expected to help the Alliance reduce the parts cost of a vehicle by up to 30 percent and reduce the entry cost by up to 40 percent. The official press release with more details about CMF, and what it means for Renault-Nissan, is posted below.