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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's Carlos Ghosn taps the brakes on autonomous car progress

"Self-driving cars remain a long way from commercial reality."
Nissan CEO Carlos Ghosn shocked the automotive industry last year when he announced that his company plans to offer consumers an autonomous car by 2020. The automaker even showed off its self-driving Leaf prototype as proof. He was bolder recently with the pronouncement that select markets could have them in 2018, if laws allowed. The boss' optimism appears to be waning, though, and he's now sounding a lot more conservative about the future. While driverless vehicles are still on the way, Ghosn is hedging his bets with a more gradual implementation of several systems.

Nissan won't downsize the next Armada

The Nissan Armada is aptly named, because in relative automotive terms, it's not just the size of a ship - it's the size of a whole fleet. And that, according to reports, isn't about to change.
While many of the larger SUVs on the market are gradually being phased out or replaced by smaller crossovers, Nissan apparently plans on keeping the Armada right where it is. And that means a large, truck-based, eight-passenger colossus, because there are buyers out there who expect no less and Nissan isn't about to lose them to the likes of the Toyota Sequoia, Ford Expedition and Lincoln Navigator, or a General Motors lineup that includes the Chevy Suburban and Tahoe, GMC Yukon and Cadillac Escalade.
That doesn't mean that the next Armada - which Edmunds expects will arrive in 2015 or 2016 - will be immune to constricting environmental regulations, so Nissan will have to get creative. A vehicle the size of the Armada has all the aerodynamic efficiency of the side of a barn, but Nissan is reportedly aiming to streamline that in order to boost efficiency, for starters.