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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 leaning on JATCO to remedy CVT problems

Nissan's decision to fit continuously variable transmissions across even more of its new models may be coming back to bite the Japanese automaker, as it's been hampered by customer satisfaction issues relating to its XTronic CVTs, which are provided by a supplier called JATCO.
From what we're understanding, the issue largely relates to customers' unfamiliarity with the non-traditional shift nature of a CVT. Dealers have reported complaints and service visits from owners over the belt-driven automatics (did these people not test drive the cars before they bought them and notice that they don't shift conventionally?).
The company, which Nissan owns 75 percent of, has come under fire from none other than Nissan CEO Carlos Ghosn, who's spoken about JATCO and its troubles rather openly. "Every time you launch a new CVT you always have some risks," Ghosn said in an interview with Automotive News. "So we now have a process by which, before we launch any new CVT, [JATCO] come before the Nissan executive committee to explain all the measures they have taken to make sure there are no surprises."

2013 Nissan GT-R and 2013 Alpina B6 mix it up on track and street

Here we have Autocar making an unforeseen comparison: the Nissan GT-R against the Alpina B6 at Brands Hatch and on public roads. Steve Sutcliffe clobbers the circuit in the 3,828-pound, all-wheel-drive sports car, then sees how well the 4,114-pound, rear-wheel drive grand tourer does against it.
Sutcliffe says there are quite a few similarities between the two cars, but that's really only on the spec sheet. The Nissan's got two turbos attached to its 3.8-liter V6, 542 horsepower and 465 pound-feet of torque. The Alpina's got two turbos attached to its 4.4-liter V8, 532 hp and 528 lb-ft. But one's brief is to be a monster on the track, the other on the boulevard, and if there's anything the video demonstrates, it's each car's focus.