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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.

Infiniti puts EV plans on hold again

Think of it as the green-automotive industry's version of Groundhog Day. Nissan's Infiniti division is putting plans for its first mass-production electric vehicle on hold. Again. The Infiniti LE, whose concept version was unveiled 2012's New York Auto Show, is again being put up on the proverbial blocks, USA Today says, citing a presentation by Infiniti executive Michael Bartsch at a recent company event in Detroit. Essentially, the Nissan division has bigger fish to fry, in the form of boosting overall Infiniti sales, and doesn't yet want to put the effort into introducing the Infiniti LE. The Infiniti EV plans were first postponed by then-Infiniti President Johan de Nysschen during the summer of 2013, as de Nysschen wasn't quite buying into Nissan boss Carlos Ghosn's ambitious electric vehicle sales projections. De Nysschen resigned last summer to join General Motors' Cadillac division. One issue may be the fact that the Infiniti wouldn't be all that different from the Nissan Leaf. Despite the fact that US sales of that EV surged 34 percent last year compared to 2013, to 30,200 vehicles, an Infiniti version was apparently not enough of a selling point within the company. While the Infiniti is sportier looking than the Leaf and would boast inductive, wireless charging, it would have a similar power output and single-charge range as the Leaf.

Infiniti QX Sport Inspiration Concept fits perfectly in the QX50's shoes

If there was any doubt about whether the Infiniti QX Sport Inspiration Concept is a preview of the next QX50, the official details presented at the 2016 Beijing Motor Show should erase them. The concept is smaller – a lot smaller – than the last QX70. And despite a recent update to the QX50, the brand's midsize crossover is due for a new model. We're basing that statement on dimensions. The QX Sport Inspiration Concept rides on a 110.2-inch wheelbase, and is 181.1 inches long, 74.8 inches wide, and 65 inches high. The last QX50, meanwhile, rides on a 113.4-inch wheelbase, and is 186.8 inches long, 71.0 inches wide, and 62.7 inches high. Ignore the different lengths – the concept's front and rear overhangs are remarkably short and aren't likely to translate to production – but the wheelbase, width, and most importantly the height, present a footprint that's remarkably similar to the QX50. Combine that with our assessment of the QX Sport Inspiration Concept's styling, and it's a virtual certainty that we're looking at the QX50's successor. As we said yesterday, the high beltline, tight greenhouse, long hood, and aggressive headlights are all trademarks of both the QX50 and QX70. Infiniti didn't say what kind of engine is under this concept car's hood (if there even is one – it might just be an engineless shell), but we're almost certain it's something performance-oriented. That would prove true if and when a new production QX50 is unleashed. We're betting the company will opt for the increasingly familiar setup of the new 3.0-liter, twin-turbocharged V6, a seven-speed automatic transmission, and all-wheel drive, like what you can get on the Q50 Red Sport 400 and new Q60. With 300- and 400-horsepower versions of this engine available, it could signal an introduction of a two-tier QX50 lineup. We're getting ahead of ourselves, of course. The QX Sport is still only a concept, but Infiniti's latest information dump at the 2016 Beijing Motor Show serves as even stronger evidence that its CUV lineup will grow back to four vehicles sooner rather than later. Related Video: This content is hosted by a third party. To view it, please update your privacy preferences. Manage Settings.