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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 nearly 20,000 NV vans over gearshift issue

Nissan is recalling 18,800 NV vans built between December 20, 2010 and January 4, 2013. Certain 2012 and 2013 models equipped with a steering-column-mounted transmission shift levers may have been built with improperly installed shift mechanisms.
If the NV's gear selector plate lock clip wasn't installed correctly, normal road vibration could result in a gear position indicator that does not match the actual gear selection. As a result, when the driver selects 'park,' the transmission could still be in gear or in neutral, and roll away. The National Highway Traffic Safety Administration says this condition greatly increased the risk of accident and injury.
Nissan will inspect the gear selector lock clip and replace the part if necessary free of charge. Owners can expect to be notified once the recall campaign begins on April 8, 2013. Read the full recall notice below for more information.

Nissan Xterra's fate hangs in the balance

The Nissan Xterra might not be long for this world, according to a report from Edmunds. The rugged SUV, which has always been a bit more of a hardcore, purpose-built vehicle than the rest of the Nissan SUV range. But it has also suffered from slowing sales, low fuel economy relative to the competition and general neglect, as Nissan has focused on other offerings in its range.
"There are plans to replace it, there are always plans, (but) I am not sure it will happen. I would say in the next six months to a year," Pierre Loing, vice president of product planning for Nissan Americas told Edmunds. Part of the problem, he added, was that the Xterra is a US-only vehicle, which makes it a hard sell in a world where automakers are increasingly depending on global cars.
Besides the economic forces working against the Xterra, it's just a vehicle that hasn't been a huge sales success of late. Customers are more conscious of fuel economy and a body-on-frame SUV that only nets 16 miles per gallon just isn't good enough; arguably why Nissan barely sold 17,000 units last year. We can hold out hope, as the Xterra remains a fun off-roader that we'd hate to see go, but unless Nissan finds a business case or some global partners, this is a vehicle that is on its last leg.