2017 Infiniti Q50 Premium on 2040-cars

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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.

Submit your questions for Autoblog Podcast #344 LIVE!

We're set to record Autoblog Podcast #344 tonight, joined by Doug DeMuro, author of Plays With Cars, formerly of Porsche Cars North America, and all-around swell guy. You can drop us your questions and comments via our Q&A module below, and we'll give them extra-diligent attention. Subscribe to the Autoblog Podcast in iTunes if you haven't already done so, and if you want to take it all in live, tune in to our UStream (audio only) channel at 10:00 PM Eastern tonight.
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Nissan, Kia under investigation over occupant detection systems

Kia and Nissan are facing separate investigations by the National Highway Traffic Safety Administration because of alleged problems with the occupant detection systems in their vehicles' airbags. The larger investigation is NHTSA's new engineering analysis into 986,826 Nissan and Infiniti vehicles. They include the 2013 Nissan NV200 and 2013-2014 Altima, Leaf, Pathfinder, and Sentra. Among the Infinitis, there are the 2013 JX35 and 2014 Q50 and QX60. Owners allege the occupant classification system can misidentify passengers and turn off the airbag if they don't weigh enough. Nissan recalled over a million vehicles worldwide last year to fix the same problem with a software update, but NHTSA kept getting complaints about the issue after the repair. The agency opened a preliminary evaluation in March, and after 1,271 complaints it has now been updated to an engineering analysis. The Feds intend to evaluate the effectiveness of Nissan's solution. NHTSA is also opening a preliminary evaluation into the 2007-2009 Kia Spectra for the occupant classification not working properly, and it could affect an estimated 186,000 of these vehicles. The government agency has 43 complaints from people allegedly reporting the failures. According to NHTSA, the issue could result in the airbag not deploying with enough force or not activating at all in an accident. This investigation is meant to assess the scope of the potential flaw, and there's no recall yet. INVESTIGATION Subject : Occupant Classification System Fault Date Investigation Opened: SEP 01, 2015 Date Investigation Closed: Open NHTSA Action Number: PE15031 Component(s): AIR BAGS All Products Associated with this Investigation Vehicle Make Model Model Year(s) KIA SPECTRA 2007-2009 Details Manufacturer: Kia Motors America SUMMARY: The Office of Defects Investigation (ODI) has received 43 complaints alleging a malfunction of the front passenger seat occupant classification system (OCS) in 2007-2009 Kia Spectra vehicles. The complaints report illumination of the SRS (air bag) warning light. All of the complaints allege the cause of the light illumination to be a malfunction of the OCS sensor mat imbedded in the passenger seat cushion, and/or report the presence of diagnostic trouble code B1448 which relates to the OCS sensor mat also. Many of the complaints note the malfunction occurred after the warranty period expired and mention high repair costs as a major deterrent to repairing the vehicle.