2006 Nissan 350z Touring Coupe 2-door 3.5l on 2040-cars

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Submit your questions for Autoblog Podcast #305 LIVE featuring Matt Edmonds of the Tire Rack!

We record Episode #305 of the Autoblog Podcast tonight, and we'll be joined by Matt Edmonds of podcast sponsor The Tire Rack, so drop us your questions and comments via the Q&A module below, especially if they have to do with tires and wheels! 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.
Discussion Topics for Autoblog Podcast Episode #305
2014 Chevrolet Silverado

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.

2014 Nissan Rogue

The compact crossover segment is crowded because it offers near-perfect transportation for small families and empty nesters alike. As more and more consumers discover the benefits of compact crossovers - riding tall in traffic, enjoying four-cylinder fuel economy and the confidence of all-weather traction - automakers are jumping into the game to meet the increasing demand. Today's choices, in no particular order, include the Honda CR-V, Jeep Cherokee, Mazda CX-5, Hyundai Tucson, Mini Countryman, Subaru Forester, Kia Sportage, Volkswagen Tiguan, Ford Escape, Mitsubishi Outlander, Toyota RAV4 and this Nissan Rogue. Nearly all start around $22,000 in base trim and work their way reasonably upwards with more appealing trim levels and options. If you spend much over $33,000 in this segment, you are a glutton for frosting.
The latest player from Nissan is its all-new second-generation Rogue, introduced late last year as a 2014 model. After a brief First Drive in October, we recently welcomed back the Rogue for a week-long review. The plan was to embed the compact crossover into a family routine during the holidays, where it would receive a hearty workout hauling everything from five adult passengers and their shopping bags to trays loaded with warm honey-glazed hams and pecan pies for a dinner party. The compact CUV handled all with poise, but everything wasn't as sweet as its edible cargo.