2016 Infiniti Qx60 New Tires on 2040-cars

Auto blog

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.

Popular Science magazine's Best Of What's New 2012 all ate up with cars

Popular Science has named the winners in its Best of What's New awards, the victors coming in the categories of aerospace, automotive, engineering, entertainment, gadgets, green, hardware, health, home, recreation, security and software. The automotive category did not go wanting for lauded advancements:
Tesla Model S: the Grand Award winner for being "the standard by which all future electric vehicles will be measured."
BMW 328i: it's 2.0-liter turbocharged four-cylinder gets called out for being more powerful and frugal than the six-cylinder it replaces.

New details emerge on Inifiniti QX50’s unique new variable-compression engine

Infiniti will release the world's first production variable-compression engine when it releases the 2019 QX50 midsize SUV sometime next year. Now we have some new details on the innovative new engine, which Infiniti is calling VC-T, for Variable Compression Turbo, after the luxury brand offered a prototype test drive. We wrote extensively about the complicated technology underpinning the new engine last year. It's the latest novel development that could represent a range-extender, if you will, for the embattled internal combustion engine in an era when automakers and governments are shifting their focus to electric vehicles. The VC-T is a new inline-four, 2.0-liter that combines the power of a high-performance turbo gasoline engine with the torque and efficiency of an advanced diesel engine, but without the latter's notorious emissions. It features the ability to seamlessly raise or lower the stroke of the pistons in the combustion chamber, depending on the driving conditions it detects and inputs from the driver, to select the best compression ratio—anywhere between 8:1, typical for high-performance engines, and 14:1 for high efficiency. In essence, it delivers the performance of a V6 but is much more efficient, with improved fuel efficiency of between 10 to 15 percent with its best competitors, per Car and Driver. You can view how it works in motion via the video below. This content is hosted by a third party. To view it, please update your privacy preferences. Manage Settings. It's also quieter, more lightweight and compact than V6 engines with comparable power outputs, estimated at 268 horsepower and 288 pound-feet of torque. In a prototype test drive, Car and Driver writes that the engine "felt very conventional" and responsive, with strong and smooth acceleration. "The only indication you have that the compression ratio is changing is from an indicator in the instrument cluster next to the boost gauge." The engine is expected to deliver fuel economy gains of 27 percent in combined city-highway EPA rating over the outgoing QX50, which had a 3.7-liter V6. The 2019 model, fitted with the VC-T, should get about 26 mpg in combined fuel economy, and it will get to 60 mph almost one second faster than its four-cylinder counterparts, Nissan's chief powertrain engineer, Shinichi Kiga, told Automotive News. The VC-T engine is the result of 20 years of development spanning more than 100 prototypes and around 300 patents at Nissan.