2002 Nissan Xterra, Black 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.

Kaz and Shiro talk Gran Turismo 7 details, Titan Nismo and more in AMA

One of the greatest innovations to come about thanks to the gigantic popularity of Reddit is the Ask Me Anything (AMA) question and answer format. The AMA becomes especially worthwhile, of course, when the person(s) answering the questions have detailed information or insight on products we love.
So, in the case of the recent AMA session with Gran Turismo creator and mastermind Kazunori Yamauchi (above), and his buddy and Nissan chief designer Shiro Nakamura (right), it was basically must-read stuff.
The pair really lived up to our expectations, too, with Kaz offering a lot of useful information about the future of the Gran Turismo franchise (especially the upcoming GT7 for Playstation 4), and Shiro promising to bring some interesting new ideas back to his colleagues at Nissan.

2015 Nissan Pulsar and Pulsar Nismo Concept show Jekyll and Hyde for the hatch

Nissan is showing two very different sides of its new Pulsar five-door hatchback (on the right) at the 2014 Paris Motor Show. On one hand you get to see the standard version hoping to take the fight to popular European models like the Volkswagen Golf and Ford Focus, but also on the stage is our first glimpse at the Pulsar Nismo Concept (above) that demonstrates the vehicle's more devilish side.
The standard Pulsar is hoping to make a dent in the Euro C-segment ranks. It rides on the same platform as the Nissan Qashqai crossover and is actually about 2.4-inches longer than the Golf. Power comes from a trio of choices. There are 1.2-liter and 1.6-liter turbocharged gasoline engines with 113 horsepower and 187 hp, respectively, and a 1.5-liter diesel with 108 hp. CVTs are offered with them all. The Pulsar is also available with a variety of safety tech, including forward emergency braking, lane departure warning and blind spot monitoring.
However, the real excitement comes from the new Nismo Concept. Nissan is clear that it's "only a design study at this stage," but the sporty hatch imagines a flagship for the Pulsar range. It gets the full suite of Nismo goodies with a suspension dropped to the floor and sharper steering. The exterior also benefits from big air intakes in the front bumper, a rear diffuser with central exhausts, flared fenders and carbon fiber trim pieces. The whole thing is finished in satin gray with the division's traditional red trim. The interior has the same motif with race seats and a three-spoke steering wheel.