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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.

Infiniti Q60 Project Black S packs F1-derived hybrid twin-turbo V6

At the 2017 Geneva Motor Show, Infiniti unveiled the Project Black S, a souped-up version of the Q60 coupe that packed technology derived from the Renault Sport Formula 1 Team's race cars. Details were scarce. Aside from some F1-inspired bodywork, all we knew was that the twin-turbo V6 would be paired with a kinetic energy recovery system, or KERS for short. At next week's Paris Motor Show, Infiniti is bringing a new concept that's a bit more polished as well as some additional details about what rests under the hood. The car is still dubbed the Infiniti Project Black S. The car still packs a twin-turbocharged 3.0-liter V6 paired with an energy recovery system. Infiniti claims the car makes 563 horsepower, up from 400 in the Q60 Red Sport 400. The Project Black S should hit 60 mph in fewer than four seconds. The powertrain uses three motor generator units (MGU) and a single MGU-K that harvests brake energy. Two electric turbochargers harvest heat energy from the exhaust, meaning the car can gain energy both under braking and acceleration. Visually, there's not much that's changed from last year's Geneva concept. We only have one new photo, but to our eyes the only difference is a few yellow accents on the front bumper. We'll have to wait until next week's reveal for more photos. Related Video:

Nissan Recalls More Than One Million Vehicles For Air Bags

Nissan is recalling just over one million cars, SUVs and vans because the front passenger air bags may not inflate in a crash. It's the company's second recall to fix the same problem. The recall affects the Altima midsize car, Leaf electric car, Pathfinder SUV and Sentra compact models from the 2013 and 2014 model years, as well as the NV200 Taxi van and Infiniti JX35 SUV from 2013. Also covered are the Infiniti QX60 and Q50 SUVs from 2014. In documents filed with the National Highway Traffic Safety Administration, Nissan says the vehicles' computer software may not detect an adult in the passenger seat. If that happens, the air bags won't inflate. Nissan will notify owners and dealers will update the software for free. The recall is expected to start in mid-April. Most of the vehicles were recalled in February of last year for a similar problem. Dealers replaced seat sensors, but Nissan said it continued to get consumer complaints and warranty claims in vehicles that had been repaired. Front passenger seats have sensors that determine the passenger's weight and turn off air bags off if a child is on board. The malfunctioning sensors can turn the air bags off even if an adult is in the seat. Nissan received three reports of air bags failing to inflate in a crash. Spokesman Steve Yeager said in an e-mail that he is not sure if anyone was hurt in those incidents. There have been no deaths due to the problem, he said. The recall affects almost 990,000 vehicles in the U.S., another 60,000 in Canada and small numbers in other countries, Yeager said. Related Gallery Nissan Searches For Identity In America