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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 Formula One-inspired Q60 Project Black S has been canned

Infiniti gave enthusiasts a preview of what a high-performance hybrid coupe equipped with Formula One-derived technology could look like when it released the Q60-based Black S concept in 2017. While executives hinted the 563-horsepower model could reach production sooner rather than later, the company confirmed it's been axed. Industry trade journal Automotive News learned the concept was consigned to the automotive attic from an Infiniti spokesman. He pointed out the design study "continues to inspire us," but he didn't explain why the Black S won't reach production. We're not surprised by the decision, though. It was a complex, eye-wateringly expensive version of a slow-selling model unveiled in 2015. Making the numbers add up was likely easier said than done.  Interestingly, many Infiniti dealers didn't want the Black S. "In today's market, a premium Japanese performance coupe has to be very low volume. Anything that Infiniti produces for its dealers, we want it to be a volume product. We're not really in the racing business. I would much rather see something like the QX60. That's a volume vehicle, that's where this company needs to go," opined Ed Lennon, the chairman of the Infiniti National Dealer Advisory Board, in an interview with Automotive News. Unveiled at the 2017 edition of the Geneva auto show, and presented again the following year in Paris, the Black S was powered by a gasoline-electric hybrid drivetrain built around the twin-turbocharged, 3.0-liter V6 that powers the Q60 Red Sport 400. It worked with three motor-generator units similar to the ones found in the Kinetic Energy Recovery System (KERS) fitted to Formula One cars. One spun the rear wheels, and the others were connected to the turbochargers to eliminate lag and deliver instant boost. Infiniti quoted a sub-four-second sprint to 60 mph. Hybrid technology adds weight, and Formula One-like components are no exception. Infiniti noted the drivetrain weighed 441 pounds more than the Red Sport 400's V6. Had it been built, the Black S would have relied extensively on carbon fiber to keep weight in check, and it would have offered a 50/50 weight distribution. Much has changed since 2017, however. Roland Krueger, the former Infiniti CEO who championed the project, left the company in January 2019 to lead Dyson's ill-fated automotive unit. Infiniti announced plans to exit the European market later that year, and it ended its participation in Formula One in 2020.

Infiniti Q50S getting G37's hydraulic steering for 2016

Sometimes, new technology doesn't make things better. Take the march of power steering technology as an example. Electrically assisted systems are in vogue at the moment for their ability to increase fuel efficiency, but tuning them to offer good feedback remains something of a dark art. Some automakers get it, but most don't. The previous hydraulically assisted setups just seem to be inherently more communicative when driven with enthusiasm. And it looks like Infiniti might be learning this lesson the hard way.
In talking with Keith St. Clair, the luxury brand's head of product planning, Car and Driver has learned that the Q50S is probably going to ditch its standard electrically assisted steering in favor of a hydraulic system derived from the old G37, a model soon to be renamed the Q40. The system should make the sedan more engaging behind the wheel, but it still won't help those who tick the option box for Infiniti's controversial Direct Adaptive Steering drive-by-wire system.
According to St. Clair, Infiniti's engineers have heard the complaints of critics and previous G37 owners about the Q50S model's electric steering system, and wanted to see what they could do. They didn't have to go far to figure it out - all it required was taking the steering rack off of a G37 and putting it onto the Q50S. After a little tweaking, "the car is a blast to drive," St. Clair reports. Now, the company is said to be fast-tracking the switch, and it could be ready for the 2016 model year.