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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.

Nissan delays GT-R LM Nismo's return to WEC after poor Le Mans showing

After a catastrophic run at the 24 Hours of Le Mans in June and a widely publicized review of the program, Nissan is delaying the GT-R LM Nismo prototype's next showing in the World Endurance Championship season. The team will continue testing and working out the car's crippling issues. "We know people will be disappointed, but be assured that nobody is more disappointed than us," Shoichi Miyatani, the president of Nismo, said in a statement. "We are racers and we want to compete, but we also want to be competitive. That is why we have chosen to continue our test program and prepare the GT-R LM Nismo for the strong competition we face in the World Endurance Championship. When you innovate, you don't give up at the first hurdle. We are committed to overcoming this challenge." The big issue for the GT-R at Le Mans was its Energy Recovery System. Its failure meant the racer was forced to rely on engine power alone, hobbling the program significantly. "We have many areas to work on – not least ensuring that we have the best ERS option available to us. The team is pushing hard on track, in the wind tunnel and at Nismo's various facilities around the world to deliver the long list of improvements we know that we need," Ben Bowlby, Nissan LM P1 technical director, said in a statement. The GT-R was met with skepticism upon its debut, thanks to the way it eschewed the hallmarks of most successful racers. Not only was the engine in front – a rarity in the past four or so decades of prototypes – but it also sent its power to the front wheels. And it was a lot – 1,250 hp to be precise, with 700 hp coming from electric motors alone. Despite this frankly absurd output, the competition from Porsche, Audi, and Toyota easily bested the GT-R LM Nismos. Scroll down for the official press release from Nissan. Nissan to address technical issues of LM P1 car before returning to World Endurance Championship Nissan GT-R LM NISMO to remain in test program before re-joining World Endurance Championship LONDON – Nissan today announced that it will delay its return to the LM P1 class of the FIA World Endurance Championship and instead focus on technical issues that challenged its race team during the Le Mans 24 Hours. Issues with the energy recovery system (ERS) meant that Nissan had to run at the Le Mans 24 Hours on engine power alone.

Autoblog Podcast #416

Episode #416 of the Autoblog Podcast is here, and this week, Dan Roth, Steven Ewing, and Brandon Turkus talk about the 2016 Mazda MX-5 Miata, seeing the 2016 Nissan Maxima in the company's Super Bowl ad, and GMC's potential plans for a Jeep Wrangler fighter. Of course, the podcast starts with what's in the garage and finishes up with some of your questions, and for those of you who hung with us live on our UStream channel, thanks for taking the time. Check out the rundown with times for topics, and you can follow along down below with our Q&A. Thanks for listening! Autoblog Podcast #416 Topics 2016 Mazda MX-5 Miata first drive 2016 Nissan Maxima previewed in Super Bowl ad GMC mulling Jeep Wrangler fighter In The Autoblog Garage 2015 Hyundai Genesis 5.0L V8 2015 Honda CR-V Long-Term 2015 Volkswagen GTI Hosts: Dan Roth, Steven Ewing, Brandon Turkus Runtime: 01:36:43 Rundown Intro and Garage - 00:00 Maxima – 30:48 Miata – 41:46 GMC/Wrangler – 59:14 Q&A - 01:11:13 Get The Podcast UStream – Listen live on Mondays at 10 PM Eastern at UStream iTunes – Subscribe to the Autoblog Podcast in iTunes RSS – Add the Autoblog Podcast feed to your RSS aggregator MP3 – Download the MP3 directly Feedback Email – Podcast at Autoblog dot com Review the show in iTunes Podcasts GMC Honda Hyundai Jeep Mazda Nissan Volkswagen vw gti nissan maxima