2002 Nissan Sentra Gxe Sedan 4-door 1.8l 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.

Autoblog Podcast #317

Mitsubishi Mirage, Toyota thinks of beefing up US production, Marchionne on Alfa, Dart and minivans, Ford Atlas concept, Honda Gear concept
Episode #317 of the Autoblog Podcast is here, and this week, Dan Roth, Jeff Ross and Michael Harley bookend the other podcast topics with a pair from the Montreal Auto Show, the Mitsubishi Mirage and Honda Gear concept, and in between we talk about Toyota building all its US-market cars stateside, Hyundai building a Nurburgring test facility, Sergio Marchionne's latest words about Alfa Romeo, Dodge Dart powertrains and the future of Chrysler vans. Some chatter about the Ford Atlas concept finishes up the meat of the 'cast and then we wrap with your questions. For those of you who hung with us live on our UStream channel, thanks for taking the time. Keep reading for our Q&A module for you to scroll through and follow along, too. Thanks for listening!
Autoblog Podcast #317:

Nissan IDx Nismo and IDx Freeflow concepts are a bridge to the Datsun 510

We're not sure if someone from The Adjustment Bureau stopped by Nissan's PR department to explain the IDx Nismo and IDx Freeflow concepts, but the company's odd press release can't diminish our love for these two show favorites. We had been told to look out for an unnamed Datsun 510 BRE homage, and once we saw the brothers IDx, we knew we'd found them. But the press release doesn't mention anything about the Datsun 510 Brock Racing Enterprises, nor does it mention one Mr. Peter Brock, the man who won two Trans-Am championships in the Seventies for the nascent Japanese budget brand.
Instead, it declares that the cars were the result of a co-creation product development process with "digital natives," said natives being the whippersnappers born after 1990. Nissan says it worked with the young'uns to create two different expressions of "their desire for a basic, authentic configuration for a car." If that's true, it appears that what the kiddies really want are... two different homages to the Datsun 510 BRE that Peter Brock used to win two championships in the seventies for the nascent Japanese brand.
The IDx Freeflow - the "ID" is for "identification," the "x" is "the variable representing the new values and dreams born through communication" - takes the casual approach, with a light khaki exterior hue, a minimalist interior decked out in denim and a console shifter that works a continuously variable transmission. The IDx Nismo is out for blood, from its crimson interior to its five-point harness to its bolt-on flares and sidepipes. We aren't told what the digital natives requested for powerplants, but that's alright; if this is what "co-creation" looks like, we're not entirely against it except where that "CVT" is involved.