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VW 1.4L TSI
VW engine will be the first 4-cylinder in the industry to use cylinder deactivation tech

With more stringent fuel economy standards looming in the U.S. and elsewhere, auto manufacturers are looking to pull out all the stops to improve economy as much as possible. Carmakers are turning to technology like direct injection and automatic start/stop. Several automakers are also using cylinder deactivation on their larger engines.

Cylinder deactivation is something that some carmakers in the U.S. and abroad have used for years. Chrysler has used the technology in its Hemi engines, Honda uses it on some of its V6 models, and Audi will use cylinder deactivation in its new line of “S” performance models.

VW is set to make a first in the automotive market by offering cylinder deactivation on its 4-cylinder models.

The VW tech will turn off two engine cylinders under certain conditions. The engine is called the 1.4L TSI and VW promises that it will offer a fuel savings of 0.4-liters/100km and when combined with start/stop technology the vehicle would save 0.6-liters of fuel. For those more familiar with U.S. mpg ratings, that works out to an improvement of in the range of 
3 to 4.5 mpg on average. 

The engine would turn off two of the cylinders under low to medium loads, and VW says that the tech will meet the future European EU6 emissions standards. The cylinders will be deactivated when the engine is operating between 1,400 and 4,000 rpm and the engine torque is in the range of 25 to 75Nm.

VW claims that operating range applies to about 70 percent of the driving distance in the EU fuel economy driving cycle. VW also points out that as soon as the driver presses the pedal the cylinders will reactivate without the driver being able to tell it happened. The cylinders also would not turn off if the vehicle were being driven in a sporty manner apparently. 



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RE: Good on paper..
By StevoLincolnite on 9/7/2011 6:16:34 AM , Rating: 3
quote:
The engine will run on 2 cylinders ONLY if between 1,400 and 4,000rpm AND the load conditions are satisfied. If you're trying to accelerate then the engine will use all 4 cylinders even if under 4,000rpm. There isn't just a sudden power surge at 4,000 when the other two cylinders come online.


It almost reminds me of power gating on a CPU. Shut off the extra cores when not needed to conserve power.

IMHO if it's seamless and not noticeable by users, then it should be in every car.


RE: Good on paper..
By lagomorpha on 9/7/2011 6:06:43 PM , Rating: 2
More or less, it's a little more complicated in engines.

When you deactivate cylinders in an engine, the deactivated pistons continue to move up and down in their cylinders because there's no realistic way to segment the crankshaft. Because the pistons continue to move, air continues to be pumped in and out of the cylinder. Some of the cylinder deactivation schemes close all the vales to deactivated cylinders so that they expend less energy (like operating a spring; along half the travel you get most of the energy back).

So you aren't completely shutting down the cylinders, but where you do gain efficiency is because the remaining cylinders are run on higher load. Brake specific fuel consumption is lowest at highest load at lower rpm. This means a less powerful engine will generally use less fuel per work done than a larger engine at lower load... sometimes.


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