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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: the reason you have not seen this
By lagomorpha on 9/6/2011 6:16:22 PM , Rating: 2
You're comparing constant pressure engines to constant volume engines.

In a diesel engine, the air intake is left fully open and the throttle controls how much fuel is injected into the cylinder. Press on the gas pedal = more fuel.

In a gasoline engine, the gas pedal controls a butterfly valve in the intake which lets more air in then either a carb or fuel injection will do its best to keep to the designed air-fuel ratio. (14.7:1 stoichiometric though modern EFI will run leaner under certain conditions for emissions reasons and old British motorcycles ran rich to aid with cooling and no one cared that they got bad gas mileage).

It isn't a matter of the computer leaning out the diesel when it's idling, the throttle position directly means less fuel is being injected.

RE: the reason you have not seen this
By haplo602 on 9/7/2011 2:41:59 AM , Rating: 2
modern cars have without exception electronic gas pedals. means the computer ALWAYS controls how much fuel is injected.

By mindless1 on 9/8/2011 11:49:52 PM , Rating: 2
They don't have to be so modern either, nor have electronic gas pedals. When the first, maybe 2nd generation of fuel injected vehicles arrived over 20 years ago, you still had a throttle cable from the gas pedal but it went to a throttle plate which just opened more to let more air in, then the mass airflow and temperature sensors fed the ECM (computer) this data upon which it determined fuel injection time = rate/volume.

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