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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: Good on paper..
By Calin on 9/7/2011 3:12:35 AM , Rating: 2
Look at the fuel economy for a car with smaller-to-larger engines. As the engine size increases, so does the fuel consumption.
If you drive carefully, you can get just a little bit worse mileage with a bigger engine, and have excess power when needed (passing at highway speeds, or maybe city driving accelerating away from a previously unseen danger, or rushing your way from a yield, or something).
So, underpowered cars don't suffer from mileage hits, but suffer from performance issues. Ideal would be a small engine and the capacity for quite large power surges, even if small in duration (50 HP sustained, with surges of 120+HP for 10 seconds or so). That would give you enough sprinting capacity to pass at highway speeds.
This VW engine gives instead the 40-50 or so HP in two cylinders mode and anything from some 80 to 100 HP in four cylinders mode.

RE: Good on paper..
By 0ldman on 9/7/2011 11:47:51 AM , Rating: 2
Obviously you've never owned an underpowered car. 1974 Mercury Comet with a weak 200. Pathetic power, poor mileage...

Older models did well, this one did not.

RE: Good on paper..
By Spuke on 9/7/11, Rating: -1
RE: Good on paper..
By Dorkyman on 9/7/2011 12:26:46 PM , Rating: 3
You miss the point.

A powerful engine at part throttle (high manifold vacuum) is a giant vacuum pump and very inefficient. What these designs try to do is to instantly reduce engine size so the throttle is more open, reducing manifold vacuum and increasing efficiency. Whether this switchover can be done in a way transparent to the driver is the big question, in my view.

RE: Good on paper..
By Spuke on 9/7/2011 1:02:58 PM , Rating: 2
Since this is already being done in other cars, a simple test drive should answer this question. BTW, the poster that I responded to did not mention pumping losses in his post so there was no reason for me to assume he had a clue as to what he was talking about. I didn't miss a thing. If anything, I brought a better explanation out with your post.

That said, I think you mean large displacement engine not powerful engine?? How are pumping losses greater with more hp as opposed to more displacement. I could see displacement being a factor but power? Also, how does this effect fuel efficiency? Ford's V6 gets 29 mpg, my "old" 04 Sentra 2.5L got 27 mpg (both EPA hwy 6 speed manuals). Since the Ford V6 has "more power" and hence more pumping losses, shouldn't it's fuel efficiency be worse than my old Sentra?

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