VW quantifies MPG gain of 4- to 2-cylinder deactivation at 31 mph = +16 mpg

[Ken Fry]

Originally Posted by some_other_dave

Y
Honda has done the V6 single-bank deactivation. Several manufacturers have deactivated various parts of V8 motors, with varying levels of success.

-soD

The current Honda deactivates a single bank for 3 cylinder operation, and deactivates one cylinder from each bank for four cylinder operation.

[Xist]

some_other_dave, do you see room for improvement?

What about the world's smallest V16?

[UFO]

Originally Posted by hancock

Thanks Ken for your reassurence!

However with any new technology there has to be 'due diligence' by that I mean not only engine test bed testing to build up sufficent technical confidence on the application and on the actual wear parameters since there will be 'sliding' wear.

The valve operating mechanism in any 4 stroke engine is where special attention has to be made to protest 'sliding' surfaces. For instance the introduction of roller followers on cams.

So no hydrodynamic protection and wear protection will be based on the lubricant antiwear properties (ZDDP) and metalurgical considerations such as choice of material and surface treatment to the splines that move the 'collar mechanism' also how this movement interacts with the cams surfaces?

Additionally, I'm sure VW would have conducted field trails to assess wear in the real world. All this testing takes time to complete before the engine can obtain VW sign off and approval.

So I belive in this case where VW is introducing new technology, there needs to be warranty protection.

Absolutely right, especially with VW. As far as I'm concerned, VW needs extra scrutiny due to their massive failure on the new common rail diesels. 2009 and 2010 diesels have a very common injection pump failure, and though they have finally seemed to address the problem, they were prone to blaming the new owners on putting gasoline in the fuel and dragging out the warranty process to a ridiculous degree before honoring warranty coverage.

[slurp812]

Just got my G/F the 3.9l GM engine in a 2008 Impala with active fuel management. AKA cylinder deactivation. So far so good. when driven gingerly, I can get some pretty good numbers on the built in MPG gauge. Of course she drive with her foot in it more than I would. With lots of highway driving she has the average mileage just over 25 mpg. Not bad for a boat of that size...

[thomason2wheels]

Originally Posted by UFO

Absolutely right, especially with VW. As far as I'm concerned, VW needs extra scrutiny due to their massive failure on the new common rail diesels. 2009 and 2010 diesels have a very common injection pump failure, and though they have finally seemed to address the problem, they were prone to blaming the new owners on putting gasoline in the fuel and dragging out the warranty process to a ridiculous degree before honoring warranty coverage.

Others may disagree, but in my experience, all car/bike companies tend to stick their corporate heads in the sand (or up their donkeys :-D) when confronted with quality issues until enough people take them to task and hold them responsible. I can think of numerous examples of this. This is not unexpected and is largely reasonable. They want enough proof of their transgressions before going thru the expense and hassle of accepting blame and making good on their mistakes. Of course there are well documented cases where the company, even after years of evidence pointing to a need for action on an issue remains unmotivated to correct the problem....case iin point, suzuki has known for years about lean running roughness on their dl1000 engines and to my knowledge has done nothing to fix it.

[some_other_dave]

Originally Posted by Xist

What about the world's smallest V16?

I'd say it was really cool, but the internal friction would be pretty high.

-soD

[NeilBlanchard]

VW wins "Best New Engine Award" for 1.4L TSI:

Green Car Congress: VW wins

[pete c]

Nice video.

My first thought was that there will be issues with getting that thing to slide along the spline that quickly and what about the follower falling off/smashing into the edge of the cam during transition. After looking at it a while, I realize that this can't happen and that the transition happens while off cam.

So, maybe it can fly. You would definitely want to stay on top of your oil changes though.

Any chance of seeing this in the 2 liter golf engine?

I would think that they could get close to tdi highway numbers. Likely beat them when looked at from a $pg vs mpg viewpoint.

Does anyone have any figures on what sort of load the 2 dead cylinders are? The reason I ask is how much more of a gain could be realized in an engine that completely stopped the dead cylinders?

How tough would it be to make a clutch that would lock into place only when the 2 halves of the crank were back into perfect phase? And can you even do an I4 where the front and back two work as independent units? The VW uses the inner/outter cylinders together.

[euromodder]

Next step : combine the various technologies that are found on different VWs ...

Like cylinder deactivation + CNG + exhaust manifold integrated in cylinder head (quick warm-up) + DSG-7 with coasting option + ...

Does anyone have any figures on what sort of load the 2 dead cylinders are? The reason I ask is how much more of a gain could be realized in an engine that completely stopped the dead cylinders?

Decoupling the valvetrain is one thing - decoupling 2 cylinders from the crankshaft is something else entirely.

What's a starter engine on a small displacement engine ?
1 to 2 kW ?
That's enough to get the engine going against its compression - a load the deactivation mechanism avoids.

[pete c]

My question was how much of a load the deactivated pistons are. I realize the airspring idea means they are a small load, but, they are a load, none the less.