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

[MetroMPG]

Found a YouTube video - (I embedded it in the first post of this thread) - of VW's mechanical approach for deactivation. As suspected, it's done via closing all the valves on the cylinder.

Or, direct YT link: Volkswagen cylinder deactivation technology on 4-cylinder engine introduced - YouTube

[MetroMPG]

And... also found VW's press release with technical details. I added it to post one as well.

[Ken Fry]

Originally Posted by WD40

IMHO it would be more effective to disable the appropriate injector and leave the valves alone, it seems to me that by shutting both intake and exhaust valves the piston would essentially be creating a vacuum causing even more issues.

An experiment you can do: Run your vacuum cleaner. Put your hand over the end of the hose. The motor speeds up, meaning the the motor is working less. (You can verify this with a watt meter.)

Closing the valves lets the cylinder function as an air spring.

[Ken Fry]

Originally Posted by Frank Lee

Nice, but perhaps I won't be pulling those two pistons after all. :/

Honda has a system under development in which nanotech robots actually dissemble and reassemble the engine, placing the unused pistons and rods on a nicely padded shelf, temporarily. They have demonstrated process times down to 5 milliseconds -- fast enough for any road-going engine. The engine is automatically declutched from the driveline during the rebuild process: 1. Declutch 2. Engine stop. 3. Engine dissassembly/reassembly 4. Engine start, 5. Clutch re-engagement.

Although this works fine in the lab, they have been unable to find a place to put the parts shelf in a production car, what with the engine compartment being so congested.

It is believed that future implementations will include the option to re-ring the engine at high mileages.

[drmiller100]

Originally Posted by Ken Fry

An experiment you can do: Run your vacuum cleaner. Put your hand over the end of the hose. The motor speeds up, meaning the the motor is working less. (You can verify this with a watt meter.)

Closing the valves lets the cylinder function as an air spring.

actually with no air the fan cavitates out.

a better experiment. run your vacuum with an amp meter on the cord.

then plug the inlet until you see 5 mm of vacuum. then read the amp meter.

[hancock]

Interesting VW ACT technology, however, what about engine vibration frequencies with only two cylinders activated?

Also the engine big end bearings are designed to carry bearing loads for four cylinders so will what about wear on big end shell life on the cylinders 1 and 4 during deactivation?

The wear life of the deactivation mechanism? How many times in the average journey will it operate?

VW will have to re-assure buyers of the Polo Blue GT 1.4 L engine live or give a special warrantee?

[ecomodded]

with the appropriate 2 cylinders deactivated at the same time the vibration would not be an issue.

The bearings will last longer with less hp wear as it would be traveling gently a great deal of the time.

vw name is so good they have it made and will not have too assure anybody of anything, unlike some other car companies.
I like it !

[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.

[Frank Lee]

Worry about nothing much?

[jmcc]

I expect that VW will have done massive testing mileages and thousands of hours on the dyno before going to production. I imagine this has been under development for years and personally I wouldn't have many qualms about buying one.