Dynamic Cylinder Deactivation

[euromodder]

The first commercial DCD-application in small-displacement passenger cars is a reality as the VW Polo Blue GT hits the market.

2012 Volkswagen Polo Blue GT mixes fun and frugality

Only 4 cylinders, 1.4L in all, but it shuts off the 2 inner cylinders between 1250 and 4000 rpm in conditions where it only has to deliver between 25 and 100 Nm of torque .
That condition occurs for 70% of the NEDC - and in just about all cruising conditions - so fuel consumption is low(ered).
The switchover between 2 and 4 cylinders occurs in 13 to 36 ms, depending on rpm.

It's no lead slug either with 140 HP, and 7.9 s to 62.5mph

[shovel]

That sounds pretty excellent, euromodder - clearly if this becomes more prevalent in OEM applications, the idea of trying to emulate it in aftermarket will have a very predictable arc of relevancy.

[Heihetech]

"The first commercial DCD-application in small-displacement passenger cars is a reality as the VW Polo Blue GT hits the market."

No! Something you have posted belongs to 30+ years old traditional cylinder
deactivation, nothing new, just the VW product is new. How much would you
expect to pay for such outdated technology? You must pay some $16,000, or
$2000 to trade-in your used car to get it, not cheap. For each 4-cylinder
DCD CONTROLLER KIT, it only cost you $500, and will be paid back sooner.

Technically, it's 50% deactivation is the number that always trend to over-
deactivation, making engine power too weak to do regular driving. So it has
less chance to be turned on, not always useful. Does it deactivate 25%???
NO! But DCD can, so as to best match the engine power to the driving need,
and can be turned on most of time for maximum fuel savings. Utilization
is always a big issue for these energy saving devices.

Does it deactivate every cylinder alternatively??? NO! It only shut down 2
fixed inner cylinders, making them over cooled and suffering abnormal wear.
DCD controls vary from cycle to cycle, while mechanical control can not
act very fast. Or it would wear out soon. Yet electronics based DCD lasts
almost forever, at lease the life time of vehicle.

So you may conclude which one is better, and who will beat who??? If DCD
could not beat such outdated technology, why spend big effort to develop it?

[Ecky]

Originally Posted by Heihetech

Stuff

Keeping the valves closed will result in lots more savings than just alternating injectors.

[Heihetech]

Originally Posted by Ecky

Keeping the valves closed will result in lots more savings than just alternating injectors.

Just a little bit more benefits, like reduced pumping loss and save the energy
to drive the valves. But these benefits comes from higher cost and sophistication.
All in all, 50% fixed deactivation is a killing factor, a technology dead zone.
You may try to unplug 2 injector wires to get the driving feeling, then you are
killing the driving ability.

[jakobnev]

Heihetech -

Which part of "The switchover between 2 and 4 cylinders occurs in 13 to 36 ms, depending on rpm." did you not understand?

[t vago]

Originally Posted by Heihetech

Just a little bit more benefits, like reduced pumping loss and save the energy
to drive the valves. But these benefits comes from higher cost and sophistication.

So, now we've heard this directly from you.

Can somebody explain why, if your approach to cylinder deactivation is oh-so-much better than "30+ year old traditional cylinder deactivation" technology, then why haven't the major auto manufacturers done something like your firmware-only approach?

And can somebody explain how an OBD-II controlled engine will not throw a misfire code from deliberately causing a cylinder to not fire during the engine's run cycle, such as from installing your wonder gadget? Or for causing successive cylinders to not fire in turn at each revolution of the crank?

Or how an OBD-II controlled engine will not throw an injector circuit broken code from deliberately removing an injector coil out of the engine computer's driver circuit?

Or how your wonder gadget somehow prevents the OBD-II computer from throwing some other code related to catalytic converter efficiency monitoring?

Sorry, but you're going to have to do better than wow us with shoddy press releases and your own personal testimony. Oh, and do try to actually answer the questions without going into hysterics.

[Heihetech]

Originally Posted by jakobnev

Heihetech -

Which part of "The switchover between 2 and 4 cylinders occurs in 13 to 36 ms, depending on rpm." did you not understand?

The answer is "Quick Switchover Does NOT Mean Dynamically Cycle by Cycle".
Narrow minded, you just understand the first point, not the second and so on.
There are many requirement to run TRUE DCD Dynamically Cycle by Cycle, only
has fast switchover time is not enough. Are you trying to wear it our very soon?
to run TRUE DCD Dynamically Cycle by Cycle, you need to disable all 4 cylinders
instead of the inner 2. The deactivation should be done one by one, not 2 at
the same time. Please don't be fooled by the old technology packed in a new
product!

[Heihetech]

Kitteh head, you always sounds awful that no one is willing to hear from you!
Please get out of DCD THREAD that introduces nice affordable fuel saving
technology. Even you don't like, hate, don't understand it, DCD skill works in its
way, not the way you imagine. DCD is always effective even you feel not.

Those questions should go to ask the car manufacturer themselves. I
just want to tell you that they are NOT licensed to use DCD patent yet. The
patent means I have but others include you don't have. Wish you will not so
jealous to it.

[shovel]

OK after reading a little more about this DCD system, I think I understand a little more about why it could be somewhat efficient...

Since English is apparently Heihetech's second language (I am guessing?) the way he uses words is a little different than what most of us are used to, but since I only speak one language I can't fault him for these differences.

If I am understanding this correctly, these are the 2 things going on:

• First it's simply interrupting the signal to each injector in a random pattern, based on load or throttle position or whatever data source it uses. The reduction in fuel consumption "at face value" seems self explanatory there, if it doesn't introduce a pumping inefficiency.
• Second, because the cooler air drawn into each (momentarily inactive) cylinder during the intake cycle is heated both by compression and by the neighboring active cylinders, it acts as a weak stirling engine so although there are pumping losses from drawing air in and out past the valves, the net energy lost into inactive cylinders is potentially less than you'd expect

So, up to a certain point if you randomly disable injectors, say, 20% and then alter the o2 sensor feedback by the same 20%, and you lose 10% net efficiency into pumping air past the valves on dead cylinders, you still end up with a net 10% less fuel entering the engine - and because you're drawing work out of waste heat this also slightly relieves your cooling system because less fuel burned always means less gross heat generated (these numbers are just arbitrary examples for the purpose of discussion)



Am I understanding this correctly? Or am I way off?