PD100 has variable intake manifold...

Rub87

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No, it's the older style, with the water exit facing front.. but ports should be the same I think..
 

04PDWagon

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TDI Dieseldude said:
Can anyone confirm whats with this manifold??
I'll be doing my timing belt and intake cleaning next month...I'll post up what I find on my PD...should be the variable intake.
 

PDJetta

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I think the variable intake manifold is used to induct greater exhaust flow into the engine, for the EGR system. The European TDI PDs do not use this variable intake. There NOx regulations are more lax.

--Nate
 

Rub87

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I think they put it on because otherwise the engine would have more than 100bhp ;-P
 

TDI Dieseldude

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Are you sure about inducing egr flow stuff? The amont of cash it would cost vw to install this would be way more than just designing the egr valve to stay open a little longer. I could be wrong though! Someone mentioned earlier the cars equiped with this manifold make better curves. If this is the case whats different between the types of engines that will give that result? I dont think more egr gas will do that!
 

TDI Dieseldude

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JoeBleed said:
Ok. i am not very briliant when it comes to thinking about fuel mixture. I under stand swurl in a gas vehical that mixs fule in the air before the cylender and why they do it.

But i don't understand it's purpouse in a direct injected engien. gas or diesel. (mostly diesel) The air is injected and then compresed, then fuel is injected. With the valves closed and the piston compressing, i just don't see how intake port configuration would matter one bit for the combustion proccess in a direct injected vehical. The only thing i can think of that would matter in the combustion stage on these vehicels would be injector presure, injector spray patteren and piston top design.

What does everyone else think?
Im no expert but from what i can come up with in my head is just because the valve closes doesnt mean the air that was introduced in the chamber stops moving (swirling). If it still has alot of movement when the diesel is injected when valves are closed, i would asume youl get a greater mix. Even though our motors "only" spin slowly just imagine at even 1000rpm how quick things happen, no chance for swirl to stop if indeed it is created.

Thoughts???
 

JoeBleed

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At the PSI the diesel is injected i don't see how any air swirl would effect it. Though i defenatly could be wrong. And the diesel, as i understand it, starts to ignite just about as soon as it is injected into the high compresed air/space.
 

TDI Dieseldude

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At the PSI the diesel is injected i don't see how any air swirl would effect it. Though i defenatly could be wrong. And the diesel, as i understand it, starts to ignite just about as soon as it is injected into the high compresed air/space.

True but then why design those cups on the piston tops? They are there for swirl, mix and a bunch on other funky stuff correct? Diesel burns slow so again im assuming its important for all the fuel injected is burnt and not wasted out the exhaust due to missing the ignition cycle.

Is there any experts out there??
 

JoeBleed

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good question about the pistons, but i was thinking, i don't know, that that was prety much the compustion space. seeing as the head gasket thicknetss is bassed on piston protrusion and not just a standard size. but this is just my speculation. I have never had the head off of a direct injection motor. seen a couple from IDIs.
 

TDI Dieseldude

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The shape of the cuped combustion space is what im thinking. It looks to me that when diesel is injected it hits centre of piston and swirls back up by the cup shape creating swirl and even mix.

The link below is i know of a gasser but it may have simular physics involved even if the injection timing is way different between the 2.

http://images.google.com.au/imgres?imgurl=http://images.worldcarfans.com/articles/2004/7/15/2040715.002/2040715.002.1M.jpg&imgrefurl=http://www.worldcarfans.com/2040715.002/new-opel-1.2-liter-twinport-engine-premieres-in-corsa-and-agila&h=375&w=500&sz=38&hl=en&start=65&um=1&tbnid=mLIFFTb65rxM4M:&tbnh=98&tbnw=130&prev=/images%3Fq%3Dvw%2Bvariable%2Bintake%26start%3D54%26ndsp%3D18%26svnum%3D10%26um%3D1%26hl%3Den%26rls%3DGGLD,GGLD:2004-09,GGLD:en%26sa%3DN

Comments??
 

nicklockard

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Yes, search for posts on this topic by TdiMeister. He is a power train engineer currently in school for a Master's degree in automotive engineering in Germany.

It's called a re-entrant combustion bowl. IIRC, the swirl is like a helix contained within a toroidal shape (defined by bowl shape.) So, I guess that makes it some combination of tumble and swirl actually. It took VW some time on a supercomputer to come up with the right shape. I was surprised at how far the lip projects out when I held/touched it on a piston.
 

Rub87

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I think that fuel atomisation in the closed-of runner will not do very well..
 

jsrmonster

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Rub87 said:
I think that fuel atomisation in the closed-of runner will not do very well..
Correct for your lawnmower, however . . . no fuel in the intake, it's gets injected downstream into the cylinder . . . only air flows thru the small ports. . . think direct injection, not normally aspirated gas :)

engineers restrict the air intake during low load to increase flow velocity. I suspect it helps reduce clogging if stuff is moving by faster, but restricting intake is not emissions beneficial, imho. It makes the boost gages dance around funny when intake velocity/volume is constantly changing. I just unplug the dashpot so it defaults to open position all the time. It compliments egr0 for offroad apps. ;-)
 

Rub87

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Not in the twinport drawing..

The 16v 2l tdi has such a flapper in the intake..
 

TDI Dieseldude

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jsrmonster said:
Correct for your lawnmower, however . . . no fuel in the intake, it's gets injected downstream into the cylinder . . . only air flows thru the small ports. . . think direct injection, not normally aspirated gas :)

engineers restrict the air intake during low load to increase flow velocity. I suspect it helps reduce clogging if stuff is moving by faster, but restricting intake is not emissions beneficial, imho. It makes the boost gages dance around funny when intake velocity/volume is constantly changing. I just unplug the dashpot so it defaults to open position all the time. It compliments egr0 for offroad apps. ;-)

One thing im not sure about is isnt the default setting of egr cycle to be off at low rpm and high rpm but be cycling gasses at cruising speeds? If they were increasing velocity at low rpm with egr being off what would be clogging if at low rpm the egr valve is closed????

Someone should make friends with a vw tech dude so we can work out whats goen on because i have no idea what im talking about.

Cheers
 

Lucas

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The butterfly valve, shown in the photo below. Does it function as a shutter valve or something more...?

If it is just a shutter valve, I'd like to try to build on my ASV.

 

Rub87

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If it is just a shutter valve, I'd like to try to build on my ASV
ASV has anti shudder valve by default.. it's vacuum controlled.. It only serves to freeze the engine faster after you put it off, or when you get a runaway caused by too much oil in the intake system (turbo failure)
 

Lucas

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Rub87 said:
ASV has anti shudder valve by default.. it's vacuum controlled.. It only serves to freeze the engine faster after you put it off, or when you get a runaway caused by too much oil in the intake system (turbo failure)
I know that. I was asking for the function of the butterfly valve in the picture.

This system also has a valve in the 'block' where the EGR-cooler attaches to. I'd like to know what the exact functions are for both valves. Do they both act as a anti-shudder valve for instance...?
 

Rub87

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one is the egr valve, and on is the anti shudder valve.. there are no other valves in a asv intake manifold..
 

PDJetta

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Lucas said:
I know that. I was asking for the function of the butterfly valve in the picture.

This system also has a valve in the 'block' where the EGR-cooler attaches to. I'd like to know what the exact functions are for both valves. Do they both act as a anti-shudder valve for instance...?
The throttle plate (pictured above) serves three purposes:

1. Quiet engine shutdown (limits air induction into the cylinders to lower the compression pulses).
2. Protection in case of a lube oil fueled engine runaway (usually from a turbo failure) by cutting off the air entering the engine.
3. To increase EGR flow rates. The throttle plate works in conjunction with the EGR valve to increase the exhaust gas flow into the intake manifold up to 50% of the intake charge on light load operation. The plate closes some as the EGR valve opens, thus creating a vacuum in the intake manifold. Exhaust gas, more than would flow without the throttle, now flows through the EGR valve, thus lowering the intake manifold vacuum (bleeds off the vacuum). The 02 sensor works with the ECU to provide feedback on NOx content (calculated via O2 content) to trim the operation of the EGR valve and throttle plate for precise NOx control.

The other flap, on the EGR cooler mounting flange, is an EGR cooler bypass valve (vacuum operated). When the engine is cold, uncooled exhaust gas goes into the engine (the cooler is bypassed). VW claims this lowers engine warm up time. At a certain engine coolant temperature, the bypass valve actuates and exhaust gasses are now routed through the exhaust gas cooler, to lower NOx more than would occur without the cooler, since hot exhaust will not cool combustion temperatures as well as cooler exhaust gasses.

--Nate
 
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Lucas

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@Rub87: I think you don't understand ;). I'm talking about the engine in the pic (or in general AXR or BEW engines), not the ASV.

@PDJetta: Thnx!

Does anyone know how this anti-shudder valve (No 9) can be operated? I'd like to build one on my VP engine. It has 4 connections. Two of them are plus and ground (1 & 2), the other two are signal wires (3 & 4). I guess it is some kind of bipolar stepper motor. I tried putting 12V on pins 3 and 4 but that doesn't work. All info is welcome!

 
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PDJetta

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Lucas said:
@Rub87: I think you don't understand ;). I'm talking about the engine in the pic (or in general AXR or BEW engines), not the ASV.

@PDJetta: Thnx!

Does anyone know how this anti-shudder valve (No 9) can be operated? I'd like to build one on my VP engine. It has 4 connections. Two of them are plus and ground (1 & 2), the other two are signal wires (3 & 4). I guess it is some kind of bipolar stepper motor. I tried putting 12V on pins 3 and 4 but that doesn't work. All info is welcome!

Here, see this:

http://www.kspg-ag.de/pdfdoc/kspg_produktbroschueren/p_drosselklappe_e.pdf

Pierburg makes the throttle plate. Here is their literature on it. See Figure 3 for the wiring.

--Nate
 

TDI Dieseldude

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Below is an email I recieved from pierburg with regards to my question about the little flappy things in each runner.

Dear Julian,
there are two possibilities:
1) Variable intake length of the manifold
I assume in yr. case you might have this kind of variable intake manifold,
i.e.
there are 2 switchable lengths of the intake manifold: a long one and a
short one.
"Long" is very good for part load condition to improve torque and
efficiency -
and "Short" is good for maximum power at top engine speed.

2) Swirl flaps
these so called "SWIRL FLAPS" in front of the ports of the cylinder head
are used to enable an optimized flow of the intake air just very near to
the intake valves.
Under partial load condition one flap is closed and at full load both
flaps are open.
Car manufacturers / engine builders are optimizing with this measure
the performance of the engine especially under partial load condition.
This improves the exhaust emissions reduction.

Best regards
MS Motor Service International GmbH
Helmut Steckel
Produktmanager

So what do people think??
 

david_594

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They sound and look like the swirl flaps he describes. They change the velocity of the incoming air into the cylinder head.
 

PDJetta

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I agree. I've always thought this was done to pass emissions regs. This"variable intake manifold" is not on European PDs.

--Nate
 
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