PD100 has variable intake manifold...

[Pelican18TQA4]

So now I'm even more curious! Does the ALH head have the separated passages as seen below in the PD100 head?

I can't imagine what purpose this would serve considering there's only one intake valve per cylinder. If there were two intake valves per cylinder I could see how feeding air to only one valve would increase low-end torque and air to both intake valves would increase high-end hp.

This is very perplexing! I want to know why VW has this on the PD100 and how it's utilized!

 

[nicklockard]

This is very perplexing! I want to know why VW has this on the PD100 and how it's utilized!

I think its purpose is to control the form of tumble or swirl that the air takes into the combustion chamber, to improve mixing under a greater range of engine loads and rpm's and minimize NOx and particulates emissions. A statically designed port can only introduce swirl or tumble under certain engine rpm/load combinations (meaning it has less control over emissions in the other regimes.) But, I'm just guessing.

And no, I don't believe the ALH head has these bifurcated intake ports.

 

[PDJetta]

Facinating. The head ports are partitioned too! I can't wait for the riddle to be solved. The internet is sparse on this. I found nothing. We may just have to find the German VW design paper on the BEW engine!

--Nate

 

[JoeBleed]

Ok. it might just be me and my eyes, but i don't see partitions on the head ports? I have looked at it normaly and zoomed in so only one, or in one of the othe rpics, both ports filled the whole screen. Beyond that it just looks like blocks. (pixels)

The partitions are clearly visiable on the intake.

 

[NathanMSL]

Ok. it might just be me and my eyes, but i don't see partitions on the head ports? I have looked at it normaly and zoomed in so only one, or in one of the othe rpics, both ports filled the whole screen. Beyond that it just looks like blocks. (pixels)

The partitions are clearly visiable on the intake.

Try this

 

[JoeBleed]

That helped. Thanks,

I looked at the orginal pictures again now that i am home, And i can see it on my monitor here. The 2 i have at work aparently suck. I didn't even need to zoom in on the orginals posted in the thread.

But that big on you posted is nice.

 

[timmyd]

I have a little bit of intake manifold design experience from my Formula SAE (half sized F1 cars with 600 cc engines)building days back in university.

What is happening with the two intake runners is that the designer is using two different length and diameter runners to feed the intake valves. This is done to utilize pressure waves produced by the velocity of the air the opening and closing of the intake valves. By verying the length, the distance the air travels and the diameter of the runner, the velocity (remember velocity is dependent on flow rate and crossection area) the pressure waves can be altered to hit the intake valves just as they open. All of this is calculated in a very complex equation call the hemiholtz equation.

BMW uses a infinity variable intake (vw is only 2 stage) on their cars, its called VANOS I believe.

 

[JoeBleed]

Any theroys if this would be for emmisions, econemy, or what? and why they PD 150 doesn't have it?

Thanks.

 

[Pelican18TQA4]

Any theroys if this would be for emmisions, econemy, or what? and why they PD 150 doesn't have it?

Thanks.

Does the rest-of-world PD100 even have it??

 

[04PDWagon]

Any theroys if this would be for emmisions, econemy, or what? and why they PD 150 doesn't have it?

Thanks.

I would say it has to do with increases intake air velocity at low RPM as well as swirling as has been mentioned before. Also, where is the injector situated in the head with relation to the port? VW is probably trying to get a more consistent mix and combustion throughout a larger range of conditions.

BUT, it looks to me like it'd just be one more thing to get clogged and gummed up. As I'm closing in on 65K miles i'm thinking that it may be time to remove that manifold and clean it.

 

[JoeBleed]

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?

 

[04PDWagon]

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?

You do have a valid point.

Perhaps to aid in exhaust scavenging when the intake valve first opens? Maybe the smaller port is aimed towards the exhaust valve opening???

EDIT: Another thought...

With increased EGR activity in our PD motors, could this be an attempt to get the EGR gasses to mix better with the fresh air charge prior to compression????

 

[JoeBleed]

With increased EGR activity in our PD motors, could this be an attempt to get the EGR gasses to mix better with the fresh air charge prior to compression????

That does sound good. It would be about the only thing in the intake air track that i can think of that would need mixing. Thinking on those lines, it might would help aid in mixing any oilvaper better. Maybe.

Too bad a VW engineer can't post on the matter.

 

[04PDWagon]

That does sound good. It would be about the only thing in the intake air track that i can think of that would need mixing. Thinking on those lines, it might would help aid in mixing any oilvaper better. Maybe.

Too bad a VW engineer can't post on the matter.

Maybe Jeff R. can shed some light which should be as good or better than ^^^.

 

[SootFoot]

Perhaps we could do some testing with the vacuum actuator unplugged so it leaves the smaller ports blocked, and then some testing with constant vacuum applied to leave the smaller ports completely open??

*PD150 pics are courtesy of RWDdiesel*

I can't add much to this, but I do have this: The vacuum line to the variable intake vacuum actuator (part 17 in the first screenshot of this thread) was a bit pinched on our '05 Beetle TDI, had probably been that way a while. When I corrected it (took the minor pinch out of it) the car ran better with better low end throttle response, mainly when the engine was cold and not yet up to temp. Not real noticeable... but noticeable to my finely tuned SOTP (Seat Of The Pants).

You know how the vac line to the variable intake actuator runs along the air supply duct in parallel with the vac line that goes to the turbo boost actuator? Well, the vac line for the Variable Intake Actuator was not in its c-clamp retainer it was instead poked down in between the two tandem retainer c-clamps which pinched it a bit. Recommend everyone make sure theirs is secured in its retainer c-clamp properly.

The retainer c-clamp is mounted on the plastic intake air supply duct. has two c-clamps that hold the two vac lines in parallel. The one I refer to is the last one the two lines are secured to before they each go their separate ways, one to the turbo boost actuator and one to the variable intake actuator. It is hard to eyeball it you have to go a lot by feel at least on the Beetle.

 

[04PDWagon]

I can't add much to this, but I do have this: The vacuum line to the variable intake vacuum actuator (part 17 in the first screenshot of this thread) was a bit pinched on our '05 Beetle TDI, had probably been that way a while. When I corrected it (took the minor pinch out of it) the car ran better with better low end throttle response, mainly when the engine was cold and not yet up to temp. Not real noticeable... but noticeable to my finely tuned SOTP (Seat Of The Pants).

You know how the vac line to the variable intake actuator runs along the air supply duct in parallel with the vac line that goes to the turbo boost actuator? Well, the vac line for the Variable Intake Actuator was not in its c-clamp retainer it was instead poked down in between the two tandem retainer c-clamps which pinched it a bit. Recommend everyone make sure theirs is secured in its retainer c-clamp properly.

The retainer c-clamp is mounted on the plastic intake air supply duct. has two c-clamps that hold the two vac lines in parallel. The one I refer to is the last one the two lines are secured to before they each go their separate ways, one to the turbo boost actuator and one to the variable intake actuator. It is hard to eyeball it you have to go a lot by feel at least on the Beetle.

Would it be possible to take a picture and point it out?

 

[SootFoot]

Would it be possible to take a picture and point it out?

I can try later today after work, maybe tomorrow depending on tonight's plans...

 

[04PDWagon]

I can try later today after work, maybe tomorrow depending on tonight's plans...

I'd appreciate it...I'm sure others would too!!

 

[david_594]

I have a little bit of intake manifold design experience from my Formula SAE (half sized F1 cars with 600 cc engines)building days back in university.

What is happening with the two intake runners is that the designer is using two different length and diameter runners to feed the intake valves. This is done to utilize pressure waves produced by the velocity of the air the opening and closing of the intake valves. By verying the length, the distance the air travels and the diameter of the runner, the velocity (remember velocity is dependent on flow rate and crossection area) the pressure waves can be altered to hit the intake valves just as they open. All of this is calculated in a very complex equation call the hemiholtz equation.

BMW uses a infinity variable intake (vw is only 2 stage) on their cars, its called VANOS I believe.

Forumla SAE is a blast. I did it my freshman year of college. I made lots of small parts, never really got into the engineering design side of things though.

I agree with you idea and I think its half correct. If you run the numbers for a tdi in light of the fact that we are running fairly high boost and at such low RPMs(relatively) you will find that runners would need to be impractically long.

Ok and here is my theory......

The dual chamber design is done to reduce intake clogging. Under high EGR conditions it can would close off the small port. By doing this it is forcing flow through the reduced area which would increase the velocity of the air. At the higher air velocities less soot buildup would occur. Under high load(and rpm) conditions there is less EGR and it will open the smaller port to allow better flow.

Just my theory. Thoughts? Comments?

 

[mojogoes]

Could the smaller port be there to introduce the egr air/fumes into the intake at a higher velocity/rate than it would be , so not to disrupt the main/larger intake velocity/port at low rpm's when egr would be in operation...just an idea which may have been mentioned already.

If its found that other than this pd 100 engine or any others which you have (pond) only has the twin ports etc....you can bet your bottom dollar it will be for emission control and not at all for performance.

 

[SootFoot]

Here are some pics of what I was referring to above. On our Beetle, the vac line to the Variable Intake Actuator (part #17 in first post of the thread) was pinched in the middle retainer. The pic is the best view of it I have had, and I now think the vac line simply wasn't shoved down all the way and was pinched by the top end of the retainer, because from the pic all three retainers look the same dimensions. I didn't see until this pic that its an actual three retainer unit not a tandem unit with only a notch in the middle as I had said above.

 

[mojogoes]

Those links don't work for me.

 

[SootFoot]

Those links don't work for me.

I think I have the links fixed now.

 

[JoeBleed]

Thanks for the pic. It is a good one. i will try and check mine out tommorow. Would have done it today but not only did i over sleep till 1:30 but i had some other things that really need to get done. Hopefully the weather will permit for some exploring tommorow. It was a nice clear day today. would have been great tinkering light.

 

[TDIMAXIMA]

Guys this is a great thread. Its teh first time anyone has confirmed that the intake can be controled from something other then the boost and egr throttle plate. My question is this. If the lower variable intake actuator were to fail or not function properly, is it safe to say there would be power loss? When I have the intake out for cleaning, what would be the best way to test it?

 

[milehighassassin]

Very interesting thread!

 

[Pelican18TQA4]

I was enlightened on the specific function of the variable manifold on the PD100 versus the non-variable one on the ALH. The ALH has bumps, for lack of a better word, in the intake ports that cause the intake air to swirl as it enters the cylinder. This helps clean up smoke at lower RPM due to more complete combustion of the fuel which also benefits economy and power. The downside is that the bump in the intake ports inhibits airflow at higher RPM because the bumps are in the way of the fast moving air.

Move to the PD100. It has no bumps in the intake ports. Instead, the ports are divided into two unequally-sized chambers. Matching the divided intake ports is the variable portion of the intake manifold. At lower RPM, the smaller ports are blocked off to promote swirl. As engine RPM increases, the smaller ports open allowing a higher volume of air to enter the cylinder thereby giving the engine more mid-range and high RPM power. This also explains why the PD100 carries torque over a broader RPM than the ALH and why it pulls harder at higher RPM.

Thoughts?

 

[PDJetta]

I read recently that the variable intake manifold helps increase the exhaust gas flow under pressure into the intake manifold, I think. My guess is that ist strictly emissions reduction related.

--Nate

 

[Rub87]

I was enlightened on the specific function of the variable manifold on the PD100 versus the non-variable one on the ALH. The ALH has bumps, for lack of a better word, in the intake ports that cause the intake air to swirl as it enters the cylinder. This helps clean up smoke at lower RPM due to more complete combustion of the fuel which also benefits economy and power. The downside is that the bump in the intake ports inhibits airflow at higher RPM because the bumps are in the way of the fast moving air.

Move to the PD100. It has no bumps in the intake ports. Instead, the ports are divided into two unequally-sized chambers. Matching the divided intake ports is the variable portion of the intake manifold. At lower RPM, the smaller ports are blocked off to promote swirl. As engine RPM increases, the smaller ports open allowing a higher volume of air to enter the cylinder thereby giving the engine more mid-range and high RPM power. This also explains why the PD100 carries torque over a broader RPM than the ALH and why it pulls harder at higher RPM.

Thoughts?

What bumps do you mean? he swirl part? I polished my AFN head ant didn't notice any bumps..? Only the fustration swirl part with sucks ass to polish..

 

[Pelican18TQA4]

Is the AFN head the same as the ALH?