[DWR]

Originally Posted by tuikku

.
I almost agree.
Theory and practice are not now exactly the same.

Since theory is informed almost universally by experiment, "paractice", I complete agree. However, we aren't disagreeing on practice. I am clearly challenging your theory, in which you say swirl is the main thing. That is not true in practice. There is too much data from around the world the says airflow is the main driver. Swirl is more important in a diesel because of the properties of the fuel.

Originally Posted by tuikku

The first port do the swirl mainly - yes, but that is not the whole thing.
Swirl collapses, when air flow speed become too high.

Yes, of course. Aren't you just theorizing that the airflow is becoming turbulent, or do you have proof/data? I have no measurement, data, experience to support your claim. You maybe right, I do not know. I do know, if you keep the 2nd port closed, you will loose @ 10% HP in the upper rpms. If you measure the airflow, you will see it reduces similarly.

Originally Posted by tuikku

.
The second port has two as important jobs, more air and keep the swirl alive by reducing total air flow speed.

4 valve cylinder heads are well known to have poor swirl. Two valve heads are well known to have more swirl. Of course, there are exceptions for specific cases. Please share your data on swirl for the 335d heads.

Originally Posted by tuikku

.
It is very very easy to spoil the head by porting it so that airflow is great but do not work, at all, smaller amount of air with good mixing gives better result.

TDIwyse was not talking about head porting, when this disagreement came about.
Still, I understand your point. It is well known that mixture quality is very important.

Really enjoying the discussion. Hope you do not find a challenge to your statements offensive. Just trying to have a good discussion and learn. Some of us are not interested in a cookbook of what works in a 335d, we want to understand the principals - the same thing you have said many times.

[tuikku]

.
No
I have written in forums like this over ten years.
This is the first time that anyone who disagrees with me and is able to justify his views and can be right in real life.

Thank you.

... But this do not mean, that I agree with you.
We are not even near the level, when any kind of porting is necessary.
Except valve springs, they are very loose in MB, but even worst in BMW.
Stiffer springs increases fresh air in cyl.
Back pressure get valves floating after ~3,2bar (47psi)

Lower compression reduce cylinder working pressure but do not help heat stress.

[Charged]

I have heard soon there will be more 535d:s which are near or over 500hp.

[tuikku]

Originally Posted by Charged

I have heard soon there will be more 535d:s which are near or over 500hp.

There will be a lot of them.
Swap is so easy.

[335dsleeper]

Originally Posted by tuikku

.
No
I have written in forums like this over ten years.
This is the first time that anyone who disagrees with me and is able to justify his views and can be right in real life.

Thank you.

... But this do not mean, that I agree with you.
We are not even near the level, when any kind of porting is necessary.
Except valve springs, they are very loose in MB, but even worst in BMW.
Stiffer springs increases fresh air in cyl.
Back pressure get valves floating after ~3,2bar (47psi)

Lower compression reduce cylinder working pressure but do not help heat stress.

So what valve springs?

You're saying porting and cleaning up isn't worth it, I tend to agree as the power levels we're at may not "need" it, that said, in the US when someone says "port the head" it usually suggest the entire head is getting gone through. i.e. cleaning the ports, blending bowls, valve job and ensuring springs/seals and retainers are functioning as designed and up tot he task. I'll have my head done eventually and I will focus on the valve job...

You post all this info... wheres the data to support "valve float" over 47psi? And 47psi on what turbo? Stock?

Please post the dyno of your car at 47psi.

[Charged]

Originally Posted by 335dsleeper

So what valve springs?

You're saying porting and cleaning up isn't worth it, I tend to agree as the power levels we're at may not "need" it, that said, in the US when someone says "port the head" it usually suggest the entire head is getting gone through. i.e. cleaning the ports, blending bowls, valve job and ensuring springs/seals and retainers are functioning as designed and up tot he task. I'll have my head done eventually and I will focus on the valve job...

You post all this info... wheres the data to support "valve float" over 47psi? And 47psi on what turbo? Stock?

Please post the dyno of your car at 47psi.

You have 14 pages to read and figure it out.

[335dsleeper]

Originally Posted by Charged

You have 14 pages to read and figure it out.

Ha. I haven't seen anything earth shattering so far. Oh, except 47psi... using PSI as a measurement is hilarious... Was that 47psi on a KO4 or 47psi on a GT42? Comical...

Like I said... show me something.

[tuikku]

.
Exhaust valve do not know the size of the turbo.

Here you find some info and springs.

[DWR]

Originally Posted by tuikku

.
No
I have written in forums like this over ten years.
This is the first time that anyone who disagrees with me and is able to justify his views and can be right in real life.

Thank you.

... But this do not mean, that I agree with you.
We are not even near the level, when any kind of porting is necessary.
Except valve springs, they are very loose in MB, but even worst in BMW.
Stiffer springs increases fresh air in cyl.
Back pressure get valves floating after ~3,2bar (47psi)

Lower compression reduce cylinder working pressure but do not help heat stress.

We have a mutual respect for each other.
I completely agree on the porting, at the level we are talking about. We are not in disagreement

I'm going to start a new thread, so these kinds of more advanced tuning/modification ideas can be expressed/shared.

Cheers.

[335dsleeper]

Originally Posted by tuikku

.
Exhaust valve do not know the size of the turbo.

Here you find some info and springs.

Nor do valve springs know what 47psi is. What WHP/RPM are you seeing valve float at? PSI is irrelevent.

[DWR]

Originally Posted by 335dsleeper

Nor do valve springs know what 47psi is. What WHP/RPM are you seeing valve float at? PSI is irrelevent.

47 psi is a spring. A very long spring, with proportioanly small displacement. The more pressure the sooner you will see valve float.
This is not unlike the fact that it takes less force to open a poppet wastegate, as the backpressure builds. Hope that helps your understanding of the situation.

I have copied these last posts to the "Advanced Tuning and Mods" post.

[DWR]

Originally Posted by HeatherM35d

Maybe the true solution is a high flow head, lower compression, lots of boost and a high swirl piston design. But I don't want to give you details on the entire build. Getting a little side tracked on this thread with riddles.

Posted a new thread "Advanced Tuning and Mods", as a place for riddles.

You didn't mention camshaft. Sticking with stock? Please respond in that other thread.

[335dsleeper]

Originally Posted by DWR

47 psi is a spring. A very long spring, with proportioanly small displacement. The more pressure the sooner you will see valve float.
This is not unlike the fact that it takes less force to open a poppet wastegate, as the backpressure builds. Hope that helps your understanding of the situation.

I have copied these last posts to the "Advanced Tuning and Mods" post.

You've completely missed the point.

[DWR]

Originally Posted by 335dsleeper

You've completely missed the point.

You may be right. Perhaps you had difficultly expressing yourself.
Please make another try ... in the appropriate thread.

[TDIwyse]

Originally Posted by tuikku

.
This is difficult to explain even with my own language...

There is a small back pressure in exhaust pipe, that slows down gas flow, not much but ...
When that ends.
Flow and pressure across the turbine increases, or it seems that it will.
Then the only thing that resists gas flow is turbine, all the pressure comes now against it, total amount of flow does not decrease or increase.

If if the bigger pressure ratio now across the turbine wings tries to push the wing in higher revs to decrease back pressure, => boost pressure likes to rise and system stops it.
=> back pressure rises, nothing more happens.

If I release boost pressure a bit higher , turbine/compressor goes overspeed, or boost rises to sky.

"Smaller" exhaust pipe does not matter when turbo starts spooling, work.
But it helps to keep the (stock) turbo alive in extreme conditions.

Bigger turbo changes the whole idea completely.

It would seem using the external wastegate also changes the stock system behavior.

So, with the new electronic boost controller, I'm able to tailor the boost response across rpm. Attaching a couple example curves with their associated post turbine back pressure measurements. I'm sampling very close to the turbine exit, and I think the turbulent air in this region is causing the bumpiness in the curve. However, the trend line is also such that with increasing boost there's higher post turbine pressure which would seem to indicate more flow across the turbine. This correlation is consistent across all the boost curve shapes I've been looking at.

If I understood your explanation above, it would seem that I'm able to do things and measure responses that are at odds with what you were describing? But, with the EWG, I'm also not operating the turbos like they were being operated in a stock configuration.

I'm hoping to load up multiple boost vs rpm calibrations in the memory of the EBC (it will hold up to 6 separate profiles that can be swapped in with a few button pushes) so I can do back to back tests using PerfExpert to measure power output differences, along with various key parameters...

[TDIwyse]

Originally Posted by DWR

...Just trying to have a good discussion and learn. Some of us are not interested in a cookbook of what works in a 335d, we want to understand the principals ...

This.

I'm not motivated by trying to have an extremely fast car (there's way easier and cheaper options than this platform). I've just enjoyed the learning process and discussions.

Now ... I don't know which thread to post in anymore. This one or your new one?

[tuikku]

Originally Posted by TDIwyse

....
If I understood your explanation above, it would seem that I'm able to do things and measure responses that are at odds with what you were describing? But, with the EWG, I'm also not operating the turbos like they were being operated in a stock configuration...

No at all, sorry
As you can very well see, I like to write and express my opinion eagerly, though my English is what it is.

You have measured a lot, I did that also earlier.
Until I figured out, that the only thing that really matters, is amount of air, true amount that truly goes in cyl.
All attention should be focused on better airflow through the engine.
More air makes also all the other measurements looks better.
Always the best and easiest solution to my cars have been a bit bigger turbo.
And I have built a few.
Now, I am evil, but you really need a good quality hybrid or totally different, bigger turbo.
With modded cp-pump and hybrid you are quite easily able to have ~100hp more power.
Car works still perfectly in every day driving.

[Charged]

Stay here, new thread seems just for making fun.

[HeatherM35d]

Originally Posted by Charged

Stay here, new thread seems just for making fun.

Doesn't matter where I go..

[Charged]

^Sorry quote was ment to Tuikku

[DWR]

Originally Posted by TDIwyse

This.

Now ... I don't know which thread to post in anymore. This one or your new one?

Since you aren't working with hybrids and you are now controlling boost and testing various settings along the rpm range, that sounds somewhat advanced - compared to what others are doing here. But I don't want to become the forum police. Just added the new thread because others thought the posts were getting off topic, as often happen here.

[_TB_]

Sorry for bumping in on your _awesome_ 335d discussion - but does anybody know what the 325d head will flow? It has slightly smaller valves compared to the 330d and 335d.

I'm trying to figure out if a 330d (or even a 335d) head is needed to make good (350BHp ish) power with the 325d.