Differences in fill levels between the cylinders?

Hello,

Does anyone here have data on constructive and variation-related air supply differences in TDIs and similar mass-produced engines without cylinder-selective intake control actuators (if such things already exist)?
The greater the differences in air mass between the cylinders, the sooner one must stop (with a rational approach) when tuning, as the cylinder with the lowest air mass may begin to overheat or produce excessive soot.

As a response to this issue, some tuners offer to modify the intake passages of individual cylinders using a flow bench to achieve equal values. But which values are being adjusted?
If the measurement method relies solely on pressure losses at constant flow rates, it does not, from the outset, reflect the actual flow conditions, where flow resistances and speed-dependent oscillations in the fresh gas column overlap.
Here, I'm wondering if the oscillation behavior of the air columns within each cylinder is the same.
Or do the inevitable differences in shape, starting from the branching point in the intake manifold, create such individual vibration patterns that corresponding (constructive) differences in the static flow resistance can result in a more uniform air distribution overall, compared to uniformly minimized flow resistance before each intake valve?
Then, optimizing via a flow bench would be, at best, a case of "improvement through worsening"?

Hi Ulf,

Regarding this topic, I can only think of the differences in the intake manifolds of the latest TDI engines.
Previously designed more like a tree, they are now junction boxes with four identical outlets.

Take a look at these socks:
1Z - ASV - BMR - CBBB

dieselmartin wrote:

Take a look at the following socks: 1Z - ASV - BMR - CBBB

Unfortunately, I don't have anything like that in my grab bag.
But if someone could post photos or links online, all the readers would benefit from it .

I also just did a Google search - and that's how I found most of MY pictures .

[img]/download.php?id=1137[/img]

[img]/download.php?id=1854[/img]

[img]/download.php?id=1916[/img]
It's interesting that the swirl flaps were added, which means the internal design of the part has become significantly more complex.



http://junge-autoersatzteile.de/auctionstudio/1210/Pictures/201103/IMG_3512_800x600.jpg
http://junge-autoersatzteile.de/auctionstudio/1210/Pictures/201103/IMG_3511_1_800x600.jpg

m;

I would not link to something that has not been authorized by the owner. That can quickly cause stress.

I am allowed to include a link, but I am not allowed to embed it.

ulf wrote:

Hello, Does anyone here have data on constructive and variation-related air supply differences in TDIs and similar mass-produced engines without cylinder-selective intake control actuators (if such things already exist)?

Yes, I can (am allowed to), but I can't provide any further details.
But I can provide you with other information that might be helpful.

Quote:

The greater the differences in air mass between the cylinders, the sooner one must stop (with a rational approach) when tuning, as the cylinder with the lowest air mass may begin to overheat or produce excessive soot.

Correct.

Quote:

If the measurement method relies solely on pressure losses at constant flow rates, it does not, from the outset, reflect the actual flow conditions, where flow resistances and speed-dependent oscillations in the fresh gas column overlap. Here, I'm wondering if the oscillation behavior of the air columns within each cylinder is the same.

No! It's definitely not the same!

If you want to achieve a significant improvement, you need to start much, much further down.
Keyword: Compression differences and residual volume in the open thorax.
The residual volume can vary significantly, up to 10%, between individual cylinders. It should quickly become clear to you what this means for the compression and combustion process. It should be clear to you that this can also lead to uneven settling behavior.
....

In racing engines, the cylinder displacement is measured with extreme precision. Only with this can you reach your absolute maximum.

Quote:

Or do the inevitable differences in shape, starting from the branching point in the intake manifold, create such individual vibration patterns that corresponding (constructive) differences in the static flow resistance can result in a more uniform air distribution overall, compared to uniformly minimized flow resistance before each intake valve?

"OE" is foregoing a potentially overly complex manufacturing process in favor of certain "PSe" products. Here, the limitations are clearly the large-scale production and the number of units.
Of course, the goal will be to find a good compromise, but there is no room for engines running at their maximum capacity in mass production.

Quote:

Then, optimizing via a flowbench would be, at best, a case of "improvement through worsening"?

No, not necessarily, but unfortunately, it's only half the rent.

You need to see the whole thing as a system, in conjunction with the ZK (presumably a specific component) and the pistons. Only then are you on the right track to uncovering the complete truth.

Bertil wrote:

But I can provide you with other information that might be helpful.

Okay, thank you for that.

Quote:

Quote: The greater the differences in air mass between the cylinders, the sooner one must stop with (sensible) tuning, if the cylinder with the smallest air mass begins to overheat or produce excessive soot. Correct.

That would be the first explanation I can understand for test bench agreements instead of Flash+cash+go.
However, even with the TDIs that don't have factory-installed restrictors, I still believe that the limit can be visually determined on the road with a good software foundation (which doesn't overload the turbocharger from the start and includes a sensible fuel injection adjustment). This can be achieved by programming and adjusting the fuel quantity curve over the RPM range in multiple stages, such that the vehicle behind only sees a slight haze of smoke at most.

Or am I completely wrong about this?

Quote:

Quote: Here, I wonder if the vibrational behavior of the air columns within each cylinder is the same? No! It's definitely not the same!

. . . and it probably wouldn't be even if, by some chance, every cylinder had the same residual (combustion chamber) volume?

ulf wrote:

... However, even with the TDIs that don't have factory-installed restrictors, I still believe that the limit can be visually determined on the road with a good software foundation (which doesn't overload the turbocharger from the start and includes a sensible fuel injection adjustment). This can be achieved by programming and adjusting the fuel quantity curve over the RPM range in multiple stages, such that the vehicle behind only sees a slight haze of smoke at most. Or am I completely wrong about this?

No, you're not entirely wrong. However, I find the statement "... a slight haze of soot..." to be too subjective. Furthermore, I believe that the limit (for EU3/4) is already exceeded when a visible layer of soot is present.

By the way, I've recently seen several diesel vehicles with factory-installed exhaust systems that were visibly emitting a lot of smoke under full load. That worries me more.

Quote:

. . . and it probably wouldn't be, even if, by some chance, every cylinder had the same residual (combustion chamber) volume.

Ideally, yes. But for that to happen, the intake manifold must also be equally "ideal."
That's why I mentioned above that modifying the intake manifold is only half the solution.

Bertil wrote:

By the way, I've recently seen several DI vehicles with factory-installed stoppers that were visibly smoking heavily under full load. This is causing me more concern.

In what direction? Was there cheating involved in the Type BE exam?

Quote:

Quote: ... and it probably wouldn't be, even if, by some chance, every cylinder had the same residual (combustion chamber) volume. Ideally, yes. But for that to happen, the intake manifold must also be equally "ideal." Therefore, I wrote above that modifying the intake manifold is only half the solution.

An ideal manifold probably has a shape that is more like...
"Collection bin with 4 pipe sections of identical shape and length for connection to the central system."
such as the common TDI adapters for VP and PD injectors?

ulf wrote:

Bertil wrote: By the way, I've recently seen several DI vehicles with factory-installed stoppers that were visibly smoking heavily under full load. This is causing me more concern. In what direction? Was there cheating involved in the Type BE exam?

I highly doubt that, but I've come to the point where I consider nothing impossible anymore... .
What causes excessive smoke from a diesel engine? -> It's likely due to a lack of air combined with an excess of fuel. So, something must be wrong! Even in vehicles equipped with a DPF (Diesel Particulate Filter), this level of smoke emission should be significantly reduced.
I believe it's either due to major defects or poorly programmed CT (Computed Tomography). That gives me a headache.

Quote:

An ideal bridge probably has a shape that is more like... "Collection bin with 4 pipe sections of identical shape and length for connection to the central system." such as, for example, the common TDI adapters for VP and PD injectors?

Well, the bridge is actually far from ideal. But in terms of effort, it's certainly ideal enough.
However, if you take a closer look at the relatively roughly cast intake manifolds, you'll see that there are significant differences. The manufacturing process is extremely "inaccurate".
Currently, more and more intake manifolds are being manufactured from plastic. This is not only due to weight and cost considerations, but also, "coincidentally," to precision requirements. The plastic material is significantly smoother on the inside, and therefore has lower friction compared to the aluminum intake manifolds produced using sand casting.
Does the ZK still remain in the chain ?

Bertil wrote:

[What causes excessive smoking in a diesel engine? -> Lack of air with excess fuel. So, something must be wrong! Even in vehicles equipped with a DPF (Diesel Particulate Filter), this level of smoke emission should be significantly reduced. I believe it's either due to major defects or poorly programmed CT (Computed Tomography). That gives me a headache.

Or do you happen to always see the "regeneration" content, where the so-called "cleaners" are blowing all sorts of garbage out?

Quote:

Currently, more and more intake manifolds are being manufactured from plastic. This is not only due to weight and cost considerations, but also, "coincidentally," precision reasons. The plastic is significantly smoother on the inside and therefore has lower losses compared to aluminum intake manifolds manufactured using sand casting.

That makes sense, but what is the relationship between the narrowest flow cross-sections at the open intake valve vs. Suction channel disconnected?
In the past, longer valve opening angles and lift were a common tuning method, and it was probably there that the bottleneck was located.