Entdrosselung Ansaugwege Passat 1,9 TDI AWX/AVF | Posts 32+

. . . and a shaky situation to boot: for example, in the lower sections at low speeds, there won't yet be any usable back pressure.
Following: even from a standstill (or with a strong tailwind, or in the slipstream of the rider in front...), the turbocharger still pumps .

Okay, here's the translation:

'right.'

However, this relieves the load on the turbo, even if it is not operating at its maximum capacity, because the pressure difference it has to overcome decreases.

Therefore, it's not pointless, which is essentially what I want to say.

Not without reason did Porsche cut a hole in the hood of the 968 CS Turbo, thereby gaining 2 horsepower through this effect via mechanical LDR at high speeds.

Best regards, Jochen.

Thank you everyone for the great contributions! I've learned that the idea isn't fundamentally wrong.

The question I'm asking myself now is whether it's possible to construct it as I described above, or whether I should be concerned about potential problems with water, dust, and other issues.

Hello RTDI-Tom,

Perhaps my experiences in this area can help you: I once tried to modify the entire plastic ducting system for the airflow, from the air intake to the airbox, on a Leon with an ARL engine, following exactly the same approach as you're considering.

My advice: Leave it as it is! It's not ideal, but in my humble opinion, the chance of achieving a noticeable improvement in terms of sound quality, LMM wear, and performance characteristics is much more realistic than achieving genuine breakthroughs.

My ARL engine had been frustrating me with a nasty, huge turbo lag, limiting it to only 2 turbo boost levels, and extreme sluggishness below 3500 rpm. (Now I know that the 1.9 PD engines produced after '96 weren't really the best design from the VAG group, and these issues are inherent to the design.) Everything is half-hearted, makeshift work , banana products, and not a source of pride for VAG ).

I also initially considered utilizing the Pitot tube effect and pressure build-up, in addition to removing the 'bottleneck' straw-like section between the 'water separator' and the 'filter box.' However, I ultimately failed due to issues with spray and the lack of suitable flexible pipes/materials, especially since I lack the motivation to design and fabricate a completely independent intake system that would separate the water, as the standard 'pre-filter box' behind the headlight seems capable of doing.
From my knowledge of avionics, I know that the pressure differences between the pitot tube and the static pressure port are actually negligible for our purposes of load alleviation, and moreover, they only become relevant at higher speeds.

What I've also learned is that I need to understand the complexity of the necessary mathematical models and the difficulty of the corresponding... Flow simulations are not even able to anticipate the factors that should be considered when designing the intake manifold of a modern passenger car.

Even the angle and position of the opening for the air flowing into the air filter housing can determine success or failure. One might think that the mass airflow sensor (MAF) characteristic does not reflect a realistic, objective airflow, but rather models the air mass based on the design of the intake system, drawing on measurement experiences from the development process. Every fold, every guide vane, every swirl, every disruption of the laminar flow, all influence the MAF sensor readings, usually negatively, and I suspect it's not just these factors. Regardless of whether it's a turbocharger or not, I meant that changing the architecture of the intake manifold to improve performance in one RPM range would likely be offset by a degradation in performance in another range. (Despite simulated LM-Max).

Here are a few more (in modern German ) 'no-nos,' as a yuppie would say:

- A second 'air inflow' into the airbox, for example from below, creates a counter-pumping effect that conflicts with the other airflow (e.g., the original airflow) and can even throttle the engine (only minimal pressure differences due to different flow conditions at the respective intake openings are necessary). The kinetic energy of the airflow that is not used is generously transferred to the environment in the form of sound and vibrating material, much like a didgeridoo (or however you spell it).

- Creating your own baffles inside the air chamber is a tedious and frustrating process of trial and error (due to the LMM).

-100 flexible pipes are not their own gravity-fed drainage system, and definitely require this feature if they are drawing air in the airflow.

You should not use -100 flexible pipes from hardware stores, even if they have a suitable temperature range, because their lack of rigidity and spiral profile disqualify them due to their resonant and flow-dynamic properties.

General. Sure, here's the translation:

'Tips:'

Pipes should always be smooth and relatively rigid, and should be adequately thermally insulated to protect them from 'hot' neighboring components. Ideally smooth, round, and gently curved aluminum.

Intakes should ideally be positioned in the airflow, never perpendicular to it or against it, otherwise the architecture will draw air out rather than in, even with a boosting effect. (Therefore, the wheel well area should always be approached with caution, as the pressure conditions there are likely to be unfavorable.)

If you're going to start experimenting, buy Ansys right away and get started. (The topic provides enough material for a dissertation.)

Buy all the plastic parts you might need for your experiments from online marketplaces (from 'emergency sales'), as a backup. (Everything is included.) Airboxes and seals, starting at just 5 euros.

Try not to suck in air from the left side of the battery (Does it pull it into the trunk better?).

Save yourself the trouble and just buy a CR product from BMW, Mercedes, or a Japanese manufacturer, and then marvel at the verschandeln engineering and long-term reliability *nervous laugh*.

Have fun!

Hello ObenbeiMutti (I always smile when I see your username).

Thank you very much for the very comprehensive answer. It contained many good suggestions, which apparently are based on your own experiences. I obviously didn't pay attention to the last sentence , because I've certainly put a lot of effort into my Golf, and I'm currently in the process of achieving a significant performance improvement.

What I've learned from your explanation is that this action carries a significant risk of creating a whole host of new problems, and the positive effect is not even remotely predictable.

So, I'll leave the slightly larger R32 DSG intake in place and won't do anything else.

Thank you again to everyone who participated in the discussion!

Okay, here's a weird question on the topic, although I might be completely wrong.

If the intake path is 'de-restricted,' relieving the load on the turbocharger, the mass airflow sensor should measure the corresponding amount of air at a lower boost pressure.

Now it really depends on the rule strategy of the MSG and how it handles this.

Either the air mass is prioritized, which would result in a decrease in the LD (likely referring to a specific metric or value).
(for the same engine power)

or the LD (lambda diagnostic) will be triggered, and the exhaust gas recirculation rate will be increased.

or emergency mode.


How's it going?

It's not actually that complicated:

When the intake manifold is modified to improve airflow, the turbocharger either spins up faster or requires less power to achieve the same level of boost, because the pressure difference across the turbocharger decreases (slightly).

LD is regulated, so it remains constant.
Assuming a constant intake air temperature and a constant low load torque (LLT), there is a linear relationship between load demand (LD) and motor torque (LM). So, nothing is changing here either.

It becomes problematic when the air mass sensor (AMS) is no longer optimally positioned in the airflow due to the modification, and therefore does not measure the entire mass of air.

Essentially, you are only reducing the necessary drive energy and, consequently, the rotational speed of the turbine shaft.

Best regards, Jochen.

Okay... I once removed the air intake snorkel from my ALH engine and then did a diagnostic log using VAGCOM.
I noticed that the LM (likely meaning 'Learning Machine' or a similar term) was equal to the target value, but the LD (likely meaning 'Learning Deviation' or a similar term) was lower.

Then, presumably, only the duty cycle of the N75 will change.

Thank you for the response.

Sure, here's the translation:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which translates to 'Sincerely' or 'Best regards' in English.

And how exactly did that manifest itself? Did you experience a performance loss due to the lower LD (lightness density)?
I've heard different opinions on that matter.