A3 TDI Intake Manifold: Cleaning & Polishing

Hello, fellow diesel enthusiasts,

I'm planning to clean and possibly polish the intake manifold on my heating oil-powered Ferrari.

Engine type: ASV.
Year of manufacture: 10/1999.
81 kW

Does anyone have any tips for this project?

Thank you in advance!!

Greetings from Lake Constance.

Cleaning the intake manifold can be beneficial after 50,000 km, especially if the exhaust gas recirculation (EGR) valve is functioning correctly. In my case, after just over 80,000 km, there was a significant amount of sludge buildup. However, I didn't remove the entire intake manifold because I consider the effort involved to be disproportionate to the benefit.
Without soot from the exhaust gas recirculation system, the oil mist from the crankcase ventilation system should, over time, keep things reasonably clean.
I wouldn't bother polishing anything here; you won't notice any difference in performance with turbocharged engines. Also, remember that a perfectly smooth surface is actually...
not offering the slightest flow resistance, minor surface imperfections from the manufacturing process can actually be advantageous here.
Here's a translation of the German text:

"What you can safely remove without worry: all sharp edges and corners. Regarding optimizations to your engine, I recommend taking a closer look at the plastic pipe connecting the turbocharger to the intercooler, especially the connection of the rubber hose coming from the turbocharger."

Best regards, Rainer.

Hello,

I cleaned the intake manifold, including the EGR valve, on my AJM engine (mileage: 25,000 km).

Effort:

- Materials (seals and screws): approximately 12 EUR.
- Time required: approximately 2 hours.

Since the manifold is located at the back, it's quite a fiddly job.
However, no special tools are required.

Hi Rainer K.

I cannot agree with that.

The boundary layer separation is, among other things, dependent on the thickness of the laminar boundary layer and the wall roughness.

You can find the formulas in the 19th edition of the DUBBEL, section B49.

Sure, here's the translation:

'Short example...'
Assuming an inner diameter of approximately 0.025 meters, and given a turbulent flow (Re = 2500), the calculated boundary layer thickness is 0.1667 mm.

Wandrauigkeit k: (This appears to be a German word or abbreviation, and without more context, it's difficult to provide a precise English translation. It might refer to 'wanderlust' or a specific term related to travel or exploration.)
Cast iron pipes: new, standard product --> k = 0.25..0.5 mm.
encrusted --> k = 1.5...5.0mm

According to Prandtl, hydraulically (or pneumatically) smooth pipes result in:
Boundary layer thickness / wall roughness >= 1.

Let's take the example: 0.25mm / 0.1667mm = 1.5.

Even with a new, well-cast iron piece, the surface is not hydraulically (pneumatically) smooth.

Assessment: Polishing the surface reduces aerodynamic drag.

Thank you for your information.

Greetings from Lake Constance.

Hi Tobias,

You seem to be quite fit .
Of course, I cannot determine the influence of surface roughness on the flow behavior of a gaseous medium through calculations, as I lack the necessary expertise.
However, I can assure you that the experience mentioned above was gained through experimental measurements on various engines (none of which were TDIs).
When dealing with minor surface irregularities, it should be noted that the oil layer that is always present in the intake manifold always creates a smooth surface.
Since I don't have a spare car available, here are two helpful links I found:
http://www-ifh.bau-verm.uni-karlsruhe.de/hydro/download/Kap07ps.pdf
http://www-ifh.bau-verm.uni-karlsruhe.de/hydro/download/Kap08ps.pdf
For informational purposes, I would like to know why golf balls are not polished but instead have numerous small dimples on their surface. This is because they are designed to fly as far as possible in order to minimize the number of strokes needed to get the ball in the hole.

Another question for Michael II: Approximately how thick was the sludge layer on your vehicle after 25,000 km, and did you drive every kilometer with a functioning EGR system? After over 80,000 km, the thickness was significant on my vehicle, 2-3 mm in the EGR valve, and in some places even thicker. In the intake manifold itself, it was thinner again.

Regards, Rainer.

Tobias wrote:

Hi Rainer K. I cannot agree with that. The boundary layer separation is, among other things, dependent on the thickness of the laminar boundary layer and the wall roughness. You can find the formulas in the 19th edition of the DUBBEL manual, section B49. Sure, here's the translation: "Short example..." Assuming an inner diameter of approximately 0.025 meters, and given a turbulent flow (Re = 2500), the calculated boundary layer thickness is 0.1667 mm. Wandrauigkeit k: (This appears to be a German word or abbreviation, and without more context, it's difficult to provide a precise English translation. It might refer to "wanderlust" or a specific term related to travel or exploration.) Cast iron pipes: new, standard product --> k = 0.25..0.5 mm. encrusted --> k = 1.5...5.0mm According to Prandtl, hydraulically (or pneumatically) smooth pipes result in... Boundary layer thickness / wall roughness >= 1. Let's take the example: 0.25mm / 0.1667mm = 1.5. --> That is to say, even with a new, well-cast cast iron piece, the surface is not hydraulically (pneumatically) smooth. Assessment: Polishing the surface reduces aerodynamic drag. Thank you for your information. Greetings from Lake Constance

.

Hello Rainer,

I always kept the AGR (automatic air recirculation) system turned on.
The deposits were approximately between 1 and 1.5 mm in size.

Hello,

Here's the explanation of why golf balls with dimples fly further than polished ones.

http://freenet.meome.de/app/fn/artcont_portal_news_article.jsp/84052.html

Greetings from the North Sea.

Andy.

Hello Rainer K,

Well, regarding my fitness... it's okay. Maybe a little information about me:

I work at ZF Getriebe GmbH in Friedrichshafen.
I work in the prototype development of automotive powertrain technology, specifically in the area of automatic transmissions, as a test engineer in the development of transmission control systems.
active

Unfortunately, I can't draw on your practical experience... (I've never tried polishing intake manifolds before.)

As far as I know, golf balls have these dimples to create spin. Just like a projectile fired from a gun has rifling in the barrel. This spin causes the golf ball or projectile to rotate. This rotation stabilizes the golf ball's trajectory.

You are right that wetting a surface with oil makes it 'smoother,' but the leveling effect of the oil is only in the hundredths of a millimeter range.

'Thank you very much for the information... and this forum is really great.'

I'll just give it a try!

Greetings from Lake Constance.

hello,
Here's another attempt to explain the dent.
Why did a particular motorcycle helmet have dents, even though it hadn't been involved in an accident?
The performance gain from a smooth surface plays a much smaller role in a turbo engine compared to a naturally aspirated engine. Optimizing transitions and radii is acceptable. However, in my opinion, aspects like boost pressure, intercooler air routing, and pressure regulation are more promising areas for improvement, considering the effort involved.
Please correct me if I'm wrong.
Best regards,
derteileklaus

"This thread is quite old, but: The indentations create turbulent airflow, which, in principle, increases resistance, but it shifts the point of flow separation on the back of the golf ball further back, so that the overall resistance is reduced. A similar effect occurs with too drastic cross-sectional or directional changes in the intake manifold. However, a smooth surface is better for an optimal contour, such as an airfoil."

hello,
Here's another attempt to explain the dent.
Why did a particular motorcycle helmet have dents, even though it hadn't been involved in an accident?
The performance gain from a smooth surface plays a much smaller role in a turbo engine compared to a naturally aspirated engine. Optimizing transitions and radii is acceptable. However, in my opinion, aspects like boost pressure, intercooler air routing, and pressure regulation are more promising areas for improvement, considering the effort involved.
Please correct me if I'm wrong.
Best regards, derteileklaus

I would wholeheartedly agree with that after several semesters of fluid mechanics and engine technology!

Tom.

Hello,
Here's another thing about it...
The performance improvement of the "Pollierer" might be more attributable to the cross-sectional enlargement achieved by using the milling tool before the polishing process?
Best regards,
derteileklaus