LLK die 10te: Größen und Leistungsstufen | Posts 64+

Hi Ulf,

Okay, I understand.
Now it would be interesting to know how much pressure loss such a low-loss cable has.



Regards,
DJ.

PS: Then I would rather switch to a low-latency keyboard and increase the pressure to 1.5 bar via software }.

dj1 wrote:

Hi Ulf, Okay, I understand. Now it would be interesting to know how much pressure loss such a low-loss cable has. Regards, DJ. PS: Then I'd rather switch to a low-latency keyboard and increase the pressure to 1.5 bar via software

.

Sure, go ahead and let us know the details later.

dj1 wrote:

Now it would be interesting to know how much pressure loss such a liquid cooling system has.

Depending on the size, design (cross-section of the air channels, turbulators, etc.), and volumetric flow rate (which is dependent on the motor and speed!), the pressure difference can be significantly lower than 0.1 bar or higher than 0.2 bar.

The description of the industrial TDI specifies values such as: pressure before the low-loss control valve (LLK) is 0.92 bar, and pressure after the LLK is 0.9 bar.
That would only be a pressure loss of 20 mbar due to the low-loss cooler, but some other data are simply unbelievable, for example, the behavior of the low-temperature circuit as a function of speed...

Sure, go ahead and let us know the details later.


Okay, let's wait and see.


It might take a while longer, as I still need to upgrade to a 12mm setup.


Regards,
DJ.

PS: @Ulf, I'm skipping the calculations . I have 50mm pipe fittings and 50mm pipes. Let's see what else we can get out of it for durable performance...

Hello again,

I've also been dealing with this topic for a very long time.

The differences between the two intercoolers in the G3 are the materials used for the core: one is made of plastic, and the other is made of aluminum. Unfortunately, both are only pressed against the cooling fins and can be pushed back under excessive boost pressure.

While I didn't bother to calculate the exact specifications because I wasn't sure how to do it, I did some research back then and came across intercoolers with so-called "turbulators." The principle is to create a turbulent flow, as Alex has already explained multiple times. Unfortunately, I haven't been able to compare one of these myself to a "standard" intercooler yet, but the temperature difference (delta T) should be significantly greater than that of a typical intercooler, even with the same dimensions. I plan to try it out sometime. If anyone has experience or data on this, I would be very interested to hear about it.
@Alex (and everyone who's interested)

"There's one thing I don't quite understand. The Reynolds number is calculated as (pipe cross-sectional area x length) / viscosity (in this case, the viscosity of air). Below a certain value for Re, the flow is laminar. Above that value, the flow becomes turbulent. But how do I determine this value? Or is it always 1 in such cases?"


Recently, I lent a friend my engine control unit (ECU) from my G3 AFN. He wanted to verify that the software produced significantly more power. His AFN is essentially modified in the same way as mine was back then; the only difference is that his AFN has an intercooler from a Mercedes-Benz Sprinter for cooling the intake air.
(For those who don't know how large an intercooler is, simply search for "intercooler" on a major online auction site; you will find several with pictures and often dimensions). In any case, this AFN engine didn't produce any soot particles during summer peak temperatures, whereas my car, equipped with the standard G3 intercooler, sometimes darkened entire stretches of land until we reduced the fuel injection amount.This AFN engine with the MB turbocharger showed me how much a large intercooler can improve performance. Unfortunately, I cannot provide any specific figures because the pump voltage characteristics were heavily modified, making it impossible to reliably determine flow rates. I haven't been able to perform any further measurements on the vehicle yet. Let's see if anything changes. The response time was also only slightly negatively affected by the large volume of the intercooler.
@Ulf

Ich weiß ja, dass Du sicher keine Klima hast und in sofern sollte dieser Platz, der normalerweise für den Klimakühler gedacht ist frei sein. Ebenfalls gehe ich davon aus, dass ein Fahrzeug ohne Klimakühler einen etwas kleineren Wasserkühler besitzt. In sofern kann ich mir nicht vorstellen, auch ohne Ahnug zu haben wie Dein Auto vorne im Detail aussieht, dass bei Dir vor dem WK kein Platz für einen LLK ist. Bei meinem G3 stand ich damals vor dem Problem, dass ich die serienmäßige Optik nicht groß verändern wollte, sprich Stossstange ausschneiden. Aber There are plenty of aftermarket parts available at reasonable prices that are likely much better than the standard part installed by the manufacturer.

It would be particularly interesting to calculate or estimate the new LLT (Lifetime Limit) and then compare it with the new measurement values, or even select a new LLK (Lifetime Kilometers) based on these criteria. I don't assume that you want to buy a new LLK from one of the companies mentioned here for 400 euros or more, plus the additional connection costs.

Are you just talking about the theory here, or do you actually plan to take action?
What specific benefits do you expect from this? Are you only looking to improve the thermal performance, meaning the environment and lifespan, or are you aiming for more power?

Best regards,
Thomas.

Thomas wrote:

Therefore, I can't imagine that there wouldn't be space for a front license plate holder at the front of your car, even without knowing exactly what it looks like.

Hi Thomas,

Are you back again?

In my car, there is only space for a slim air conditioning condenser in front of the water pump (with a depth of approximately 3 cm).
Otherwise, it's so cramped in there that I can't fit any air ducts (with an outer diameter of about 6 cm) in front of the water cooling system without having to "cut away" several mounting points for the front bumper.

Quote:

I'm not assuming that you want to buy a new LLK (Liquid Level Kit) from one of the companies listed here for 400 euros or more, plus the cost of any necessary accessories.

I expect to receive a custom-made SMIC (Sensor Module Interface Controller) in a few days with more than double the network capacity of the standard part. It won't be from the companies listed here, but unfortunately, the price is still high.

Quote:

Do you only want to improve the thermal management, meaning environmental impact and lifespan, or are you looking for more power?

Mainly the thermal management. Whether it's possible to add a few horsepower afterwards will be shown by logs related to air mass...

Hi Ulf,

Quote:

Are you back again?

Yes, you will never completely get rid of me.
I only have very little time during the current semester, and during the...
Unfortunately, the so-called "vacation" period is also when all the exams are held.

Quote:

I am expecting to receive a custom-made SMIC in a few days, which will have more than double the network capacity of the standard part. Although it's not from any of the companies posted here, unfortunately, the price is still comparable.

I'm looking forward to the results, especially the measured values.
Maybe you could also post a picture sometime.

My idea was that there's usually a crossmember located in front of the coolers, which among other things holds the bumper. You can typically attach a slightly thinner, longer auxiliary lighting bar to this crossmember, similar to what you see in dj1's photo. However, as you mentioned, it often requires cutting out a lot from the inside of the bumper. But that seems like it's probably not necessary now anyway, and this solution is definitely more elegant.

Quote:

Mainly thermals. Whether you can add a few horsepower afterwards will be shown by logs with the air mass.

You can definitely adjust the fuel injection amount, but that will likely bring your thermals back to how they were before.

Best regards,
Thomas.

Thomas wrote:

Quote: I am expecting to receive a custom-made SMIC in a few days. I am eager to see the results, especially the measurement values. Maybe you could also post a picture sometime.

Sure, everything will be posted!

Quote:

My idea was that there is always a crossbar in front of the coolers, which among other things holds the bumper.

. . . and it is usually possible to attach a slightly thinner, longer low-pressure coolant line to this crossbar. With this, the total lengths of pipes and hoses (and thus the "volume" at increasing load) between the compressor and the engine are roughly doubled compared to the SMIC, or even more.If there's some kind of delay implemented in the engine software for the soot level (when LD increases), that would likely need to be adjusted to avoid significantly increased soot values (possibly exceeding limits) during full-throttle operation.

@Thomas:

It's good to hear from you again!

Regarding your question:

Quote:

I'm not entirely clear on something. The Reynolds number is calculated by multiplying the pipe cross-section by the length and dividing by the viscosity (in this case, the viscosity of the air). Below a certain value for Re, the flow is laminar. If the value is above that, the flow becomes turbulent. But how do I determine this value? Or is it always 1 in such cases?

For relatively smooth pipes and similar geometries, the transition from laminar to turbulent flow occurs at a Reynolds number of approximately 2100.
In the case of a low-head hydraulic structure, the conditions are quite different. First, one must determine the equivalent hydraulic diameter and substitute it into the formula. Furthermore, steep transitions cause flow reversal to occur at much lower Reynolds numbers (so-called "stumbling effect").
The mentioned heat exchangers likely possess so-called "vortex generators," which are also found in AGR (Advanced Gas-cooled Reactor) coolers.
This has two positive effects as a result:

- The turbulence of the flow is increased, which significantly enhances heat transfer, especially in areas close to the boundary layer.

- Turbulent flow persists for a longer duration near sharp bends compared to laminar flow, resulting in less "stagnant" surface area within a liquid cooling system, and therefore less wasted surface area.

Regards,
Alex.

Hello Alex,

That helped me a lot. Thank you. I'm risking overstepping my bounds by saying this.
How do I determine the equivalent hydraulic diameter?

I've checked several books already, but I haven't been able to find anything relevant. I also won't be able to make it to the library this week. If it's too extensive a topic, I would be happy with just a reference work that you can suggest.

As far as I can tell from seeing these "vortex generators," they are simply small deflectors.

Best regards,
Thomas.

Hello,

I've now installed my upgraded SMIC (pictures will follow later).
Due to space constraints, the increase in size was primarily in depth (plus 74%), while the front surface area of the network is only increased by 44% compared to the previous series.
The cross-sectional area for the cooling air flow has been increased by approximately 74% due to a higher fin density on the front of the heat sink.
In addition, the fin structure is slightly coarser/more open than in the standard part, which means that the cooling air flow per unit area of the grid may also be higher - provided that the lower section of the grid does not slow down the cooling air accordingly.

The total surface area of the charge air ducts (which represents the heat transfer area between the intake and cooling air) has more than doubled.
The new LLK also features turbulators in the LL channels and is therefore fundamentally comparable to the standard SMIC in its design.


Previous log data:
The approximately threefold increase in the mass of the new LLK (Liquid-cooled system) from about 6 kg (heat storage capacity) results in a much slower rise in the LLT (Liquid temperature), for example, when shifting to 3rd gear with full throttle starting at approximately 1300 rpm . LLT on the standard part: up to about 50 K above AT (Ambient Temperature), Upgrade: an additional 24 K above AT.
However, on the highway (BAB), the advantage of the larger SMIC decreases significantly; for example, after 40 seconds within the maximum power range (Pmax), it shrinks to a mere 9-10 km/h.


If the thermal resistance were halved (analogous to more than doubling the network volume or heat transfer area), my rough calculation suggests that a reduction in the final LLT at Pmax from 54 K to approximately 34 K could be achieved through AT, representing a decrease of about 20 K.

The actual reduction of 9-10 K corresponds (coincidentally?) only to the pure growth of the network's surface area in terms of calculation, as if the increased network depth played no role at all.

Could it be that the cooling air supply in the wheel well is so poor (despite the sealed airflow between the spoiler grille and the radiator, and with the intake grille fully open!) that only the small standard radiator can be utilized to its full potential, while the upgraded radiator suffers from a lack of cooling air?
The inlet area of the spoiler grille is now only about half the size of the fin surface of the intercooler.

Or could slots in the inner fender, designed to channel warm exhaust air towards the front wheel, potentially provide a noticeable improvement (if I recall correctly, for example, the Audi TT had such slots)?
The lower right corner of the rear panel of the battery box is located only about 3 cm in front of the inner fender, and due to the curved shape of the plastic wall, its average distance from the battery box is approximately 10 cm.

Hello Ulf,

Even though the success hasn't been as complete as you expected,
I think that it was still a step forward.

The slots in the wheel arch liner might potentially help. However, depending on the time and effort involved, you could also test this without cutting anything.
Simply remove the inner fender liner and measure the temperature directly behind the intercooler. Then reinstall it and measure again. This way, you'll definitely know how much of a temperature difference the absence of the inner fender liner makes for the intercooler.

Another option would be a small electric fan placed behind the liquid cooler. I've seen that before. The question is whether it will restrict airflow at higher speeds or not. That depends on the specific fan.

The previous owner of my car must have been driving very low to the ground with large rims, because there's an oval piece missing from the wheel well. It looks like it was torn off by a tire when the steering wheel was turned. That's why I've always had "these slits" there.

I'm looking forward to seeing the pictures.

Best regards,
Thomas.

Thomas wrote:

Just remove the inner fender liner once and measure the temperature directly behind the intercooler. Then reinstall it and measure again. That way, you'll definitely know how much of a temperature difference the absence of the inner fender liner makes for the intercooler.

Hi Thomas,

Unfortunately, I don't have a suitable remote thermometer that can be read while driving.

Here's an idea I had:

A differential pressure gauge made from a single piece of clear tubing bent into a U-shape and partially filled with water, reacts to pressure differences by showing an uneven water level.
I'm simply extending the "pressure connections" (the top ends of the U-shaped pipes) with aquarium tubing all the way to the rear of the LLK (likely referring to a radiator or cooler), and to the inner fender on the rad side, and installing the "instrument" inside the passenger compartment.

If, while driving (at least from 100 km/h), a lower pressure is detected in the wheel well compared to behind the radiator, then holes in the housing could be used to draw air from behind the radiator, thereby improving the cooling airflow through the radiator .

Let's see when I find the time to do that...

Hello.

@ulf

So, opening the wheel well at the level of the lower control arm releases a significant amount of coolant. I determined this by installing a sensor at both the inlet and outlet.
It's definitely worth it.


Best regards, Cosi.

I was just thinking about it on my way back from the cafeteria: There was a Touareg V6 TDI with a broken steering wheel --> It also has slots in the wheel arch. And because I was curious: even on both sides. Does it have two intercoolers, or is there an oil cooler on the other side ?

Cosi wrote:

So, opening the wheel well at the level of the lower left corner releases a significant amount of coolant. I determined this by mounting a sensor at both the inlet and outlet. It definitely pays off.

Hi,

That's interesting!
What kind of sensors are you referring to? Are you talking about low-temperature sensors at the input and output of the liquid cooling system (LCS)?

What type(s) of vehicle are your experiences based on?

By how much did the Lower Limit Temperature (LLT) decrease in the maximum power (Pmax) range due to the openings?

"In any case" might not be entirely accurate: For example, Rainer documented different results on the A3.
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

mahk wrote:

There was a Touareg V6 TDI with a broken steering wheel --> It also has the slots in the wheel well.

AFAIK, the V6 engine has always had (or almost always has) two linkage components.
Are the slots actually punched out, or are the openings more like louvers that point downwards to prevent the tire from splashing water, mud, etc., onto the LLK (Low-Level Crossing) through the holes?