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

Hi Ulf,

Okay, I understand.
Now, it would also 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 also 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:

It would also be interesting to know how much pressure loss such a LLK 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 below 0.1 bar or above 0.2 bar.

The description of the industrial TDI specifies, for example, a value of 0.92 bar for LD before LLK, and 0.9 bar for LD after LLK.
That would only be a 20 mbar pressure loss due to the low-loss cooler, but some other data points are simply unbelievable, for example, the LLT (low-loss transformer) behavior 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.

"I didn't bother to calculate it myself because I didn't know how to calculate an intercooler, but 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 several times. I haven't been able to compare one of these intercoolers to a 'standard' one myself yet, but the temperature difference (delta T) should be significantly greater than that of a 'typical' intercooler, given the same dimensions. I'll try one out sometime. If anyone has experience or data on this, I'd be very interested."

@Alex (and everyone who's interested)

"There's one thing I don't quite understand. The Reynolds number is calculated by multiplying the pipe's cross-sectional area by its length and then dividing by the viscosity (in this case, the viscosity of the air). Below a certain value of Re, the flow is laminar. Above that value, the flow becomes turbulent. But how do I determine that value? Or is it always 1 in this kind of situation?"


Recently, I lent a friend my engine control unit (ECU) from my G3 AFN. He wanted to verify that the software produced a significant increase in power. His AFN is essentially modified in the same way as mine was back then, the only difference being that his AFN has an intercooler from a Mercedes-Benz Sprinter for cooling the intake air.
"For those who aren't familiar with the size of an intercooler, you can search for "intercooler" on a large online auction site; you'll find many with pictures and often dimensions. In any case, this AFN engine didn't produce any soot particles, even at summer's peak temperatures, while my car, with the standard G3 intercooler, sometimes darkened entire areas 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 can't provide any specific figures, as the pump voltage characteristics were heavily modified, making it impossible to reliably determine any flow rates. I haven't been able to perform any further measurements on the vehicle yet. Let's see, maybe something will come of it. The response time also only deteriorated slightly due to the large volume of the intercooler.

@Ulf

I know you probably don't have air conditioning, so that space, which is normally intended for the air conditioning condenser, should be free. I also assume that a vehicle without air conditioning has a slightly smaller water cooler. Therefore, I can't imagine, even without knowing exactly what your car looks like in detail, that there wouldn't be space for an oil cooler (LLK) in front of your water cooler. With my G3, I had the problem that I didn't want to significantly change the original appearance, meaning cutting the bumper. But there are plenty of oil coolers available at a reasonable price, which are certainly much better than the standard part.

It would be particularly interesting to calculate or estimate the new LLT (Lifetime Learning Time) and then compare it with the new measurement values, or even select a new LLK (Lifetime Learning Kit) based on these criteria. I assume you don't 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, 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

in front of your front bumper, even without knowing what your car looks like in detail. Hi Thomas,

Are you back again

Quote:

? 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, the space is so tight that I can't fit any radiators (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.

I'm not assuming that you want to buy a new LLK (Liquid Cooling System) from one of the companies listed here for 400 euros or more, plus the additional connection accessories. I'm expecting to receive a custom-made SMIC (System Memory Interface Chip) in a few days, which will have more than double the network capacity of the standard part.

Quote:

Although it won't be from the companies listed here, the price is unfortunately still high.

Do you only want to improve the thermal management, meaning the environment and lifespan, or are you looking for more power? } Mainly the thermal management. Whether you can then add a few horsepower needs to be shown by logs with the 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, during which all the exams are held, is also affected.

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 is not from the companies posted here, the price is unfortunately still high.

I'm looking forward to the results, especially the measured values.
Maybe you could 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 radiator (LLK) to this crossmember, similar to the picture from dj1. However, as you mentioned, this often requires cutting out a lot of material from the inside of the bumper. But it seems that's probably not necessary anymore, 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.

Adding more fuel injection will definitely work, but it will also mess up your thermals again, just like 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, I'll do that!

Quote:

My idea was that there is always a crossmember 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 crossmember. }. This means that the total lengths of the 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 opacity (when LD increases), that would likely need to be adjusted to avoid significantly increased soot values (possibly exceeding the limits) during full-throttle emissions testing.

@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. Above that value, the flow becomes turbulent. But how do I determine this value? Or is it always 1 in such a case?

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-Reynolds number flow, the conditions are quite different. First, the equivalent hydraulic diameter must be determined and used in the formula. Furthermore, steep transitions cause the flow reversal to occur at much smaller Reynolds numbers (so-called "stall effect").
The LLKs mentioned 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 around sharp bends compared to laminar flow, resulting in less "stagnant" surface area within a liquid cooling system, and therefore less surface area that is not effectively utilized.

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, 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, I would also be happy with a reference work that is mentioned.

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 the depth (plus 74%), while the front surface area of the network is only increased by 44% compared to the previous model.
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 fin may also be higher - provided that the lower fin section 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 charge air and the 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 mass of the new LLK (Liquid Cooling System) from about 6 kg (heat storage capacity) results in a much slower increase in the LLT (Liquid Cooling Temperature) on the country road, for example, when shifting to 3rd gear with full throttle from approximately 1300 rpm. LLT for the standard part: up to about 50 K above AT (Ambient Temperature), Upgrade: about 24 K above AT.
However, on the highway (BAB), the advantage of the larger SMIC (presumably referring to a type of vehicle or component) diminishes, with the difference in performance within the maximum power range (Pmax) shrinking to just 9-10 km/h after 40 seconds.


If the thermal resistance were halved (analogous to the more than doubling of the network volume or heat transfer area), my rough calculation suggests that a reduction in the final LLT (Lowest Load Temperature) at Pmax from 54 K to approximately 34 K could be achieved through AT (Active Temperature control), 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, as if the increased network depth played no role whatsoever.

Could it be that the cooling air supply in the wheel well is so poor (despite the sealed air duct between the spoiler grille and the radiator, and the fully open intake grille!) 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 grid is now only about half the size of the fin area of the radiator.

Or could slots in the inner fender, designed to channel warm exhaust air towards the front wheel, potentially provide a noticeable improvement (as far as I recall, the Audi TT, for example, had such slots)?
The lower right corner of the rear panel of the LLK (likely referring to a specific vehicle component) is located approximately 3 cm in front of the inner fender, and due to the curved shape of the plastic wall, its average distance from the LLK is likely around 10 cm.

Hello Ulf,

Even though the success hasn't been as complete as you might have hoped,
I think that, despite everything, 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 cooling unit. I've seen that before. The question is, does it restrict the airflow at higher speeds, or not? That depends on the fan itself.

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 radiator. Then reinstall it and measure again. That way, you'll definitely know how much temperature difference the absence of the inner fender liner makes for the radiator.

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, U-shaped tubing filled with water reacts to pressure differences by showing a tilted water level.
I'm simply extending the "pressure connections" (the top ends of the U-shaped pieces) with aquarium tubing all the way to the back of the LLK (likely referring to a radiator or cooler) and to the inner fender on the wheel 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 area of the wheel arch 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 left corner 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 installing a sensor at the inlet and another at the outlet in each case. So, it is definitely worth it.

Hi,

That's interesting!
What kind of sensors are you referring to? Are you talking about LLT sensors at the input and output of the LLK?

What type(s) of vehicle(s) is your experience based on?

By how much did the LLT (Lower Limit Temperature) decrease in the Pmax (maximum power) 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 (almost always) has 2 LLK.
Are the slots actually punched out, or are the openings more like louvers that are oriented downwards, so that the tire doesn't splash water, mud, etc. onto the LLK (low-lying vegetation) through the holes?