LLK-Tuning: Mehrleistung durch weniger Ruß? | Posts 16+

Therefore, I suppose I have only optimized this.
Well, optimization is also a kind of tuning, isn't it?
And it was about whether tuning the intercooler, or using a larger intercooler, or even using an intercooler at all, could result in increased performance.
And this is the case. Even though this effect is only noticeable in the summer, it is still present.
Therefore, I consider this to be an LLK optimization.

Leigh wrote:

Therefore, I suppose I have only optimized this? Well, optimization is also a kind of tuning, isn't it? ..

Hi,
After all the back and forth, I assume that your car (or the engine type) deviates from the general rule described in the LLK tuning article.

Quote:

. . . that in a TDI engine, increasing the air mass through intercooler tuning or increasing boost pressure can only result in a power increase if it allows for a higher fuel injection volume -> meaning that "initially," the air mass (and soot) limit must be at its lowest. Most TDIs are designed from the factory in such a way that, under normal operation, the soot limit is set above the torque or driver-requested power limit. Therefore, an LLK (Low Pressure EGR) tuning cannot necessarily provide a noticeable increase in power in this case. Otherwise, the maximum possible gain from an intercooler tuning can be estimated based on the difference between the air mass and the next higher limit: for each mg of difference, approximately 2 to 3% more torque or power can be expected in the relevant speed range - provided that the intercooler modification increases the air mass limit at least to the value of the next higher limit.

It would be interesting if we had before-and-after measurements from a sample of your car, as that would help us better understand exactly what happened.

If you have a Serein LLK (likely referring to a specific type of equipment), it would take approximately 30 minutes to disassemble.
Brauch das Teil aber komplett, also incl. Hoses.
Then you can measure.
And then, with a large language model again!

Unfortunately, I don't have those parts anymore.
Why not!

Leigh wrote:

If you have a Serein LLK, the re-equipment would take about 30 minutes! Brauch das Teil aber komplett, also incl. Hoses. Then you can measure. And then, with a large language model again! Unfortunately, I don't have those parts anymore. Why not!

Hi.
"By 'a similar model of your car,' I meant a car of the same type that happens to be undergoing modifications soon, but not specifically your car."

I probably phrased that poorly, sorry.

Hi everyone,

How about this approach:

Assuming that a specific fuel injection amount (X) results in a flame of a certain size or volume within the cylinder, and considering that this is a diesel engine, the flame does not completely fill the combustion chamber. When the diesel fuel is introduced into the air, it initially combusts with the oxygen it is in direct contact with, which is the volume of the flame. If there is not enough oxygen within the flame to completely burn the fuel, the remaining fuel is gradually burned by the surrounding air and its oxygen content through turbulence. Consequently, the size of the flame increases.
This would be very clearly visible in a slow-motion recording.

The fact is that a better intercooler allows more air to enter the cylinders.
With the same flame volume and the same amount of fuel injected (X), the combustion should complete more fully within the same time period compared to before. Could this optimized combustion be the source of the increased power output?
It's well-known that some tuning methods inject a disproportionately large amount of diesel fuel for the amount of extra power gained. This can largely be explained by the fact that the injection occurs later in the cycle. However, the extra fuel is injected into a location where diesel has already been burned and consumed the oxygen. Therefore, the additional fuel must first be mixed with the fresh air (oxygen excess) still present in the edges of the cylinder before it can burn.

While perhaps not practically feasible, it's worth considering: what happens if you supply a motor with pure oxygen instead of air, while maintaining a constant fuel injection rate? I suspect the power output would increase because the combustion process would occur much faster. This is also evident in an acetylene-oxygen torch. With a small amount of oxygen, the flame is large, but as the amount of oxygen increases, the flame becomes smaller. This is likely because the acetylene burns faster and more completely immediately after exiting the nozzle, all while the acetylene flow rate remains constant.
Wouldn't a faster combustion rate increase the efficiency and, consequently, the power output of an engine?

Regards,

Eike.

eike wrote:

The fact is that a better intercooler allows more air to enter the cylinders. With the same flame volume and the same injection amount X, the combustion should complete more fully within the same time period than before. Could this optimized combustion be the source of the increased power output?

Hi Eike,
Achieving higher power output with the same amount of fuel injection indicates an increase in efficiency, but based on the discussions here, even with 20°C cooler intake air, the improvement should be at most 1%, which would be practically imperceptible.
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.

Quote:

It is well known that 10ct-tuning often injects a disproportionately large amount of diesel compared to the increase in power achieved. This can largely be explained by the fact that the injection occurs later. However, the extra fuel is injected at a point where diesel has already been burned and consumed oxygen.

IMO, the late-injected portion is primarily burned so inefficiently because, by that point, the useful stroke of the piston is essentially already halfway over, and the injected fuel mixture therefore has less time to perform useful work (the keyword here is "isobaric process").
(As a balancing measure, chip tuning often involves advancing the fuel injection timing and shifting the overall process somewhat towards a homogeneous charge combustion process.)
The further delayed burn time "outside in the combustion chamber," in my opinion, only exacerbates the problem, but probably isn't the main issue.

Hi,


Could you please explain that using the concepts of equal pressure and equal space?

Is that always only 1%, and what does that depend on?



Best regards,

Herb.

Golfkeks wrote:

Could you please explain that using the constant pressure and constant volume processes?

Hi,
roughly translated, with no guarantee of accuracy...

Constant volume combustion: All fuel is burned without changing the combustion chamber volume (an ideal scenario). This results in maximum pressure at top dead center and, overall, the highest power output, because all (usable) energy from the fuel can "work" throughout the entire power stroke.

Constant pressure combustion: The combustion process is designed to maintain a constant cylinder pressure during the power stroke by carefully controlling the fuel injection. This results in a lower peak pressure and a reduced thermal efficiency.

We kindly request corrections from the mechanical engineers who have studied this.

Hello Ulf,


Basically correct.
Just one more point: in gasoline engines, the isochoric process, which is the theoretical comparison process, largely occurs in the same way in practice. In diesel engines, we have both processes overlapping. At partial load, there is more of the isochoric process, while at full load, the isochoric component becomes larger because the larger amount of fuel at full load takes longer to be injected and combusted. This is the main reason for the high-pressure injection systems in modern diesel engines, which allow a larger amount of fuel to be injected in a shorter time (and the droplets become smaller, as do the emitted particles, resulting in a net reduction). You probably already know this, but I just wanted to mention it *know-it-all*.

Best regards, Uli.

Hello everyone,

I once had an idea inspired by Ulf, and it was as follows:
roughly calculate a formula; estimate a formula.

P*V = M*R*T (constant)

Here's what I've estimated:

Boost pressure: 1 bar.
Temperature 1, located behind the intercooler: 120°C.
Temperature 2 (after tuning), located behind the coolant pump, is 50°C.

For the air mass, an empirical value can be used here.
are used because the air mass is proportional to the...
Air temperature stable.

With a delta T of 70 Kelvin, the...
To reduce the air mass by approximately 1.4%.

Whether the difference in performance is ultimately noticeable.
I can't imagine that.

Regards,
Hturbo01

One thing to keep in mind is that the larger intercooler increases the volume of the 'intake manifold' after the turbocharger, which means it takes longer for the system to reach the desired pressure.

I hope I don't stand out for making a particularly simple or naive contribution...

Best regards, R00KIE.

Hello,

Quote:

P*V=M*R*T (constant) Here's what I've estimated: Boost pressure: 1 bar. Temperature 1, located behind the intercooler: 120°C. Temperature 2 (after tuning), located behind the coolant pump, is 50°C. For the air mass, an empirical value can be used here. are used because the air mass is proportional to the... Air temperature stable. With a delta T of 70 Kelvin, the... To reduce the air mass by approximately 1.4%

.

"I'm sorry, but if you set P*V/R = M*T = constant, it means that M is proportional to 1/T. Dividing the two temperatures in Kelvin gives you the mass change, and I'm getting 21% in my calculations. That should be quite noticeable... However, 120°C is more in the range of uncooled intake air. A standard intercooler shouldn't allow the temperature to be more than 40°C above the outside temperature, otherwise it's probably a design flaw. If you add another 20°C for additional cooling in a tuned intercooler, it's still only 6.5%. Even that is quite noticeable. However, a reasonably well-sized standard radiator will likely dissipate less than 20°C."

Best regards, Uli.

Hi.

The NOx emissions are significantly lower. This is one of the main effects of a low-temperature combustion (LTC) process. Therefore, a larger LTC system can be recommended, even if it doesn't increase performance, because it definitely reduces NOx emissions.
The reduction of NOx emissions achieved through lower intake air temperature does not have any drawbacks. Usually, reducing NOx emissions requires accepting poorer combustion conditions and lower efficiency (for example, when using exhaust gas recirculation or lowering the compression ratio).

Best regards, Ernst


That's nice and good. However, the area that is traversed during the MVEG cycle is in the partial load range. There, the boost pressures are not as high, the air is not as hot, and the intercooler has hardly any influence. The intercooler only serves to reduce the temperature at full load, in order to get more air into the engine and thus more power (if you adjust the fuel injection accordingly) . In principle, reducing NOx emissions is not of interest at full load, because a measurement for classifying exhaust emissions does not take place in this area.