Spritspar-tuning | Posts 16+

I'd be interested to know at which point in the fuel map the fuel-saving tuning is applied.

It really annoys me that boost pressure is built up in 'kickdown' mode to improve braking performance. However, this hinders anticipatory driving and wastes too much energy.
Turning that off will definitely save at least 5%.


Sure, here is the translation of the text from German to English:

'MFG' stands for 'Mit freundlichen Grüßen,' which translates to 'Sincerely' or 'Best regards' in English. It is a common way to end a formal letter or email.

Boost pressure buildup does not destroy any energy.

Oops... you seem to have made a slight mistake. What energy source does the turbocharger use for its operation? Doesn't a highly compressing diesel engine always have significantly higher motor braking force in overrun compared to a gasoline engine? This is due to compression. Where is the turbocharger located? If no fuel is injected and it generates minimal load, then this is unfortunately inherent to the principle. You can delete all the maps in that case. Even a diesel engine without any electronics does this...

@matthiasTDI96

Can you please explain that to me in more detail? I don't understand your answer.

Sure, I can. It refers to the post before yours. In short, a turbocharger in a diesel engine will always be able to build up some boost pressure (at least minimally) because energy is available. This also applies to gasoline engines, although to a lesser extent. The compression process creates an increase in temperature (energy), which can be converted back into power by the turbine. You can often hear this clearly during cruise mode with fresh oil and an open window, and it can be read on a good lambda sensor.

That's all I meant.

matthiasTDI96 wrote:

Yes, certainly, if you like.

Hi there,

Flightmaster probably meant that in reference to unnecessary braking power of the engine and letting the car coast predictively. I'd also be interested in knowing how much kW such an engine produces with maximum VNT control at around 2000 rpm, and how much without it.

It would certainly be interesting to know whether, before the town of xyz, one can only coast for 300 meters or perhaps 400 meters because the motor brakes less aggressively.

Hello everyone,

without me knowing any more details, but...

I recently read somewhere that the turbocharger in a TDI engine is actively controlled during coasting to generate more braking force.

In my ALH engine, the turbo boost pressure is definitely higher when accelerating than when idling.
If the valve were fully open, it shouldn't actually build up much pressure.

The higher the turbocharger pressure, the greater the force required for compression, and consequently, the stronger the braking effect on the engine.

Or am I misunderstanding something?

matthiasTDI96 wrote:

The compression process creates a temperature increase (energy) that

can be converted back into power in the turbine.

flightmaster wrote:

During decompression during the downward movement of the piston, an adiabatic cooling occurs to the initial temperature.

The higher the boost pressure, the greater the force required for compression, and consequently, the greater the braking effect on the engine.

Or am I misunderstanding something???} I think not. In fact, you need more pressure for the compression process with a larger cylinder filling volume. However, as I mentioned above, there is a recovery of energy during the downward movement. So it doesn't matter whether boost pressure is built up or not.

The turbocharger is kept spinning by the loader to minimize turbo lag.

Hello Uwe,

What you're writing isn't entirely correct. While it might not be as relevant in a passenger car engine, in trucks, the VTG (Variable Turbine Geometry) is often used to its maximum extent to significantly increase the engine braking effect.

You are correct about the compression/expansion; it approaches zero. However, you need to consider the back pressure in the exhaust system (which increases the pumping work). The variable geometry turbocharger (VTG) is essentially used as an exhaust valve (found in older truck diesel engines), and it even amplifies this effect by generating higher boost pressure, etc. (creating a cycle). The large volumes of air being pumped also significantly increase the braking force.
Unfortunately, I don't have specific figures. I remember listening to a presentation by Iveco about it years ago, and I recall that the braking performance was really impressive.

Best regards,
Albrecht

With an engine displacement of 16 liters or less, and a lower gear with the corresponding RPM, there is indeed a significant braking effect due to exhaust back pressure.

"In my 1.9L car, I usually ride in the highest gear, which results in engine speeds below 2,000 RPM even when driving on country roads. With this, the 6-speed transmission allows for a speed of at least 120 km/h. On the highway, the other driving resistances increase quadratically, while the braking torque of the engine becomes less relevant."

At low engine speeds, even with the variable turbine geometry (VTG) closed, there is negligible boost pressure buildup, which means the turbocharger can only absorb a small amount of braking force.

That may be correct to a certain extent. However, we are quite familiar with the fact that the gas flow during boost operation, even under forced conditions, exhibits a temperature change. Although it is very small, that is true. I was not talking about extremely high pressure levels, but rather minimal ones. It is clear that exhaust gas recirculation and variable turbine geometry have an influence.

matthiasTDI96 wrote:

We are quite familiar with the fact that the airflow during boost operation, even in forced boost, exhibits a temperature change.

That's correct. It comes out cooler at the back thanks to the intercooler than it goes in at the front.

Eine adiabatische Erwärmung findet nur temporär während der Verweildauer im Motor oder genauer ab dem Turbolader statt. Am Auspuff herrschen wieder die gleichen Druckverhältnisse wie vor dem Turbo. Also gibts keine adiabatische Erwärmung. KEINE!

All that remains is the heat absorbed during its stay in the engine compartment through contact with the hot surroundings. And we already lost that heat at the intercooler before it reached the engine.

Even the desired boost pressure is hardly available at less than 2,000 RPM and under full load. Furthermore, if the gases are not yet undergoing combustion, it becomes extremely difficult to build up any boost pressure due to the lack of exhaust gas.

I am convinced that the variable geometry turbine (VTG) is completely closed during acceleration to ensure faster throttle response.

Even desired boost pressure is only available at <2,000 RPM and hardly accessible under full load.

Hello Uwe,
I'm a little lost in your discussion.
It's about VTG loaders, right?
Why is there supposedly very little load dump (LD) present at engine speeds below 2000 rpm and under full load conditions?
I reach my maximum (series) load at approximately 1800 rpm. That's where I achieve the desired 1995 hPa. Even at 1500 rpm, I get a boost pressure of 0.6 to 0.7 bar. I no longer consider that barely any load.
Even a bypass loader reaches its maximum load density (LD) below 2000 rpm. How else can I achieve maximum torque if the maximum load density isn't reached?

I am convinced that the VTG (Variable Turbine Geometry) is completely closed during acceleration to ensure faster throttle response.

This is one of the two reasons why the VTG (Variable Turbine Geometry) system is closed in boost mode. The second reason is to assist with engine braking during boost. This is advertised effectively on the manufacturers' websites for VTG chargers.
The achievable load densities are also not that low. At 2500 rpm, I'm getting about 0.5 bar of overpressure when the thrust is cut off.

The VTG is essentially used as an exhaust flap.
That's right.

The topic is already settled; we've discussed this all before.
What is not yet clearly defined:
Is the laser diode controlled or even regulated in terms of its power output?

Best regards, Jochen.

Quote:

Is the LD controlled or even regulated in its thrust?

Jochen_145 wrote:

Is the LD controlled or even regulated in its thrust?

Hi Jochen,

IMO, it's being controlled: There are parameters like fuel quantity and engine speed within the LD control software that appear as threshold settings. It seems that below 1200 RPM, the system is always in a controlled mode, while above 1200 RPM, it switches to a regulated mode when more than 13 mg of fuel is injected.
This amount decreases with increasing speed until it reaches 6 mg.

Hello, I watched a report on the WDR (a German TV channel) about a Swiss oil and lubricant manufacturer that produces lubricants from plant oils.

These oils are supposed to be significantly better and more durable than lubricants made from fossil fuels.
These plant-based oils have likely been used in the aerospace industry for some time.

It is claimed that using these plant-based oils can reduce fuel consumption by up to 0.5 liters per 100 kilometers.

Furthermore, they offer an additive that allows you to run your engine on plant-based oil without modifying it.

http://www.multimiles.ch


http://www.multimiles.ch/tests.htm#



Sven.