Larger Exhaust Pipes: Do They Boost Engine Power?

Hello,

At ASZ, the pipes between the turbocharger and the engine are estimated to be about 20% thicker than those in the ALH (not just on the outside, but also on the inside).

But what's the point of it, really?

The ASZ turbocharger forces more air mass into the engine than the ALH, but it doesn't increase the overall volume.
Therefore, the volumetric flow of the compressed air should be identical in both engines (at the same speed in each case), assuming the same valve sizes and valve timing.

Why then are the pipes in the ASZ (presumably referring to a specific system or device) so much thicker?
Is highly compressed air somewhat more viscous, such that the slower flow rate in thicker pipes is intended to prevent excessive pressure losses?

Exactly, Ulf . You've got it. The pressure losses increase quadratically with the volumetric flow rate, and the viscosity of the air increases with pressure and decreasing temperature.

Regards,
Alex.

Aaah, it's always good to have "educated" people in the forum too .

donalexo wrote:

The pressure losses increase quadratically with the volume flow

.
...so that wouldn't be the reason for thicker pipes, but rather:

Quote:

and the viscosity of air increases with pressure and decreases with temperature.

By what percentage would the pressure losses along the charge air path increase if the absolute boost pressure were increased from 1.95 bar to 2.3 bar (assuming the same charge air path)?

Hello,

I'd like to share my extensive, yet superficial, knowledge.

Naturally, an increase in diameter leads to an increase in the volume between the turbocharger and the combustion chamber. This means that the turbocharger takes longer to build up pressure throughout the system, which results in a larger turbo lag.

At what magnification this becomes noticeable, probably no one knows. It is certainly possible to calculate what diameter is 'optimal.' The question remains: Who can do it? I actually have a specific application in the workshop.


Regards,
Stefan.

Exactly, Ulf . You got it. The pressure losses increase quadratically with the volumetric flow rate, and the viscosity of the air increases with pressure and decreasing temperature.

Regards,
Alex

If I remember correctly, the viscosity of gases increases with temperature, unlike liquids, but this effect is relatively small. If the charging pressure is higher at high RPMs in one engine compared to the other, it would result in a higher speed!

Best regards, Schnappi.

schnappi wrote:

If the boost pressure is higher at high RPMs in one engine compared to the other, it would result in a higher speed!

Yes, on the intake side of the turbocharger.

The flow rate, in my opinion, depends only on the engine displacement and speed, between the exhaust manifold and the motor.
A 1.9 engine, in a simplified way, consumes 0.95 liters of volume per revolution, regardless of whether the air it consumes is at a pressure of 1 bar, 2 bar, or 5 bar.

@Stefan Schlünder:
How about your vehicle? With a large turbocharger, low compression ratio, and thick pressure pipes, wouldn't you expect significant turbo lag in your case?

@Stefan Schlünder:
How does it work with your engine? A large turbocharger and LLK (low-temperature coolant) and thick pressure pipes would, in your case, also likely result in a significant turbo lag, right?
There is a small turbo lag, but its effect can almost be avoided by using slipstream in the curves and simply accelerating about 1 second before you need power... I would almost say that this behavior is almost standard, or Unfortunately, there are only poor comparison possibilities, as we went directly from the standard configuration to a complete overhaul.

The pressure pipes have a diameter of 'only' 50mm - it's probably the AFN series.

Regards,
Stefan.

Interesting!
It confirms my suspicion. Without the AGR valve and with modified software, the turbo lag is usually significantly less than with the standard setup, but the other components unfortunately negate that improvement.

I can't find any information about power output or torque anywhere. Are those confidential?

I can't find any information about power or torque output anywhere. Are those confidential?
No, they are not confidential, but rather unknown. We haven't managed to get it on the road yet. It's not possible at the moment, as the Golf is standing there without an engine and axles. But we will make up for it in the spring. I promise. There are also a few more modifications planned... Pessimistically, I would estimate 180 horsepower for the 2004 upgrade stage, with a tendency to increase.

Regards,
Stefan.

One could potentially achieve this using Ulf's DZR system...
/viewtopic.php?t=3939
A motor still requires .

Now, enough about off-topic things .

If the boost pressure is higher at high RPMs in one engine compared to the other, it would result in a higher speed!
Yes, on the intake side of the turbocharger.

The flow rate, in my opinion, depends only on the engine displacement and speed, between the exhaust manifold and the motor.
A 1.9 engine, in a simplified way, consumes 0.95 liters of volume per revolution, regardless of whether the air it consumes is at a pressure of 1 bar, 2 bar, or 5 bar.

Oh yes, a small mistake in my thinking! So, you get a higher pressure loss either through a higher density (delta p = rho/2 * w² * l/d * lambda) or through a higher rotational speed. I don't see any other reasons for it besides flow optimization. The idea that a larger diameter improves heat transfer is nonsense!