DZR Test: Boundary Conditions & Requirements

Hello professionals!
When you look at the Excel table for the DZR test, it always calculates based on the maximum power or the maximum torque.

This means that, in order to properly conduct the test, you should accelerate fully from idle speed whenever possible, so that you can achieve the maximum torque within the measurement range of 2000 to 4000 RPM.
When accelerating in third gear, the turbocharger pressure will likely lag slightly behind the engine speed, which means that the static power and torque calculation values might not be entirely accurate ( Sorry Ulf, this is just constructive criticism to potentially improve your program!).

Do you use VAG-COM to measure times, or do you have a dedicated co-driver with a stopwatch who can closely monitor the tachometer needle when it passes the 2000 and 4000 RPM marks?

VAG-COM hat zwar relativ niedrige Samplingfrequenzen, man hat aber bei einer graphischen Auswertung sehr schön die Möglichkeit der Interpolation, um die exakten Zeiten zu bestimmen. PExperiences with Raxis?

Regards,
Alex.

Hi,

You actually start accelerating from idle to ensure that you have full boost pressure at 2000 RPM. You can manually measure it, but I find it to be quite inaccurate, so I prefer using VAG-COM and interpolations.

Check this out:

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.

That was the thread about it back then, and I also posted a lot of diagrams about acceleration and boost pressure there.

Best regards,

Jan.

donalexo wrote:

Then, in those calculations, the maximum power or maximum torque is always assumed. This means that, for conducting the test, one should, if possible, fully accelerate from idle speed. . . When accelerating in third gear, the turbocharger pressure will likely lag slightly behind the engine speed, so the static power and torque calculation values may not be entirely accurate ( Sorry Ulf, this is just constructive criticism to potentially improve your program!

).

Hi Alex,

I don't have a problem with criticism, as long as it is genuinely meant to be constructive .

But let me ask a counter-question: with which reduced torque value would you "prefer" to calculate?
IMO, due to variations in individual cases (e.g., setting of the VTG, etc.), such large uncertainties would be introduced into the calculation that one could probably only use them as a rough estimation tool.

It's more reliable to ensure that the "static" torque is maximized – meaning full throttle from around 1300 rpm.

Quote:

Do you use VAG-COM to stop the times, or do you have a dedicated co-driver with a stopwatch who can closely monitor the tachometer needle when it exceeds the 2000 and 4000 marks?

I myself act as the co-driver with the stopwatch , of course, only when the track is clear of other cars, and when it's "safe" to take your eyes off the road for the moments around 2000 and 4000 rpm on the tachometer.
Because a passenger always looks at the tachometer at an angle --> parallax error or something like that .

Hello Ulf!

Quote:

But let me ask a counter-question: with which reduced torque would you "prefer" to calculate? IMO, due to variations in individual cases (e.g., setting of the VTG, etc.), such large uncertainties would be introduced into the calculation that one could probably only use them as a rough estimation tool.

I thought it might be possible to log the actual injection amounts during a test drive using VAG-COM.
When the injection quantity corresponds to the torque limit value, then the calculation matches the "static" full-load torque.
However, if there are any deviations, one could calculate the ratio between the actual injection quantity and the target injection quantity (torque limitation) and proportionally reduce the torque accordingly.

It might require a bit more effort, but it should provide more accurate results. What do you think of this method?

Regards,
Alex.

donalexo wrote:

I thought that it might be possible to log the actual injection amounts during the test drive using VAG-COM. When the injection quantity corresponds to the value of the torque limit, then the calculation matches the "static" full-load torque. However, if there are any deviations, one could calculate the ratio between the actual injection quantity and the target injection quantity (torque limitation) and proportionally reduce the torque accordingly. It might involve a bit more effort, but it should provide more accurate results. What do you think of this method?

Hi Alex,

Generally, the idea is probably correct, but to be completely accurate, a correction based on efficiency would be needed – the efficiency is at its highest with the maximum injection volume.
If one could use a "generalized calculation" (e.g., the ratio of actual injection amount to torque limitation raised to the power of 1.2, or something similar), it could potentially represent a theoretical improvement in the torque-speed characteristic.

"In my opinion, this probably won't lead to any fundamentally new insights, because the current version already contains a lot of detailed information and, as a calculated performance value (based on data from several forum vehicles), it provides a performance level that is quite typical for TDI engines."

If the dyno test (DZR-Test) showed that a significant amount of horsepower was being lost (as you assumed), then the calculated power output would have to be adjusted downwards accordingly.

Hi!

Are you absolutely sure that the dynamic approach delivers significantly less?
I can imagine that with a vacuum cleaner that has some kind of vibration effect. But with a TDI engine, if you start at a low RPM to avoid turbo lag, then there's an overshoot, and then the boost pressure is kept constant, right?
'I'm not sure why a significantly higher torque would occur in a static operation. I seem to recall hearing about dynamic torque increases compared to static torque during acceleration, but I don't remember which motor that was.'

So, I think that with our TDIs, any dynamic power reduction should definitely disappear within the DZR (Dynamic Zero-Emission Range) inaccuracy.

All the TDIs I tested were actually very close to their rated power output. Perhaps VW doesn't ship the extra power to Austria (due to stricter regulations or something like that).

Best regards,
Ernst.