Charge pressure regulation for VTG turbochargers

Hello everyone,

Inspired by yomans' question, I re-analyzed one of my experiments and created a new diagram that clearly shows the behavior of the VTG (Variable Turbine Geometry) control system during full-throttle acceleration from third gear to the maximum engine speed.

This applies to ASV engines, but it can certainly be applied to other VTG engines as well.

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For scaling purposes, I used "parts per thousand" instead of the percentages that VAG-COM displays, so I multiplied the values by 10. Small values (the smallest was 24.7%) indicate that the guide vanes are in the position for maximum turbo speed, while large values (the maximum was 94.4%) indicate that they are doing the opposite, meaning the turbocharger is being throttled. The latter is very noticeable when trying to reach the proximity of the cut-off speed.

It's also good to see how the regulation reduces the VTG (variable turbine geometry) angle as the engine speed increases, while the boost pressure remains consistently stable.

I think (this came to mind when I saw Yomans post) that this diagram can also be used for analyzing data from Block 11 measurements, because the measurement conditions there (around 3000 RPM, full throttle for at least 3 seconds) are very well represented in the middle of the diagram.

I didn't analyze the actual second value from block 11 (target boost pressure) in detail. Those who are interested can investigate it further, but I don't find it particularly exciting because it comes from the lookup table and doesn't depend on the "condition" of the engine components – experts may correct me if I'm wrong.

Best regards,

Jan.

P.S.: I hope no one feels annoyed or bothered by my diagrams. If you do, please let me know!http://www.informatik.hu-berlin.de/~richling/tmp/ladedruck.png{MARKER}