As I understand it too much torque will cause the ECU to retard timing. This is part of the reason a DSG tune is useful - the torque limits are raised. If this is correct the when the ECU retards timing it causes a buildup of boost, correct? Can that lead to compressor surge?
Where could I find the parameters for timing - so I can compare the data log to the acceptable range? Also, what is the difference between specified boost and actual boost in the data log?
Thanks.
Are you saying if your ECU is tuned, that too much torque will cause timing pull without a DSG tune? I don't think that's the case at all. DSG torque limit increases aren't required per just about every tuner out there on stage 1, and is recommended on stage 2 because the torque might actually cause slippage. Nothing about hitting DSG torque limits, because I think that might actually be modified in the ECU tune.
I think I follow your logic about timing, but it's flawed thinking that timing retard will leave you with built up or unused boost. Retarded timing just means that the spark isn't firing at an ideal time for power, but that doesn't change the fact that the engine is just a mechanical air pump. As RPMs rise, the amount of air volume the engine needs increases.
CAM timing on the other hand might effect that, because it does change the amount of time and how much air the engine takes in or spits out.
Compressor surge is caused by too much boost built by the turbo without the engine having a place to put it, which causes air to hit a "wall" on the way to the engine and then hit the compressor wheel, trying to spin it in reverse. Worst case scenario it's going to cause turbo failure, but in reality most if not all tuned turbo cars experience surge. How much and when is a factor of your tune, your turbo, your intake, intercooler, all that.
Specified (AKA Requested) boost = What the ECU wants the turbo to be making
Actual boost = What the ECU is reading at the sensor, what the turbo is actually making