My understanding (which cant be that wrong regarding my calcs):
The term "ungedrosselt" (="unthrottled") refers to the point where the opening area of the Throttleblade does not limit the gas-exchange of the engine anymore. But from a pure "mechanical" point of view ( = 100% rl) and has nothing to do with the boost you are aiming at.
The calculation for a 1.8T Engine for example:
Engine Displacement = 1781cc
nCyl = Number of Cyl = 4
Vcyl = Volume per Cyl: 445cc
rhoL = air density: 1.2 kg/m³ = 0.0000012 kg/cm³
using the equation:
mAir[kg/h] = Vcyl[cc]*rpm[1/min]*rhoL[kg/cc]*60*nCyl delivers this theoretical 100%rl. All you have to do now is multiply it by 0.95 taking PSPVDKUG into account.
then you have to calculate the corresponding throttle value to these mass air flows using KFWDKMSN. I also used excel for this.
The calculated Values vs. Values out of the original File of WDKUGDN:
As you can see the fault is around 1% between 2000 and 5000 rpm. The error @ 1000 rpm is 3 degree Throttle Value and @ 6000 rpm its 2 degree which seems to be ok for my definition....
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"The calculated Values vs. Values out of the original File of WDKUGDN:". I wanted to cross check my revised angles against what the result was here. Let me ask my question in another way, if msdk > mshfm at a given RPM, would you expect the wdkugn z values to increase or decrease? I have calculated my kg/hr using the air density at my spring pressure of 0.8bar and the kg/hr gives me values that are lower than the ORI. Anyone who can verify whether this feels right. This is for gt28 and external wastegate with 0.8bar spring
