Then it was a simple task of adding the pressure drop according to the real flow numbers I have and running the simulation for a number of different valve lift values. The results are as follows:
As you can see, the predicted flow numbers correlate reasonably well with the measured values. There is around 7% difference in the region of interest, which considering the CAD model has been cobbled together from photos and limited dimensional data available on the web, I think is none too shabby. I will only be using the model to compare different options rather than looking at absolute values, so I believe this is a reasonable starting point.