can you add motor efficiency to standard blocks?

I have been trying to match up some data for a squirrel cage induction motor to a model of the same system. It is basically a diesel engine feeding power to an asynchronous machine. However, after a lot of tuning and fiddling i cannot get the transient components to match up, the real data always shows a much larger current spike than my model. I have used the real values for the actual machine as far as possible however i see a 40% error in the initial current spike in the system.

I am wondering if this is done to the efficiency of the model against the actual efficiency in the real machine. Has anyone put efficiency into the standard asynchronous block or know how to do it. Or any ideas about what else i could look at for an answer?

Best

Chris