let me gues you flew the He111P ?!
the P is engined with DB601 engines. The DB601 as a automatic variable supercharger. There is nothing to shift between low and high blower setting. That the control bar is still there, well......the game is still WIP
The He111H is engined with Jumo211 engines, there the manual shifting between low and high blower is working and needed (in a Heinkel)
The Ju87 should have a setting for an automatic shifting between the two speeds and a setting for low blower only.
In the moment in the game there is a manual shifting between low and high blower - that is wrong.