Originally Posted by Croustibat

I'd rather know BEFORE running a turbo that i am going into surge or overspin territory, not when i install and break it.
That is the turbo manufacturer job to tell me which efficiency i am going to get, too.

I am not talking about what could limit a turbo application on an engine here, i am talking about the primary function of a turbo compressor. That function is giving airflow at a given pressure at a given efficiency, at a given turbo speed.

And yes, i want to know all that before trial fitting it to any application. Engine dyno is a power result, which may be great, but it does not tell you if the turbo is going to break because it is spinning too fast or surging all the time.