Turbo selection

Well, It looks like it is back to turbo selection time for me. Hence I have pulled out some of my old 3sgte airflow predictions on turbo compressor maps.

I will try and formalise this over time so if anyone has any comments on engine VE or the basic method I used for airflow predictions please feel free to comment. If there are any particular turbos that I have missed let em know and I will try and add to the list.

There are some quite major items I have previously ignored in order to get a rough idea:- 1) Compressor efficiencies - these vary for each turbo - between 75% to 80% and will effect charge temps. 2) Turbine side efficiency and matching - trying to cross reference between the shaft speeds etc started to make my head hurt. 3) Engien VE varies over RPM/Boost - 4) Intercooling efficiency

I have seen some really nice calc sheets about that try and take into account most of the above but unfortunately I have never found one that actually produces realistic figures!

In order to understand a compressor map this diagram is posted by Garrett:-

This graph comes from an MR2 forum and provides some guidance on what figures are actually achieved on a Dyno Dynamics rolling road:-