Efficiency islands are concentric regions on turbo maps that represent the compressor efficiency at any point on the map. So I have read a bunch on how to read compressor maps and why they are important. However, I feel I have missed something.



I see that there is an efficiency island on the map. I assess my goal is to be within the highest efficiency at max engine RPM AND to also calculate a lower engine RPM to see where the turbo falls in regards to efficiency at lower RPMs.



Goal: to draw a line between readings on the compressor map and to keep the line within the highest efficiency island between both points.



Would this goal be accurate?

 

Yes, the more toward the center of the map the better. Too far right and you're pushing the turbo beyond it's limits (this will result in high intake and exhaust temps), too far left and you'll have spool-up issues due to lack of airflow.

 

Don't forget the air temp variable as well. Keeping things centered means the turbo doesn't heat things up as much as if its on the outer edges.