I5 GT Turbos 2871 / 3071 / 3076 / 3082 / 3582

[Ross]

The 72 percent efficiency island goes up to 2.6 bar so i would run it up to that pressure at redline, granted it drops down to 65 percent at 3 bar.

Just the same as the efficiency on the 35R map is 72 percent up to 2.2 bar.

As per billman's post, that's not healthy for the turbo. The graph combines 3 factors - efficiency, pressure AND flow in lb/min. You have to take those into effect, 2.6bar at the redline on the I5 will be WAY above the compressor's max flow rate and the turbo will be dead pretty quickly if you overspin it in an attempt to do so. I'd run the GT3071R, calculating from that map, at circa. 1.7bar at the redline.

[EspenW]

i was referring to the actual number if the losses were added to it.Not the procedure from which it was made from.
I just think that a rough calculation that adding 100hp to a whp number we get from any type of dyno for a 4x4 car is completelly wrong.

Absolutely agreed. WHP will vary drastically between dynos.
For example the R35 Nissan GTR:
405whp on Dyno Dynamics RR
410whp on Mustang RR
430whp on Dynojet RR
458whp on Dastek RR
460whp on Dynapack hub dyno

Dynos are tools for measuring before/after gains, not calibrated instruments for measuring absolute values.