Trying to map a turbo. Plz Help

[TravBear2]

This is from http://www.turbobygarrett.com/....html

Now when choosing a BSFC.. What would you all use for a standard 91 octane fuel?

If at 91 oct. it is a .55 BSFC then this is what i am getting...

Lets say 400hp x 12 AFR x BSFC (.55/60) = 44.

MAP = (44 x 639.6 x 590(for temp)) / (.92 x 6500 / 2 x 146.448)

MAP=37.9

37.9 + 2 = 39.9

Compressor inlet pressure at sea level with a loss of 1psi = 13.7

Which creates a pressure ratio of 2.9

With these calculations a KA would surge a gt3582R, 82mm, 56 trim. .70 a/r at 6500 rpm