Tom, thank you very much.
This turbo is fitted to a 40 ton bulldozer (International TD25C), it has proved almost impossible to find information on this turbo.
The engine was available in several different power ratings and we suspect it has the turbo from the higher rated engine.
Uprating the engine to suit is not really an option as we'd like to preserve the driveline.
Is this the book you mentioned?
http://www.racecar-engineering.com/r...-k-miller.html
Do you know of a good source for these turbo parts? Location doesn't matter much as long as the price is reasonable and they are willing to ship internationally.