I have been looking for a BSFC chart for a C-code 82 GM 6.2ltr diesel for some time.
I found this
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA349754
Better than absolutely nothing, sadly they only consider WOT but it still is quite interesting, fuel consumption per unit of power stays quite flat for an NA diesel
I would be most interested in the NON-wot values.