Posted for "George Braly" <gwbraly@gami.com>:

 
 Naf,
 
 There are compressor maps for these compressors.
 
 I have looked at them.  I would be surprised if they were anywhere near the
area of instability delineated on the compressor maps.
 
 The only turbosupercharged piston engine installation  that I have ever heard
of having this problem is the  L IVP aircraft.
 
 Regards,  George


"""
 I would suspect a compressor stall rather than the turbine.  Most of my
 exciting bangs in pure jets have been from the compressor stalling.
"""