[AT] Tractor Diesel Engine question - non-antique

[Grant Brians]

I am hoping someone on the list (perhaps Mike Sloane?) can help me on
understanding something on recent design Diesel engines. Every tractor and
truck manufacturer of any size now has multiple versions of their diesel
engines with different Horsepower ratings and Torque rating curves. Clearly
they are varying settings in the controls of the fuel systems and some
versions might have a turbocharger or intercooling. What I am trying to
figure out is when there is an engine that is NOT electronically controlled
(there are still some), what SAFE changes could an owner make to settings to
take advantage of the inherent capabilities of these units.
     In particular, I have Perkins and New Holland engines that fit into
these categories. In one case the nominal rating of the tractor is 78HP PTO,
but my unit was dyno tested when I bought it with 93HP from the factory and
others have "adjusted" these engines to get over 100HP PTO. I am also
looking at possible acquisition of another tactor that has tractors in the
same "family" using the same engine but with different adjustments that are
as much as 45% higher horsepower. These variants of the engine are all
Tubocharged and Intercooled, so can a skilled and knowledgeable diesel
mechanic change the settings?
     Inquisitive people would like to know! I am not saying that I would
make any of these changes, but I know that in the past when I have converted
OLD engines to better components that their performance has materially
improved, sometimes yielding 25% more work.... Also, at times the fuel
economy has gone up, but I know that would not happen in these newer
engines. I do know this would void the no longer applicable warrantee on
these engines if one were to perform the changes, but I still have a burning
curiousity.
           Grant Brians