Repeating an endless droning about Saab's turbo engine management. Having looked at Saab's Tronic-5 turbo engine management system, this is what is required to produce a reliable turbo engine. While the engine internals must be up to the torque demands of a turbo engine, making a reliable turbo engine at any reasonable boost is NOT simple.
From fuel delivery, detonation sensing and control, ignition control, turbo boost sensing and control, temperature monitoring and corrections for compressed air_ambient air temperature_engine coolant and a long list of other engine management demands. Once can upgrade the engine internals, that alone will not produce a completely reliable turbo engine, proper engine management is a major aspect of turbo engine reliability and function.
About the Saab Trionic-5, This became the basis for nearly every production and motorsport turbo engine produced.
Read and look over how this turbo engine management system works. This will give an idea of what is required to make a reliable turbo engine.. It's a LOT more than fueling correction or ignition control.
http://4saab.com/T5Suite/Trionic5.pdf
Piston failures in turbo engine are often the result of detonation, stronger piston, con-rod and such alone will NOT cure the root problem of poor turbo engine management.
Oh, by the way, Fiat Turbo Uno engine block is different than the normally aspirated engine block which has Siamesed bores for rigidity, turbo block does not for enhanced cooling. This is why the turbo blocks have smaller bores than the non-turbo blocks among other differences.
Bernice