A picture tells a thousand words; I think this is what we're all talking about:
What worries me is that it's likely the figures we see occasionally (735°C in my case) are actually occurring all the time, but it's only when I allow the thermocouple to reach that temperature that they're evident. In the example above, the turbo is above the 'danger' line for 12 seconds. Ok, all the numbers are complete guesswork but the principle's sound. In my oh-so humble opinion, the t/c can't react too fast, even if the display's unreadable. If it starts with a 7, back off. If you can't read the 'hundreds' column, back off quick!.
JB
All graphs copyright TeamNutter. No diesel was burned in the production of this fiction.