I think max temperature depends a lot from what country you are coming. Down here we don't have enought money to put a lot of petrol in our cars so we put it just enought to get to our favourite pub and drive back home. Now the temperature depends how far is your pub but I would guess for our 2cv's max temperature is about 130-140. Sometimes we want to feel really wild so we press the throttle to the floor for a few minutes so that bring our engines to about 170-180 degres.

My advice would be: try to contact manufacturers of duck tape so that can give you a starting point. It does a really great job for some time when you get a holle in exhaust.

@Bart still you didn't tell why you need it!! May be we can help then.....

Cheers Ante...
I like your way of thinking!