Originally Posted by Corse-R

A safe temp range? under what kind of assumption? each engine responds different to carb adjustment and handles different the temps, one engine at 130ºC could be giving the ghost and the same model, still have some margin... what kind of margin?

The only one will tell you how's running your engine is how sounds on the track, the smoke and of course, how idles entering for a refuel. This is why give you real data, not a crude temperature number that doesn't means nothing.

One crude example: Two engines of the same manufacturer (Sirio), the same model (.12 STi). One bough in April and the other bought at the end of July. The one bought in April loves to go at 150ºC and runs strong and idles great. The other, anything over 140ºC is hurting the performance.

All two runs strong. But they want different temps, which one should I trust? the one who likes to go at 150 or the 140ºC one? Tunning by temp as a rule carved in stone is a sillyness and somewhat stupid. Know your engine and forget the temp.