There are 2 temperature ranges to consider. 1. The range the temperature sensor detects and sends a signal to the ECU, in this case the top limit is 120C, so above 120C the signal not longer changes. 2. The range of temps the sensor can operate in and not be damaged. What is the top limit temp and on a 961 head how close to this temp does it get. Its No2 that needs pinning down.