Z20 - Cool running Thermostat - Including housing and seal
This thermostat opens at a lower temperature than standard.
The standard thermostat regulates the coolant temperature to around 90°C, with the occasional jaunt above 100°C! This is good for emissions, but not much else.
This thermostat regulates the coolant temperature to around 80-85°C, which increases detonation resistance due to decreased charge and combustion chamber temperature.
Ideally we like to re-program the fan switching temperatures too, to take in to account the lowered running temperature. This is not strictly necessary though, the fans will just work as standard.