What does the engine Precooler do KSP?
The precooler is in principle a slightly better heat conductor than other (non-radiator) parts with double the heatConductivity and it also has superior heat emission which allows it to act as a passive radiator and wick away heat more effectively, this effect is not limited to engines nor to atmospheric use.
What does a pre cooler do?
A type of heat exchanger in the aircraft air-conditioning system that is like a radiator. The air to be cooled passes around the cores through which the ram air passes