CBR's surge tank reduces the air pockets in your vehicle's cooling system to prevent high RPM water pump cavitation. By mounting the the surge tank as the highest point in your cooling system, and connecting all high points to the tank with one line connected to the inlet of your radiator, the system creates a vacuum that collects the air bubbles in your cooling system. This air is then purged to an overflow tank. This allows your cooling system to be continually bled even at high engine RPMs. Recommended to use an overflow tank with the surge tank.