Your going about this backwards. First off, factory pumps wern't designed to run at 4500+ rpm's. They are the most efficient at low speeds. Performance/race pumps are actully built to slow circulation at high r's. Slower is better, more dwell time for the coolant to pick up heat from the engine and more time in the radiator to dissapate it. Radiator capacity, fan diameter and cfm are the determining factors for cool down speed. Also, depending on the thermostat used, it will become a restriction the cooler it gets. What are your expectations? if your hot lapping, the only way to cool quickly is to drain and refill. Speaking of electric fans, many will run both ways depending on how the're wired. Make sure it's turning in the proper direction.
