[Ziggster]

A six bladed fan will definitely move more air. It will take more horsepower to do so, and will likely make more noise depending on its fan blade shape. The bigger, more powerful the engine, the more the reject heat will be. So, yes, in theory, you will need a "larger" cooling system to deal with the delta in reject heat. That typically would require more water flow, a larger heat exchanger, and more airflow. However, you would start with the one variable that was your limiting factor in the first place