Watercooling may be the fastest growing aspect of PC modding. While you can argue with this viewpoint, you cannot argue with its positive results. In that regard, I have a little heater core mod I did recently that I would like to share with the readers. While this is not a simple project, neither a very complicated one, I think the average modder can pull it off with some patience and the proper equipment.
I designed the shroud to stand off of from the heater core nearly 1” to give the passing air a chance to swirl. All fans big or small have a dead spot directly in their center. If you were to place the fan directly to the shroud two problems are going to arise. First the core is not going to be cooled in this dead zone and second, you're going to restrict air that you are trying to push or pull through the heater core. In my system I am using the push/pull format. The front fan is pushing air across the core while the rear fan is pulling air across the core. This gives a true CFM airflow. Both fans used are Panaflow 120mm 86 CFM.