Radiator These all aluminum, downflow radiators feature large tubes for superior cooling over stock style radiators. They are 100% welded construction and include a built-in transmission cooler. This radiator has both the upper and lower necks on the passenger side. Learn more about how radiators work and selecting the proper radiator for your vehicle by reading our tech article. Radiator Cooling Performance. Radiator Cap A must have when racing! High pressure cap for radiators raises boiling point of water. Made of High quality steel with zinc plating. Rated for 20 PSI. Learn more about cooling systems, how to choose the proper pressure cap, and how they work by reading our tech article. Cooling System Principles.