During the early '70s, copper/brass radiators were used worldwide due to their superior ability to conduct heat, but weighed three times that of aluminum radiators, were expensive to manufacture, and experienced high failure rates due to corrosion and stress fractures. Aluminum radiators made their way into automobiles during the '80s, as OEMs embraced the idea of a lighter, more cost-effective design that lasted two to four times longer than copper/brass radiators. Today, the OEM standard radiator-using an aluminum core with plastic tanks-can be found in 99 percent of cars driven on the highway. Follow along as we showcase the ins-and-outs of radiators as we cover what to look for and avoid when addressing your cooling system.
Single-Pass Vs. Dual Pass Radiators
There's been much debate into the theories and logic behind dual-pass/double-pass radiators and their benefits over the more commonly used single-pass system. The Koyo dual-pass radiator (pictured) uses their N-FLO technology that welds two partitions half-way through the radiator core, thus splitting the tank into separate chambers. The "N"-shaped water flow pattern is designed to improve radiator efficiency by passing the fluid over the first half of the radiator and then the second half, allowing the core to dissipate heat twice, while maintaining the coolant in the radiator up to three times longer, offering improved cooling. Koyo representative Scott Oshiro explains, "Dual-pass radiators like the N-FLO were designed specifically for known applications where cooling was an issue, such as with drift cars." In cars being pitched sideways down a track, using a dual-pass radiator allows the radiator to cool efficiently, even when ambient air isn't being forced directly into it at all times. Unless a car suffers from previous overheating issues, all three radiator manufactures we contacted recommended using the traditional down-flow or cross-flow single-pass radiator, which presents all the tubes with the highest possible water temperature at once. Dual-pass radiators work efficiently at high speeds in certain race-prepped systems, but do so at a cost of increased load on an engine's water pump, and inefficient low-speed cooling capacity, which can raise pressure and temperature to higher-than-desired levels.