Spearco Air to Liquid Intercoolers
Spearco offers basic air/liquid intercooler cores that can be combined in a large variety of ways to suit intercooler needs on Roots or Centrifugal superchargers and turbochargers. Refer to the detailed drawings in the drawings section. Air/liquid intercoolers operate by pumping cooled water through the cores either from a front-mounted radiator or heat exchanger, or chilled water produced by circulating the liquid through a container filled with ice, as used in drag racing. Depending on engine size and heat load, we recommend a container that will hold a minimum of 12 pounds of ice. If a front radiator is used, this should be as large as possible since the temperature of the liquid entering the intercooler determines the cooling effectiveness. We recommend a radiator as used on small automobiles with a minimum surface area of at least 260 sq. inches. Radiator technology is preferable rather than oil cooler technology, as these are specifically designed to cool water/glycol. When these intercoolers are used with chilled water, it is possible in some cases, to get charge temperatures below ambient temperature. Therefore remarkable increases in air density and power are possible.
DRAG RACING WITH AIR-TO-LIQUID INTERCOOLERS There are diverse opinions about the advantage of air/liquid intercoolers versus air/air intercoolers in drag racing applications. Some say there is no advantage over air/air and they also say if there is an advantage it is offset by the added weight. The real facts are that other than a small additional weight factor, a proper application of an air/liquid intercooler will increase power more than enough to offset any additional weight, and will always yield superior performance over an air/air unit. Furthermore, the additional weight is sometimes needed for ballast, eliminating this disadvantage. To understand why air/liquid intercoolers are superior for drag racing, consider that the cooling medium in an air/air intercooler is the ambient temperature of the outside air at any given time. If we have an engine running at 30 psi of boost pressure, with an ambient temperature of 90º F, depending on compressor efficiency, the discharge temperature will be approximately 400º F. Assume that you have an air/air intercooler that can give 90% effectiveness at over 100mph and less at lower vehicle speeds. 90% at the above condition will give a temperature out of the intercooler of approximately 120º F, and higher temperature out at lower speeds due to lower cooling and velocity across the surface of the core. Additionally, you are leaving the line with a hot intercooler caused by heating during burn out.