Chill out your engines

Jan. 1, 2020

A factory cooling system normally does a pretty good job maintaining the right engine temperature, as long as the vehicle remains unmodified or doesn't handle heavy loads. Add some performance upgrades or use it in heavy-duty applications, however, a

Steve Temple

Don't let your customers get overheated about controlling engine temps.

Custom Bay engine coolants cooling engines overheating engines engine fans SPAL USA SPAL fans performance fans A factory cooling system normally does a pretty good job maintaining the right engine temperature, as long as the vehicle remains unmodified or doesn't handle heavy loads. Add some performance upgrades or use it in heavy-duty applications, however, and the stock setup just might get overloaded. As proof, Heath Langenfeld of SPAL USA, an electric fan manufacturer, says that solving the problem of an overheated hot rod is one of the company's most common customer inquiries.

Excess heat wreaks havoc on engine components and, if left unchecked, can destroy an engine.

There are a number of different ways to reduce heat, but the most effective includes increasing the airflow through the radiator or the cooling capacity with a larger or more efficient radiator. Yet another approach is to tightly control when the engine needs to be cooled.

Most modern vehicles employ electric fans to help draw cool ambient air through the radiator core. Because each fan has a predetermined airflow rating given the voltage supplied, the only way to increase the amount of airflow being drawn through the radiator is either to increase the rpm of the fans or to employ a more efficiently designed fan.

That doesn't mean, however, that you should just install a pair of high-efficiency fans. They might actually cool the engine too much, especially if activated by a toggle switch, resulting in higher emissions and less engine performance.

Cooling fans ideally should operate only when the engine is approaching the limit of normal operating temperature. Traditionally, a thermo switch mounted in the radiator or intake manifold triggers a relay to activate the fans at a predetermined temperature, but that method lacks the variability that can improve cooling efficiency and prolong fan life.

In contrast, SPAL's engineers have developed a product that precisely controls the speed of electric cooling fans. The PWM V3 programmable fan controller allows the user to variably adjust the speed of the cooling fan(s) based on the engine temperature. This unit only requires the user to program a high- and low-temperature setting.

When the engine reaches the low-temperature setting, the PWM V3 operates the primary fan at 50 percent of its maximum speed. As engine speed increases, the unit adjusts the speed of the fan proportionately to provide proper cooling as the engine needs it, until it reaches maximum operating temperature where the fan will operate at 100 percent.

The PWM V3 also is capable of operating a second fan (with the use of a relay harness), so it can be activated once the primary fan has reached full speed. Another useful feature is the ability to operate the fans at 100 percent when the air conditioning system is engaged.

Shown here is the installation of a SPAL PWM V3 and Dual 11-inch Fan into an AMC Javelin that is in the process of being restored.

Steve Temple is a freelance technical writer and photographer with more than 25 years' experience. He has served as director of sales and marketing for Shelby American and as online editor for major magazines such as Hot Rod, Car Craft and Rod & Custom.