The purpose behind a Spal H.O. fan is to improve airflow in high static pressure circumstances. It is important for air to flow at a high rate to regulate the temperature of your car cooling system. This includes the radiator, A/C condenser, and the oil cooling unit. Spal H.O. fans were developed for vehicle environments where high static pressure becomes an issue. Initially a presence in heavy duty trucks and vehicles with diesel engines, they have also become adopted by performance car enthusiasts. Drivers who run racing models employ Spal H.O. fans for a strong, effective method of engine bay cooling.
Like most Spal products, there are different sizes available. High output performance fans are available in 11", 12", and 16". The three sizes are the most common for engine compartment applications. If you look inside of a racecar, often you will find a Spal 16" puller fan. This size is preferred because the amount of heat and pressure generated under the hood strongly inhibits air through the core. Crew chiefs will install a Spal 16" puller fan behind the radiator and if space is adequate, they will point another one at the oil cooler. NASCAR drivers use a setup very similar to this. A Spal 16" puller fan with a high output motor is favored because of its power and long-life motor.
Material is very important. High output performance fans have nylon blades that are filled with glass. The surface of the blades is smooth which helps them rotate smoother and resist dust. The glass filling is there so that the high output performance fans demonstrate low vibration and consistent balance. Another crucial aspect is the motor protection. A motor exposed to heat or dust can lead to dysfunction. Spal seals each automotive radiator fan motor tightly so they do not become damaged due to the elements of the engine compartment.
Airflow rating is how to tell the overall power of a high output performance fan. Since there are three main sizes Spal offers, there are three different ratings figures. 11" models offer 1,604 CFM; 12", 1,870 CFM; and 16" options showcase 1,953 CFM. The best part is that all of these Spal fans are able to maintain their CFM throughout virtually all internal automotive conditions.