Fan selection involves several criterions. Things to consider during fan selection are:

  1. Clearance
  2. Performance
  3. Positioning
  4. Horsepower Draw
  5. System Restriction

American Cooling Systems is prepared to help any customer in making a fan selection. Each of these criterions is discussed below:

// Clearance

Generally speaking, American Cooling Systems recommends 1.00 inch minimum clearance forward and behind the fan, to the nearest object. Tip clearance should be as tight as the systems will allow to generate maximum airflow. Relative movement between the fan shroud, radiator and engine impacts tip clearance. If no provisions are provided to hold the movement between the shroud and the fan to a minimum, American Cooling Systems recommends a minimum tip clearance of ¾ inch. A similar relationship exists between the rear of the fan and the engine or other blockage.

// Performance

The amount of cooling that a fan can deliver is determined by the number of blades, projected width (front to back dimension), diameter and RPM. In selecting a fan as a replacement for an existing fan, the intent should be to match the existing fan as closely as possible with the above parameters to provide the same cooling.

// Positioning

The position of the fan relative to the shroud is critical to obtaining maximum airflow from the fan. Improper positioning can account for a reduction in airflow from a fan’s specific airflow chart. Replacement fans should be put in the same position as the original fans. Frequently, fan position can be optimized for maximum cooling system performance. American Cooling Systems can aide in this process by providing instrumentation and assistance to maximize your cooling system’s performance.

// Horsepower Draw

Horsepower draw of various manufacture’s fans differ, depending on efficiency of the fan. In selecting fans for replacement or new applications horsepower draw must be considered. Belt and pulley loads are increased by increased horsepower draw, which will potentially reduce belt life and pulley durability. American Cooling Systems can assist customers with this evaluation.

// System Restriction

The number of fins and rows in the radiator, the number of coolers in series, the proximity of the engine to the fan and many other items effect the system restriction (the ability to pull or push air through the cooling system). System restriction affects the fan airflow capacity by reducing airflow as the system restriction increases. It also affects optimum fan position as described under “Positioning” on the previous page. If a cooling system is being modified, American Cooling Systems recommends that you use our resources to help you optimize the cooling system.

In summary many things affect the fan and cooling system’s ability to cool the engine adequately. Above are some, but not all, of the parameters that can impact a cooling systems design and performance. American Cooling Systems stands ready to help our customers achieve the best cooling capabilities that their vehicles can achieve.