Do I have the right fan for my cooling system needs?

This post will cover all the fan options available for your ride.


Mechanical Fans 
Mechanical fans rely on mechanical energy from the engine in order to operate properly. There are two main types of mechanical fans: clutch fans and flex fans.

Clutch fans are controlled by a thermostat and utilize a clutch to engage or disengage the fan at a specified engine speed or temperature. However, the fan’s clutch never fully disengages—it keeps spinning at about 30 percent of the water pump speed at all times. The clutch also limits how fast the fan can spin and only turns the fan at a fraction of the water pump speed, depending on engine speed and temperature.


Select a Clutch Fan for:

  • Stock or mildly modified engines
  • Best overall cooling ability
  • Applications up to 6,000 rpm

Flex fans don’t use a clutch and therefore operate at 100 percent of water pump speed, making them more efficient than clutch fans. Considered a step up from clutch fans, these fans are typically lighter than clutch fans and often feature blades that flatten out at higher rpms for greater efficiency.


Select a Flex Fan for:

  • Mildly modified engines
  • Good cooling with less drag (than clutch fans) at high rpm
  • Applications up to 8,000 rpm
  • Lightweight design

Mechanical fans, also called belt-driven fans, are an ideal choice for stock or mildly modified street vehicles, but they have some significant performance disadvantages. Mainly, mechanical fans cause parasitic horsepower loss because your engine expends a certain amount of power spinning your fan. This translates into power loss at the rear wheels. That’s why electric fans are typically the number one choice for more highly modified vehicles.


Electric Fans
As the name suggests, electric fans are powered by your vehicle’s electrical system. Although they will place an additional draw on the electrical system, they are a more efficient alternative to mechanical fans and don’t cause the dreaded parasitic horsepower loss.

Here are a few other advantages of electric fans:

  • Consistent cooling—they maintain their airflow at all times
  • Reduced water pump wear
  • Versatility—they can be mounted in front of or behind the radiator
  • Multiple sizes and configurations—they can be found in diameters up to 20 inches and are available with single- and dual-fan setups
  • Fitment—some electric fans have thin profiles so they can fit where belt-driven sometimes can’t
  • Control—some electric fans have an adjustable thermostat while others allow you to operate your fan from your driver’s seat


Select an Electric Fan for:

  • High-horsepower applications
  • Maximum power and fuel economy–no parasitic power loss
  • Enhanced low-rpm cooling
  • Increased water pump life
  • Additional auxiliary cooling

With no parasitic power loss and all the great benefits we mentioned above, electric fans have become the preferred choice for many performance enthusiasts. In a future post, we’ll show you the keys to choosing the right electric fan for your vehicle.

Until then, stay cool.

Author: David Fuller

David Fuller is OnAllCylinders' managing editor. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. He has also partnered with mainstream and trade publications on a wide range of editorial projects. In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing.