Flex Fan Vs Clutch Fan: Which One Suits You Better?

As for automotive cooling systems, the two most common fan types are the flex fan vs clutch fan. Both offer different benefits for your vehicle and driving experience.

Deciding which fan is right for your vehicle depends on your engine type, climate, and driving habits. This article will explore their differences and how to use each type.

Keep reading!

Flex Fan Vs Clutch Fan: What Is The Difference?

Flex Fan Vs Clutch Fan

The differences between the two fans come down to power and efficiency. Flex fans offer more power and airflow, while clutch fans focus on efficiency and quieter operation.

Flex FansFan Clutch
Metal flex fans include stainless steel parts with blades made of plastic and riveted to their frame.The fans function based on the clutch technique and the valve’s assistance.
Their blades flattered out based on the RPM.Their thermal operation is the cornerstone of the whole clutch.
The drag energy is needed to power the fan, which is automatically synchronized.The radiator’s heat is utilized to drive off the power. The spring unwinds at a specific temperature, revealing a way inside the chamber.
The chamber allows outside air to enter and cool the engine.
This fan steals more power than other fan models at high RPMs.Also, it creates more noise at low engine RPM.When it comes to speed, RPM is everything for non-thermal fans.The thermal ones are self-connecting because centrifugal force presses the valves together.
The clutch fans’ superior performance can be mainly attributed to their outstanding operation.
When the engine gets too hot, the air from the fan can go through this chamber and cool it down to a tee.
Only one variationMore variations (standard ones with 50-60% of efficiency, heavy-duty ones with 60-70% of efficiency, and super-duty ones with 70-80% of efficiency)

Flex Fan & How It Works

The flex fan is among the most popular aftermarket additions to a modern vehicle. Frames and blades are made of stainless steel, and the blades are either plastic or steel, and they are riveted to their frame.

Their distinct layout is one of their defining features. At the current RPM, their blades get flatter.

It lessens the engine’s friction, which saves power and boosts seamless operation.

How it operates

How well a fan operates is based on its drag and the amount of energy.

With the increased drag, the horsepower is drastically diminished. If you reduce the engine’s horsepower, fuel economy will drop accordingly.

Flex fans may draw significantly more air through the radiator than clutch fans.

This means the engine may be cooled considerably more quickly and efficiently than a conventional fan.

When operating at moderate highway speeds or while idling, these fans provide extra cooling help. Also, at high RPMs, they pull more power than standard fans.

Clutch Fan & How It Works

In between the fan and the water pump shaft is a temperature-controlled coupling known as a regular fan clutch.

The clutch is built so that the fan can run at low speeds while decoupling at higher ones. As such, the entire engine can normally run without being weighed down.

Since it’s a core part of the cooling system, problems with its operation can significantly impact your vehicle’s efficiency. Thus, check the cooling fan or radiator when examining the cooling system.

Still, a clutch fan is often prohibitive. Thus, many customers need help to afford the fan’s initial purchase price.

How it operates

A fan clutch’s operation is straightforward.

Its sole purpose is to operate the fan on/off switch. All the ventilation is there when it’s required most.

The engine automobile speed can be significantly reduced whenever drag is present. This is why operating the clutch reduces engine friction and improves performance.

Most clutches are constructed entirely of silicone-based oil. When the fan disconnects from the motor, all of the oil in the reservoir is safely inside.

A valve opens when the fan is turned on, letting the liquid in. However, this action generates excellent resistance between the housing and the drive plate, which sets the fan in motion.

If the motor transmission is smooth, the engine will retain the fluid more quickly, speeding up the final process.

To release all tension from the fan clutch, the valve closes by itself. Since this procedure is fully automated, no manual clutch activation is required at any point.

Still, over time, the clutch fan can degrade with many symptoms. That’s when you should replace it.

Clutch Fan Vs Flex Fan: Pros & Cons

Flex Fans


  • Compared to a clutch-operated fan, it pulls air flow through its radiator when idling better.
  • Work wonderfully with high-compression-ratio engines, which are more challenging to cool.


  • Rob more horsepower than other fan models at high RPMs.
  • Be particularly noisy at low engine RPMs.

Clutch Fans


  • The operated fan clutch works wonders with an engine-driven fan.
  • Reduce the engine’s drag significantly, entailing the rise of the fuel economy by freeing up horsepower.


  • Be more expensive.

Which Is More Suitable For You?

Clutch Fan

A flex fan and a clutch fan show unique edges that are not interchangeable.

Flex fans are designed to flex with the engine’s RPMs, while a thermostatic clutch fan is best to engage and disengage when the engine reaches a specific temperature.

You can make the best decision for your vehicle by weighing the pros and cons. Radiator fan clutches, or flex fans, are commonly employed to produce the tension and suspension necessary for the engine.

Pick A Thermal Clutch Fan For:

  • Mildly or stock modified systems
  • Optimal cooling ability
  • Applications of 6,000 RPM

Pick A Flex Fan For:

  • Mildly modified systems
  • Sound cooling with low drag (as opposed to clutch fans) at high RPMs
  • Applications of 8,000 RPM
  • Lightweight


Flex Fan Vs Electric Fan: Which Is Better For Modified Vehicles?

Electric fans are usually the better choice for extensively customized automobiles.

Belt-driven fans, or mechanical fans, are perfect for stock or mildly modified road automobiles, yet they have several serious performance drawbacks.

They,  in particular, result in parasitic power loss as your engine must use some power to spin the fan. The result is a reduction in output to the back wheels.

What Is The Difference Between Radiator Fan And Cooling Fan?

They are the same. Due to its proximity in some engine designs, the cooling fan is called a radiator fan.

In other words, you can go for the matched cooling fan with the same functions and size once your current radiator fan can’t turn off or get other flaws.

What Is The Best Mechanical Fan For SBC?

Because you are utilizing a clutch (as you should), the GM 7-blade fan is the most viable approach for your SBC clutch on a mech pump.

How Much HP Does A Mechanical Fan Use?

A single, sizable mechanical fan depends on road speed (engine speed) and can drain as much as 40 hp.


The debate on which fan is the best choice for a car, a flex fan vs clutch fan, has been ongoing for years.

Both provide significant advantages, but only one is the best choice for your vehicle. Thus, you must verify your car models and preferences to get the best flex fan or clutch one on your own.

Share this post with other car owners with the same concerns.

2 thoughts on “Flex Fan Vs Clutch Fan: Which One Suits You Better?”

  1. Good information. I have a Pontiac 428 in my 67 Firebird. Just got the engine professionally rebuilt with quality racing parts even though I will never race it.

    I have a four row aluminum radiator with a big heavy clutch fan. I want to upgrade to something that looks nice and either a clutch or flex fan.

    Any input is appreciated.


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