How to Choose the Best Electric Radiator Fan | Size & Setup Guide

Which one should you use in your build? When it comes to a puller fan vs pusher fan, the puller fan is the preferred installation method (what you’ll see in most OEM applications today) since pulling the air through the radiator core is more efficient and provides less turbulence through the core. From daily drivers to performance builds, a puller fan is the best option providing there is enough engine bay clearance for installation.

For installations where the engine bay is tight on space and a puller fan cannot be comfortably used, pusher fans are an option. Pusher fans can be used in place of puller fans where there isn’t room to run a puller fan, such as in an engine swap situation, or they can be used to supplement puller fans or aid in additional airflow for the air conditioning condenser or oil cooler (essentially anything that may be mounted in front of the radiator core’s air path). So, as you can see, when it comes to puller vs pusher fan the main issue will usually be mounting space consideration.

Speaking of using a pusher or puller radiator fan we really need to go over some common misconceptions about their uses as well. Probably the number one comment we hear is "You can just flip the fan to change direction." This could not be further from the truth. You see, a fan is designed to move airflow in a specific direction. This includes the blade angle, motor direction, and more. Just flipping the fan from one side of the radiator to the other and swapping the power and ground wires to spin the fan the opposite way is asking for problems. Another one we see a lot is the statement that pusher fans are just as efficient as puller fans. With all considerations the same (diameter, number of blades, blade angle, etc.) a puller fan will usually be more efficient moving air through the radiator core. Lastly, is the old more fans equal more cooling mantra. This is only true when airflow is optimized (two puller fans with a shroud, or one pusher and one puller, but on opposite sides of the core so they’re not fighting each other).

What about installation tips, do they differ when it comes to puller vs pusher fan for questions like how far should electric fan be from radiator core? When mounting a puller or pusher fan you’ll want the fan body to be as close as possible to the core surface with a rubber seal on the perimeter of the fan at a minimum and preferably installed using a universal electric fan shroud to help pull air through the entire core surface area. Verify proper airflow of the fan you are using. Most electric radiator fans have arrows molded into the fan housing showing direction of the fan’s rotation and airflow direction through the fan. If using a pusher fan and a shroud isn’t possible (interference from the hood latch brace for example) use heavy duty rubber to seal the radiator to the core support to maximize all airflow through the radiator so that no air can flow around the radiator. For puller installations confirm there is at least 3/8-inch clearance between the fan body and any accessory drive pulleys/belts. This is how to install electric fan to radiator tips for 99 percent of the applications out there, but there will always be that one build that requires a custom fabricated shroud or other necessity, so be ready if that’s your build case.

Single Fan Setup

Advantages:

• Simplicity: Fewer components mean easier installation with less wiring and only need a single relay.
• Space Saving: Great for tight engine bays or swap setups with limited clearance.
• Lower Amp Draw: Typically uses less power than a dual fan system.
• Budget-Friendly: Usually less expensive than dual setups.

Disadvantages:

• Cooling Limitations: Might not move enough air for high-performance engines or cover large radiators without using a shroud.
• Limited Redundancy: If the fan fails, there’s no backup fan to aid the cooling system, which can lead to overheating.

Dual Fan Setup

Advantages:

• Better Cooling Performance: Two fans can move more air, ideal for high-HP builds, A/C-equipped vehicles, or heavy-duty use.
• Staged Operation: Fans can run independently based on temperature or load (primary for normal, secondary kicks in during heavy load or for when A/C is commanded, etc.).
• Redundancy: If one fan fails, the other can still provide some airflow to the cooling system and get you home.

Disadvantages:

• Tighter Fitment: Takes up more space—can be tricky in compact engine bays.
• Higher Electrical Demand: Requires a strong charging system and a relay/fuse setup for each fan, or a dedicated dual fan controller.
• More Complex Install: More wiring, more relays, more things to configure or troubleshoot depending upon how you want the fans to work (independently or combined).

Straight Blade Fans

• Performance: Provides higher airflow capability. Straight blades move a lot of air quickly, which is great for aggressive cooling needs.
• Strong Pulling Power: Often favored for race or off-road use where max airflow is a priority.
• Noise Level: Known for producing more noise due to the abrupt movement of air, the straight blade fan can sound like a vacuum or even a small jet engine at full speed.
• Best Suited For: Race cars, off-road trucks, drag builds—anywhere cooling is more critical than noise comfort.

Curved (S-Curve or Swept) Blade Fans

• Performance: Slightly lower peak airflow vs. straight blades, but more efficient in low-to-mid rpm use with smoother airflow.
• Reduced Turbulence: Blades slice through the air more gradually, which leads to quieter operation.
• Noise Level: Curved blade cooling fans are much quieter. Often the go-to for street cars, daily drivers, or anything with a sound system or A/C where cabin noise matters.
• Best Suited For: Street cars, restomods, cruisers, and anything where comfort and reliability matter more than the highest CFM radiator fan.

When it comes to straight blade vs curved blade radiator fan discussions there are often a few misconceptions that pop up. For one, is the age old “more blades equal more cooling.” While additional blades can increase CFM, blade shape, motor rpm and other factors are more important in determining overall fan cooling ability. Another is “straight blade fans outperform curved blade fans.” In maximum CFM, yes, but in real world use, curved blade fans, especially when used with thermostatic fan controllers, often maintain consistent and better temperature averages with less draw on the electrical system. Lastly, is the “curved blades are weak” argument. Since the modern curved blade is CAD designed using modern synthetic materials and engineered for maximum efficiency and noise reduction and not maximum airflow like a straight blade fan, the curved blade fan provides the proper strength for the fan diameter and motor speed without being weakened.

Common Causes of Fan Noise:

• Motor Type: Brushed motors tend to make more noise due to internal friction. Brushless motors run quieter and smoother.
• Blade Design: Straight-blade fans move a lot of air, but they’re louder doing it. Curved blades are quieter but may flow slightly less total CFM.
• Fan Speed: High CFM fans pull serious air—and that airflow makes sound, especially at full power.
• Mounting Issues: If the fan isn’t securely mounted or is contacting nearby parts (like shrouds or radiators), it can vibrate or rattle.

Tips to Reduce or Prevent Noise:

• Use Rubber Isolators or Grommets: An isolating gasket or grommets around mounting fasteners help reduce vibration between the fan and radiator or mounting surface.
• Check for Clearance: Make sure the blades aren’t hitting anything, especially in tight engine bays.
• Upgrade to a Brushless Fan: It’ll run quieter, last longer, and use power more efficiently.
• Go Curved Blade if Possible: For street cars or cruisers, curved blade fans offer a nice balance of airflow and quiet operation.
• Use Variable Speed Controls: Fans running full speed all the time are louder. A fan controller can help manage speed based on engine temperature. A pulse width modulated fan controller with brushless S-blade fan is your best option if it has sufficient cooling capacity for your needs.

Based off the chart above we’ve provided some further examples of the use cases listed in the chart along with amperage needs and some tech tips as well.

Examples of Engine Types:

• 4-Cylinder: Miata, Civic, daily drivers, compact cars, light duty
• V6 / Small V8 Engines: Stock V6 / S10 chassis swap, midsize cars, small pickups, street builds
• Early Small Block V8 / Modern V8: Stock V8 swaps, stock 5.3L LS in a C10, classics, muscle cars, mild LS swaps, tow rigs
• Big Block V8 / Modern Performance V8: 496ci in a Chevelle, modified LS or Coyote, full-size trucks, modified street
• Race / Boosted V8s: Turbo/supercharged LS or HEMI over 500+ HP, forced induction, drag cars, track builds

Amperage Notes

• As airflow increases, so does the current draw. Most single fans pulling 3,000 plus CFM can draw 20–30 amps or more (and spike to 50-70 amps on start up!)
• Dual setups pulling 4,000–5,000 CFM may demand 40–60 amps total—upgraded wiring, relays, and alternators are required.
• Use a fan controller or thermostatic switch to manage when and how the fans kick on (especially useful for dual setups).

CFM Range to Typical Amp Draw Guide (Approximate)

• 1,200 to 1,600 CFM will draw 8 to 12 amps
• 1,800 to 2,200 CFM will draw 12 to 18 Amps
• 2,400 to 3,000 CFM will draw 18 to 25 Amps
• 3,000 to 4,000 CFM will draw 25 to 35 Amps
• 4,000-plus CFM will draw 35-plus Amps

Electric Cooling Fan Installation Tech Tips

• Always measure your available space before choosing a fan. Higher CFM units are typically thicker.
• A shroud can improve cooling efficiency by directing all airflow through the radiator core, especially on puller style fan(s).
• If your system struggles to keep up, check if the fan direction is correct (push vs pull), voltage at the fan motor, and for proper ground.

As a rule of thumb, you’ll find most high performance single fan applications run 15-20 amps, though you might see larger fans, or high-CFM fans upwards of 30 amps continuous use. Dual fan setups can usually just double these numbers (30-40 amps), but again, you will see some higher amp needs with larger fans. Of course, you will see a lower amp draw with brushless motors for the same CFM and diameter (another great reason to go with a brushless electric radiator fan!). Dual fan setups will see peak amperage at start up when both fans are wired/controlled to engage together. Having a dual fan setup wired/controlled in stages so that the fans come on separately as needed will lessen the stress on the electrical system.

Once you have your fan chosen you will need some way to power it. As a minimum a relay will be required to operate an electric fan since the amperage draw can easily exceed the capacity of most ignition switches. So, when asking “Do I need a relay for electric fan use?” the answer is most definitely yes for all but the smallest cooling fans usually reserved for oil coolers. Be sure to select a relay with the proper amperage rating to meet the needs of your fan. A 40 amp relay is common for use with many electric fans but some high flow fans will require a 70 amp relay. Obviously, you will need to use the appropriate gauge wire as well when adding in the relay(s). We recommend at least 12 gauge wire, but higher amp fans/controllers may require 10 gauge or even 8 gauge in some instances. When in doubt, follow standard wire ampacity charts. It is better to be oversized a bit on your fan wiring (and use quality connections to reduce resistance!) than to be undersized and have your fan wiring overheating/melting. Lastly, don’t forget to fuse your inputs. You’ll want to use a fuse rated slightly higher than the fan’s amp draw (30 amp fuse for a 25 amp draw, etc.). If you find your electric radiator fan not working the first item to check should be your ground circuit (both the relay and the fan ground itself). Poor grounds are the number one issue with electric cooling fan installations.

The simplest method of wiring electric fans radiator option is to use a relay that is switched on and off by the ignition switch. This method works well to cool the vehicle, but the drawback is the fan will be running constantly when the ignition is on. Fan noise and added electrical system load will be present at all times. Are radiator fans supposed to run all the time? Quality made fans have a long service life, and brushless fans have no internal parts to wear (other than motor bearings), so running the fan(s) any time the ignition key is on isn’t usually a problem these days.

A better option for how to wire up electric radiator fan and keep it simple is to add a thermostatic switch which reads the coolant temperature and switches the fan on and off as necessary. This is an extremely popular option due to the low cost and simplicity of the system. Many electric fan temperature switch kits are available which includes the temp sensor, relay, and fuse holder. The coolant temperature at which the fan will be turned on or off depends upon the sensor used. There is no adjustment using this system, but the sensor can be changed to a different temperature rating if desired.

The next step up is an adjustable fan controller. Several options are available such as our adjustable fan thermostat controller which allows for adjustment of the coolant temperature at which the fan will run. This is an excellent choice for many applications since all that is necessary to adjust the temperature setting is to turn a knob. No need to break the cooling system open to change out a temperature sensor. With temperature adjustment being so easy this works well for vehicles that see some track time. You can adjust your temperature lower for the track to maximize power, then raise it back up while cruising the streets for maximum efficiency.

Pulse width modulated fan controllers (PWM) are the latest technology to come to electric fan control. This will control the amount of power that is supplied to your fan and allow it to run at variable speeds. All other controllers simply turn the fan on or off and when the fan is on it will be running at full speed, not to mention the major amp draw on initial start-up. With a PWM fan controller it will send only the amount of power necessary to maintain the set temperature. This further reduces electrical system load and keeps fan noise to a minimum. Another notable feature of PWM controllers is the soft start feature. This will start the fan slowly and then ramp up the power as necessary so that an instant surge of power draw is eliminated.

A special note for A/C applications: A trinary switch is a must have item when installing an electric fan on a vehicle that has air conditioning. But what is a trinary switch? This switch senses pressure in the air conditioning system and will turn the electric fan on any time the A/C is being used. This aids in air conditioning system performance by pulling more air across the condenser which is mounted in front of the radiator. It is especially helpful at low vehicle speeds, stop and go driving, and when parked or idling.

How often should my radiator fan come on? Your electric cooling fan should engage whenever your cooling system reaches the temperature you’ve set in your fan controller or the temperature of your pre-set fan temperature switch (for example, 180 degrees). For most applications, once this temperature has been reached the fan will stay on. In cooler weather your fan may not come on at all or it may cycle as the engine heats up and is cooled by the radiator.

Concerns with running 4 core radiator with electric fan? When it comes to thicker radiator cores some low-profile fans, and smaller diameter fans as well, can have issues pulling enough air through these cores, as the static pressure (resistance) is higher in these applications. Running a larger diameter fan and/or one with more power will overcome this static pressure issue and cool your engine, even at low speeds or under heavy use.

Do I need a fan shroud with an electric fan? In most cases, the answer to do i need a fan shroud with an electric fan is yes. Using a fan shroud is preferrable when mounting an electric cooling fan, as the shroud helps direct all air pulled in by the fan passes through the entire core and not just the surface under the fan’s housing/blade diameter. This improves cooling efficiency. However, in some instances there may be insufficient room to run a shroud, or the fan must be offset for clearance needs. In these cases, it may be best to run multiple fans to ensure adequate radiator core coverage.

How far should electric fan be from radiator? You’ll want the fan’s blades to be positioned between one and two inches from the radiator core for maximum airflow through the core. Too close and you’ll induce turbulence; too far away and you’ll reduce the fan’s effectiveness. Be sure to consider the fan housing depth when checking fan spacing, as direct mount fans will often have an inch or more of spacing built into their design.

Who makes good radiator fans? There are several manufacturers of automotive electric radiator fans and you’ll find them available right here at Speedway Motors in multiple diameters, CFM ratings, and pusher or puller electric fan configurations.