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Keep Your Cool – Increase Your Horsepower – SPAL USA Makes Controlling Your Engine Temperature Easy!

Written by  Ansen Thigpen

This is the Javelin’s engine bay complete with the factory stock crank driven cooling fan.

Your engine compartment is a hot and hostile environment where hot gasses, scalding engine coolant and oil circulate in the block and cylinder head of your engine. This heat wreaks havoc on all components of your engine, and left unchecked this heat will ultimately destroy your engine. Naturally automakers have addressed this problem by incorporating a radiator in the front the engine that uses cool ambient air that passes over the fins and tubes and helps to remove the heat from the coolant before it returns to the engine.

The stock cooling system does a very good job of maintaining the proper coolant temperature to prevent engine killing detonation and other problems like a head gasket failure. The problem with the stock cooling system is that when significant engine upgrades are performed and higher power levels are reached, the limits of the stock cooling system are pushed and often exceeded. There are several different ways to address this issue, but the best approach is to increase the air flow through the radiator, increase the cooling capacity by use of a larger or more efficient radiator, or by tightly controlling when the engine needs to be cooled. All of these methods will improve the cooling efficiency and improve the power output of your engine.

All modern vehicles with the exception of full size trucks and SUVs employ electric fans to help draw cool ambient air through the radiator core. Each fan has a predetermined flow rating of how much air it can move given the voltage that is being supplied to it. The only way to increase the amount of air that is being drawn or pulled through the radiator is to either increase the RPM of the fans or employ a more efficiently designed fan. As you may have guessed, not all fans are created equal and the size of a fan doesn’t necessarily relate to the performance capabilities of said fan. For example, a large fan may be less efficient than a smaller fan with a superior fan blade design.

So the solution is simple: just install a pair of high efficiency fans and you’ll be good to go right? Well yes and no. The problem with upgrading your cooling system with high efficiency fans is that you can actually cool the engine too much, which can result in higher emissions and compromised engine performance. This is especially true if one uses a toggle switch to activate the fans. Ideally one would want the cooling fans to operate only when the engine is approaching the limit of normal operating temperature. This would be especially useful when operating the vehicle in mixed driving situations such as stop-and-go traffic as well as drag racing where the engine is warmed up, raced and then shut down for as long as an hour or more. Traditionally the problem was that you would have to rely on a thermo switch mounted in the radiator or intake manifold that would trigger a relay to activate the fans at a predetermined temperature, which wasn’t always effective.

Thankfully the engineers at SPAL have developed a product that takes the guesswork and risk out of properly controlling electric cooling fans. The SPAL PWM V3 programmable fan controller allows the user to variably adjust the speed of the cooling fan(s) based on the engine temperature. The SPAL PWM V3 is easy to use and only requires the user to program a high and low temperature setting. When the engine reaches the low temperature setting, the SPAL PWM V3 operates the primary fan at 50% of their maximum speed.  As the engine speed increases the unit adjusts the speed of the fan proportionately to provide proper cooling when the engine needs it until the engine reaches its maximum operating temperature where the fan will operate at 100%. This function is not only clever but it increases the lifespan of your fans significantly by not allowing them to operate at 100% all of the time.

The SPAL PWM V3 is also capable of operating a second fan with the use of a relay harness (available from SPAL USA). The second fan will be activated once the primary fan has reached full speed.  Another feature that many will find useful is the ability to operate the fans at 100% when the air conditioning system is engaged. The SPAL PWM V3 is compact and rugged – perfect for the hostile under hood environment of any engine.

In this article we installed the SPAL PWM V3 and 2VA06-AP70/LL37A Dual 11-inch Fans into a 1974 AMC Javelin that is in the process of being restored. This vehicle was saved from rotting away in a farmer’s barn. The Javelin has always been in the new owner’s family, and after a frame up restoration the car is beginning to see the light at the end of the tunnel. The owner has owned several high performance vehicles – mainly imports – and knew the value of doing things right the first time, which is why SPAL USA products were selected for this project. The car is primarily a street machine that will see some drag strip duty so the engine would definitely be exposed to the stop and go of the city and abuse of the Saturday night drags. The engine is going to have an air conditioning system retrofitted to it so the stock cooling system will definitely be pushed to the limits if not beyond. The SPAL USA Dual 11-inch Fans are capable of moving 2780 CFM of air. Radiator measurements were taken and it turned out it matched perfectly with the SPAL USA fans.

The install was very straight forward and took approximately 2 hours to complete. Easy to read instructions were supplied with the products and technical support was readily available when required. The owner was very pleased with the finished product and the performance of the new and improved cooling system. This process can be adapted to virtually any vehicle regardless of make or model including marine applications because the SPAL Dual 11-inch Fans are waterproof.



1731 SE Oralabor Rd.

Ankeny, IA 50021-9412

(800) 345-0327


The owner replaced the stock radiator that was in poor shape with a Blackstone radiator.

Because the Javelin has been restored, the owner places cloth diapers on the fenders to protect the new “Viper Blue“ paint from accidental damage.

The upper radiator hose clamp is removed from the radiator hose.

Once the clamp is loose the hose can be disconnected from the radiator.

Next the cooling deflection plate is removed from the top of the radiator support. This simple piece defers air towards the radiator instead of riding the inside of the hood and out the cowl.

The coolant temperature sensor is threaded into a port on the intake manifold; this is where an accurate temperature reading for the control unit will be taken.

Now the bolts that secure the radiator to the chassis can be removed.

Once the nuts are loosened the bolts can be removed by hand easily.

Next the clamp on the lower radiator hose is loosened and the hose removed from the outlet.

The Blackstone radiator can now be removed from the engine compartment.

Now that the radiator is completely out of the car, we’re ready for the SPAL USA Dual 11-inch Fans.

The SPAL USA Dual 11-inch Fans are test fitted and all looks splendid.

The fan is mounted and secured.

The stock cooling fan was removed from the water pump prior to the article when the engine was installed. The deletion of this fan will reduce parasitic drag on the engine, which will result in increased power and response.

With the fans securely mounted to the radiator, the entire assembly can be reinstalled into the engine.

The upper coolant hose is reinstalled.

Now the hose clamp can be tightened as the radiator will not be removed again.

The next step is to install the SPAL USA PWM V3.

For ease of installation, the unit and associated harnesses and hardware are laid out.

SPAL’s temperature sensor harness, which comes pre-loomed, is unwrapped.

The harness is connected to the sensor and hidden from view.

The other end of the harness is connected to the SPAL USA PWM V3.

With one harness plugged in, it’s time for the next one.

These two wires aren’t going to be used at the moment but when the air conditioning unit is installed they will be used to trigger the unit when activated.

We’ve simply coiled them up and used a tie strap to secure the wires to the chassis.

A suitable ground is found on the firewall.

Next the wire harness for the fan relay is tucked away out of sight.

The other end of the harness is connected to the fan motor.

The ground from the unit is terminated and connected to the negative terminal of the battery.

The power wire is stripped and connected to the fuse holder that was supplied with the kit.

A location above the battery is selected for secondary fan relay.

Here we see the secondary fan relay and fuse for the SPAL USA PWM V3 unit.

The harness for the secondary fan relay is connected to the second fan at the bottom of the fan shroud.

Next the ground for the cooling fans is bolted to the radiator support.

All of the wiring is neatly hidden within a loom that was purchased from a local auto parts supply store for a tidy appearance. Now the Javelin is ready to run nice and cool on the open road or at a dead stop idly strong and mellow in a traffic jam.

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