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  1. Radiator Fans
  2. Derale
  3. 4000 CFM
  4. 27 Inch Diameter
  5. Electric Fans
  6. High-Output Fan
Derale 27" Dual, High-Output Electric Radiator Fan w/ Aluminum Shroud - PWM - 4,000 CFM

Derale 27" Dual, High-Output Electric Radiator Fan w/ Aluminum Shroud - PWM - 4,000 CFM

Item # D66837
Our Price: $589.19
You Save: $57.03
Radiator Fans
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Shipping Weight: 19 lbs
Derale 27" Dual, High-Output Electric Radiator Fan w/ Aluminum Shroud - PWM - 4,000 CFM 27 Inch Diameter D66837
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27" Wide x 18" tall x 4" deep. 4,000 CFM high-output dual electric puller fan cools efficiently and quietly. Variable-speed PWM controller. Dual 300-watt, 24.8-amp motors. Vented aluminum shroud offers top or side mount. Great Prices for the best radiator fans from Derale. Derale 27" Dual, High-Output Electric Radiator Fan w/ Aluminum Shroud - PWM - 4,000 CFM part number D66837 can be ordered online at or call 1-833-496-1390 for expert service.
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Derale Radiator Fans - D66837

  • 4000 CFM
  • 27 Inch Diameter
  • Electric Fans
  • High-Output Fan
  • Derale

27" Wide x 18" tall x 4" deep. 4,000 CFM high-output dual electric puller fan cools efficiently and quietly. Variable-speed PWM controller. Dual 300-watt, 24.8-amp motors. Vented aluminum shroud offers top or side mount.


  • High-output, dual radiator puller fan helps maintain optimal engine operating temperature
  • Efficiently moves 4,000 cubic feet per minute (CFM) of air at 0 static pressure
  • Restores horsepower and torque used by belt-driven fans
  • Draws power from the alternator, not the engine, with minimal mechanical load
  • Integrated pulse-width modulation (PWM) controller allows precise, variable fan speed control
    • Continuously monitors your engine's temperature
    • Runs fan only at precise speed needed for cooling, between 0-percent and 100-percent power
    • Can operate additional fans - up to 65 amps maximum capacity
  • Powered by dual 12V, 300-watt motors that draw 24.8 amps each
  • Soft-start technology powers up engines gradually to prevent amperage spikes
  • Moves air efficiently and quietly with skewed blades
  • Resists moisture and dirt with waterproof (IP-68) and dustproof motors
  • Increases airflow velocity with vented shroud
    • Rustproof aluminum shroud acts as a wind tunnel
    • Built-in vents relieve excess air pressure
    • Shroud can be painted, polished, or anodized
  • Designed for top or side mounting
  • Includes brackets, hardware, and installation instructions
  • Made in the USA


  • Overall dimensions: 27" wide x 18" tall x 4" deep
  • Fan diameter: 12"
  • Mounting dimensions:
    • Width: 18-3/4" - 24-3/4"
    • Length: 10-1/2" - 16-1/2"
  • Maximum CFM per fan: 2,000
  • Power draw per fan: 24.8 amps
  • 1-Year warranty

Derale A12 Dual Powerpack

Note: This assembly is intended for primary cooling and should provide enough airflow to replace your vehicle's factory fan, but you will still need to determine the CFM requirements for your engine before making your purchase. Engines that have been modified or vehicles used for towing may require additional CFM. There is no limit to the number of fans you can install, as long as they fit appropriately and are mounted on the same side of your radiator so that they do not cancel each other out.

You can install the Derale Dual Powerpack as a horsepower-boosting replacement for your belt-driven radiator cooling fan, or you can use it to upgrade or expand to your current electric fan system. The dual fan cools your engine by pulling 4,000 cubic feet per minute (CFM) through your radiator at 0 static pressure. High-output, 300-watt motors and skewed fan blades do the job efficiently and quietly. It keeps engine loads to a minimum by drawing power (49.6 amps) from the alternator - not the engine itself. An integrated pulse-width modulation (PWM) controller offers maximum cooling control and greatly reduces wear and tear. Fans operate only when needed - at the speed needed - for engine cooling. The Powerpack is neatly packaged in a slim, customizable aluminum shroud that offers multiple mounting locations and won't hog lots of space in your engine compartment.

Power Increase Compared with Belt-Driven Fans

Belt-driven radiator fans draw power from your vehicle's engine, which causes a mechanical load that robs the engine of valuable horsepower and torque. The Powerpack, on the other hand, gets its power from your vehicle's alternator, via your vehicle's 12-volt electrical system. The Powerpack's 49.6-amp draw is far less taxing to your engine than a belt-driven fan's mechanical load. So replacing your belt-driven fan with an electric fan system can increase available horsepower and torque - and even improve fuel economy.

Pulse-Width Modulation (PWM) Controller with Soft-Start Technology

Derale Dual Powerpack with Integrated PWM controller

The Powerpack's controller uses pulse-width modulation (PWM), which enables it to achieve and maintain the perfect operating speed for optimal engine cooling. The controller does this by adjusting the fan speed based on continuous, real-time engine temperature readings collected from the included sensor, which is mounted on the cool side of the radiator. Unlike conventional fan switches that have only 2 settings - on and off - the PWM controller operates at variable power levels from 0 percent to 100 percent. In some cases, for example, the engine can be kept at the desired operating temperature with fans running at between 40- and 60-percent of full operating speed. Lower operating speed means fewer cycles for the motors, which saves wear and tear and thereby potentially prolongs the life of the motors.

Soft-start technology helps protect your vehicle's electrical system by ramping fan motors up to operating speed slowly to eliminate harmful amperage spikes.

Increased Cooling Efficiency

The Dual Powerpack pulls mass quantities of air through your radiator's fins using twin fans, each powered by a 300-watt motor. The patented, skewed fan blades are designed to move air with as little noise as possible. Each fan grill is actually a stator flow director that helps produce maximum velocity by aiming the outflow.

Rustproof Aluminum Shroud

The Powerpack's rustproof aluminum shroud can be painted, polished, anodized, or left with its natural finish for a custom look. The shroud also serves as a wind tunnel so that air exits the fan quickly. Built-in air pressure relief vents help keep the static pressure load in check.

66837 Derale A12 Dual Power Pack High-Output Variable Speed RAD Fans with Pulse Width Modulation Controller - Aluminum Shroud


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Info for this part was:

Employee Brian B
Written by:
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Employee Daron K
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