DIY Garage on Summit, How To's by David Fuller A couple weeks back, we asked the question: Mechanical vs. Electric Fans: Which is Best for Your Vehicle? If you’ve determined that an electric fan is the best choice for your ride, you’re certainly not alone. Electric fans have become the preferred choice for many enthusiasts because they have lots of advantages over mechanical fans, including: Good cooling with no parasitic horsepower loss Consistent cooling—they maintain their airflow at all times 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 The next logical question is: “Which electric fan is right for my vehicle?” With help from our friends at Flex-a-lite and input from the Summit Racing tech department, we’ve identified four keys to choosing the right electric fan for your application. 1. Establish the Need If you haven’t read our original post on mechanical and electric fans, start there. You’ll learn that, in some cases, the stock clutch fan or an aftermarket flex fan will work just fine. Remember, though, a mechanical fan is driven by your engine. If your engine is spinning at low rpm, so is your mechanical fan—and that means there will be less airflow at lower engine speeds. If you notice your vehicle running a little hot in traffic or at low rpm, an auxiliary electric fan may be just what you need to give your primary fan a cooling boost. 2. Determine Optimum Airflow Companies like Flex-a-lite rate their electric fans by horsepower and airflow levels—simply choose the one that is rated the same as or higher than your vehicle’s power output or airflow requirements. Flex-a-lite recommends these minimum cubic feet per minute (cfm) ratings when using an electric fan as the primary cooling source on a basic engine: 1,250 cfm for a 4-cylinder 2,000 cfm for a 6-cylinder 2,500 cfm for a 8-cylinder Engines that are 5.0-liter (302 cubic inches) or larger should use an electric fan with 2,800 or more cfm. Obviously, an 800-horsepower engine will need more cooling than a 300-horsepower powerplant regardless of the cylinder count. Again, many electric fans are rated by recommended horsepower to help you get the optimum amount of airflow. 3. Measure It Up Once you know the minimum cfm required, you need to determine what will physically fit. This is easiest to do if you remove the belt-driven fan and fan shroud so that you can accurately measure the radiator and the distance between the radiator and engine components. You should also measure the radiator core, which is the finned surface between the two tanks. You’ll want to select a fan that covers as much of this space as possible. In many cases, you will be better off with a dual fan because the shroud will pull air through a larger area of radiator than a single fan. Next, measure the distance between the radiator core and the closest engine component. You can supply these dimensions to your sales rep or consult this handy Flex-a-lite chart, which helps match the right electric fan to your dimensions. 4. Choose Pusher or Puller Electric fans are available in pusher or puller designs. Pusher-style fans mount on the front of the radiator and blow air through the radiator core. Puller-style fans mount behind the radiator and draw air through the core. Puller-style fans are recommended for applications in which the electric fan is the primary cooling source. A pusher-style fan can be used as an auxiliary cooling source, but you should sure make the fan covers as much of the radiator core as possible. This goes back to measuring and determining the right dimensions for your fan. Don’t spend valuable cruise or car show time sitting on the side of the road. Take the first four steps toward avoiding an epic summer meltdown—and keep your ride firing OnAllCylinders!