By now, most of us know that a variable fan will speed up as a car’s engine heats up. What you might not realize is a well-engineered fan setup with properly functioning sensors will never go faster than needed in order to maintain a pre-set temperature. However, not everyone knows that the whole CFM (cubic feet per minute) fan performance rating is by no means useful or applicable to most automobiles?
We recently caught up with SPAL Automotive USA, and the company’s Application Engineer, Brent Chuck, to get the skinny on the latest brushless fans, and to see if all those CFM claims are little more than a bunch of “hot air.”
Before we get too deep into all things CFM, here’s a fun little fact. Did you know that SPAL’s 14-inch fan is what is found in the C7 Corvette? Complete with chassis-specific shrouding, you can easily see how OEM contract projects such as these have breathed life into many of SPAL’s aftermarket fan applications over the years.
The reason for this is simple. Traditionally, OEM’s viewed bigger and more powerful fans as the best way to move air, whereas SPAL prefers the smaller and more efficient approach, with 16-inch 500W fans being the brand’s “big boy on the block.” The brand not only has found ways to engineer more efficient motors and curved blades, but it also enlists the help of sensors with pre-programmed temperature ranges. This helps eliminate things like relays, as you source power straight from the battery.
From a DIY viewpoint, this makes for an extremely simple plug-and-play fan, sensor, and harness cooling solution, especially when SPAL’s new brushless fans are put into play. Ordering is further streamlined by this methodology, as all one has to do is pick the temperature range they need, the size fan and shroud they require, and then click order. It’s really that simple.
As for the whole brushless fan debate, rest assured in knowing that these types of fans truly are better in every measurable way, save for when it comes to price. (We’ll revisit that part when we cross the finish line.)
At full speed 100-percent of the time, 24 hours a day, SPAL’s brushless fans are expected to outlive a standard fan setup 4–5 fold, which breaks down to brushless fans offering at least 40,000 hours of longevity. In comparison, a normal, non-brushless fan, only has about 5,000–15,000 hours of life on average.
Now as for the whole CFM nomenclature, and the hype surrounding this rating, Chuck tells us that it all boils down to numbers, and more importantly, the obsession gearheads have with really large numbers. Yes, CFM is a legitimate form of rating a fan’s strength and efficiency, but bigger does not always constitute better. You can have a 1,000 horsepower drag car, but anywhere below 800 rpm those numbers mean nothing, and the same goes for CFM ratings and their zero pressure testing standards.
Never use CFM to rate a fan… the reason being is that a CFM rating is done at zero pressure, [which] is basically the worst point on the airflow curve to compare two fans… -Brent Chuck, SPAL
With the CFM record officially set straight, we turn to the aftermarket community, which Chuck is eager to both commend and chide. Despite having developed a safe and easy plug-and-play brushless cooling fan application, SPAL’s engineer admits that a lot of people don’t even use SPAL’s sensors. Instead, they prefer to wire their cooling fan set up straight to the ECU for mapping and tuning purposes.
Here, he forewarns that increased controllability opens the door to a large margin of error, so be mindful of your ECU tune if you opt for this approach. This is because a properly functioning fan is vital to the performance (and lifespan) of your engine.
Regarding price, Chuck informs us that while there are some variances in the final cost, single brushless SPAL fans tend to run in the $450–$500 range, with a full shroud, sensor, harness setup setting you back a “cool” $700 or so. Dual brushless fan setups on the other gear, typically start at $700, and run all the up to around $1,000, but include everything you need accessory and install wise, straight out the gate, and onward to the finish line.