Leading A Horse To Water…
All of the above electric fans have a low amp draw, but Ron points out that one of the other secrets to properly cooling a drag car is to effectively seal the radiator to the fan. Typically, this is accomplished with an integral shroud surrounding the entire electric fan(s). The shroud simply allows the largest volume of air to be pulled through the rad (typically in a pull-through application).
There’s more too: When it comes to cooling you absolutely must figure out a way to bring the air to the cooler. The idea is, of course, to provide a constant supply of air through the radiator so the coolant is reduced in temperature. Increasing the airflow through the radiator improves the cooling and as a result, a
shroud is almost mandatory on high performance applications, and that includes your bracket racer. Unfortunately, they are often missing on many older cars or were never installed on a freshly built car. Keep in mind that over the years, OEM shrouds were often manufactured from plastic and as result, the condition typically degrades dramatically over the years. If you don’t have a shroud or if it fits poorly, get one (it's a big hint if you end up sitting behind Old Faithful on a regular basis).
How does the shroud work? Basically, the shroud surrounds or partially surrounds the fan. It butts up tightly to the face of the radiator, effectively sealing the cavity. This isolates the pocket of air behind the radiator, allowing the fan to efficiently draw the required air through the radiator. If the shroud is not present, it creates a considerable amount of "dead" space behind the radiator that in turn destroys the effectiveness of the fan assembly. The bottom line is simple: If you don't run a proper shroud, you're only asking for overheating grief.
See the hose used on this Chevy pickup? (I know, it’s just a tow/shop truck, but it’s still important.) The hose is formed, not the fits-all ribbed stuff that is readily available and dirt-cheap. The formed hose does not cause grief with laminar flow losses inside the hose. The ribbed junk promotes it. Use a formed hose. You’ll be much happier.
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| If you have an unusual application and can’t find any form fitting hose, try this: It’s simply tubing bent to fit the application. Then a short piece of rubber hose is used to make the connection. Note too, the bead formed at the respective ends of the tubing to retain the rubber hose (and clamps). Copy it. It’s good engineering. | |
Push or Pull?
In the case of electric fans, you usually have two options: A pusher fan or a puller fan. Detroit has used both configurations in modern passenger cars and light trucks, although puller fans are the most common. Sometimes electric fans are used in conjunction with an engine driven clutch fan (typically, an electric pusher fan mounted ahead of the rad). This arrangement is particularly useful if heavy cooling tasks are mandated by the application (a good example is a pickup truck with a factory towing package). This might be a good choice for a bracket racer that's either blessed with a cooling dilemma or one that sees double duty as a weekend racer.
What's Best?
So which fan is best for your bracket racer? It all depends upon the application and the room you have to work with. If you have the room, a pair of high quality, low amp electric puller fans, complete with an integral shroud (as shown in the accompanying photos) is pretty much the ultimate for bracket racing. The worst possible arrangement is an inexpensive discount store flex fan without a shroud or a single pusher electric without a shroud (with these setups, you're only asking for trouble). All of the other combinations fall somewhere in between.
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When all is said and done, there is virtually no way to "over cool" your bracket racecar. And the more power your engine produces, the more cooling capacity you'll need. When shopping for hardware, buy good quality parts and make sure the fan, hoses and shroud are appropriate for the application. If you don’t pay attention to this stuff, you’ll eventually come to regret it.
Click here to read Part 1.
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