Volume III, Issue 3, Page 39

See the added weather strip seal between the fan and the radiator (mentioned previously)? This high-temperature seal increases the fan’s efficiency by a considerable margin and is like adding a shroud to an engine-driven fan.

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 missing, this situation creates a considerable amount of dead space behind the radiator that in turn destroys the effectiveness of the fan assembly.

Push or Pull?

In the case of electric fans, there are two options:  A pusher or a puller. Detroit has used both configurations, 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 radiator). 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 also be a good choice for a car that's either blessed with a cooling dilemma or one that sees double-duty as a weekend racer.

The hose on this Chevy pickup is the formed type, not the one-fits-all ribbed stuff that is readily available and dirt-cheap.  The formed hose does not promote laminar flow losses inside it. The ribbed junk does. If you have an unusual application and can’t find any form-fitting hose, bend a length of appropriately sized tubing to fit and make the connection with a short piece of form-fitting rubber hose. Note too, the bead formed at the respective ends of the tubing to retain the rubber hose (and clamps). Copy it.

What's Best?

Which fan is best for your car depends on the application and the room available.  If you have the space, 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. The worst possible arrangement is an inexpensive discount store flex fan without a shroud or a single pusher electric without a shroud. All of the other combinations fall somewhere in between.  


Ron Davis Racing Products
623 877-5001

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