Originally Posted by Wade Mahaffey

Phill, The single biggest issue that I've seen in race cars, is no fan shroud. Most set-ups out there are either a water pump mounted fan with a Moroso drive motor, or an electric fan in a black plastic housing held on with plastic ties. Neither of which draws air thru the complete core. It's like you pulling two plug wires off before you go in the water box! Check your combination with this formula: measure the radiator core L x H = Sq. In. (example 20" x 18" = 360 Sq. In.). Now for the round fan, the formula is Diameter square x .7854 (exanple for a 16 inch fan: 16 x 16 x .7854 = 201 sq. In.). Now subtract the fan from the core (360 - 201 = 159). That means 159 square inches or 44% of your radiator has no fan drawing air thru the core. And you know what happens if you leave the fan off...it ain't pretty! but you're always leaving the fan off of 44% in this example!

The key is to move water as fast as you can, but you must be able to extract BTUs or heat from it while it passes thru the radiator. In order to do this, you must draw air thru ALL OF THE CORE and not just 44%.

Some folks say put washers in place of the thermostat to slow the water and hold it in the rad longer (to allow more cooling). But if you do that, where else are you holding the water?....the engine...and if it's there longer...it's getting hotter! Cool it better and run it thru faster! Ever wonder why the water pump companies make a pump rated @ 55 GPMs, it's not so you can put a washer with a 5/8s hole in the t-stat housing. Get the hot water out quicker....and the cool water in quicker! LOL

The use of a well made Shroud (sealing 100% of the rad core) and an electric fan combination will extract the maximum BTUs and provide your radiator to see it's full potential.

You would be suprised what that could do for your round-robin package!

Here's what I use



Wade Mahaffey