On the subject of clutch fan drives (previous page) never mix blades with the wrong clutch fan drives.  If in doubt, measure the pitch of the blade first.  To measure the pitch, lay the fan blade face down on the bench.  Measure from the highest point of the bend halfway down the blade.  If it's under 2.5 inches, it will require a standard clutch drive.  If it's over 2.5 inches, you will use a heavy duty or severe duty clutch fan drive.  Never mix them!  Never use a standard clutch fan drive with heavy duty or severe duty fan blades or visa versa.  It will not perform correctly and will run hot!

This fan dyno was built to be able to test and find the correct fan for various applications.  This is a very tricky deal and depends on a lot of different circumstances, like engine size, horsepower and pumping compression.  It's easier to cool a smaller engine with less horsepower, than a bigger engine with more horsepower and more compression, which creates more heat.  We found the 88' to 90' Taurus 3.8 V-6 two speed fan covers a wide variety of applications.  It can be used on low speed only, most of the time.  Personally, I would think twice before replacing the clutch fan drive system with something else.  Just build a complete fan shroud.  They work great!!

The next step, is to have a well designed fan shroud.  The system needs to decompress the air before  it enters the radiator core.  If not, it will not cool properly.  Actually, this is a good way for you to test the efficiency of your system.  To set-up the dyno, we used Ford Taurus 3.8 V-6 fan to create our baseline.  The pictures below is an Electric Fan Dyno for testing electric fans.

                                        We also do matching numbered pumps!