[P@blo]

Originally Posted by Schurkey

The clutch fans have a known RPM limit, about 4800 rpm if I remember right--it's on the Hayden web site if anyone wants to look it up.

Since the water pump is typically spinning faster than the crank...the fan clutch is turning faster than the tach suggests, by whatever the pulley ratio happens to be.

The saving grace here is that the fan clutch is also slipping some, the fan clutch is turning faster than the crank, but the fan isn't due to fan clutch slippage.

Yet another reason to NOT use the "Heavy Duty" or "Severe Duty" fan clutches (that don't slip properly when used with typical automotive fans) in a performance application.

Its interesting how the Hayden website says to use both the heavy duty and the severe duty clutch the fans over 2.25" pitch.