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dspeed

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PwrWgnDrvr
If u cover the rad around the fan, u will decrease the total cooling capacity of the rad. Seems it would be a bad thing to do.

^^2

I would not expect the electric fan needs to run at highway speeds in reasonable temps with a reasonable load on an engine (and cooling system) in good condition. If anybody has this setup, can you give us your experience?

I plan to put a fan on my Townie with a relay, a thermostatic switch and an over-ride switch and an indicator light in the cab.

Dave

I have that fan setup for the Cummins in my Town Wagon. Thermostat NEVER trips fan on except when sitting idling after a hard pull, or on shutoff after a hard pull. It works fine, but I want to change to a larger fan blade & better shroud.

The shrouding is a little different effect for a hi-volume electric. It doesn't run anyway on the highway [or shouldn't] or even around town. But when it kicks in it can easily pull through the shrouding, sort of similar to a carburetor venturi section. Causes low pressure in front of radiator, pulling air through & accelerating it. Highway frontal area pressures force the air through at high velocities when fan isn't running, so that overcomes the seeming 'restriction'. I have a louvered hood on mine so air escapes very easily.

One large fan pulls far more air than 2 little ones on a given radiator surface area, assuming fan velocity & pitch are the same. If possible it's best to have a rolled lip at the fan cutout hole in shroud, reduces turbulence & increases venturi effect.