How to make a fan shroud:
Cut a long strip of sheet metal (length roughly based on circumference of
fan), leaving 3 or 4 short protruberances or tabs along one side.
Drill small hole in each tab. Bend tabs at right angles to strip. Bend strip
into loop and fasten to radiator with ties through tab holes.
BTW, another benefit of the shroud is that otherwise a lot of the fan's
energy is wasted stirring up the rest of the air in the engine compartment.
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
on 8/5/05 12:15 PM, Barrie Robinson at barrie@look.ca wrote:
> I have been told that I must shroud my electric puller fan to get
> engine/engine bay temp down but I am having trouble understanding the
> physics of this. I know shrouding is always done on new cars so one would
> suspect that they know what they are doing.
>
> If one considers a fan stuck in front of a rad it seems reasonable to
> suppose it pulls air in through the rad in a profile almost exactly as its
> fan blade coverage. Thus the rad not covered by the fan just has air
> pushed over it by normal car motion. In other words how can the electric
> fan, humping away pulling air through the rad core directly in front of it,
> effect the flow of the non-covered area? What must happen is that the
> shroud forces air to be pulled through the non-fan blade covered areas at a
> FASTER rate than if they were left alone. This points to the need for a
> sufficiently powerful electric fan. So I suppose I should make a
> shroud. Does anyone know how to make a shroud for a D&D Fabrications heavy
> duty rad and a Perma-Cool 19114 14" fan?
>
> Regards
>
> Barrie Robinson
> barrie@look.ca
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