Hoyt wrote:
>On Sunday 23 October 2005 02:00 pm, Dave1massey@cs.com wrote:
>
>
>>In a message dated 10/22/2005 10:47:19 PM Central Standard Time,
>>
>>hoyt@cavtel.net writes:
>>
>>
>>
>>>It also surprises me that no one has mentioned constructing a radiator
>>>fan shroud. That would certainly be cheaper and more efficient than an
>>>electric pusher fan and, again, aluminum or PVC sheet - the latter easily
>>>heat-shaped
>>>
>>>around a box form - would work well.
>>>
>>>
>>Do you mean a shroud that couples the back side of the radiator to the fan
>>so that the fan air must pass through the radiator rather than around it?
>>
>>
>
>Kind of. It's a box on the back of the radiator that has a hole only large
>enough for the fan blade. The relationship of the fan blade to the edge of
>the shroud is important (not too deep or to far away). It actually improves
>the efficiency of the fan at slow road speeds, but may cause some at higher
>road speeds.
>
>Here's a link with a picture:
>http://www.yogisinc.com/Detail.cfm/-/Product_CD=CCI-70/Brand=98/product.htm
>Note the lower left and right corners where a flexible vent has been added to
>allow air at high road speeds (higher pressure) to exit the shroud to solve
>that problem. I believe they are called "relief windows".
>
>Here's another link that shows a shroud only. IIRC, these can be obtained in
>various dimensions without a pre-cut hole.
>http://littlejoesrodshop.com/walker1.htm
>
>They don't look too difficult to fabricate out of black 1/8" PVC sheet goods.
>
>
Triumph always used a front-side shroud on the TR-2s and -3. They used
a back-side shroud on the -4s and 6s. Both simply formed an "air
tunnel" so that all the air flow went through the whole radiator, not
just the space covered by the fan.
Other manufacturers, such as BMW use back-side shrouds that only allow
air through the cross section of the fans. From experience, I can tell
you that if you leave this out, you better have a good, strong auxillary
fan when the weather is hot, or driving is slow!
Cheers.
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