Re: Fan Cowls, 17" fan vs 14.5" fans

[Glenn Merrell <gmerrel@domain.elided>]

Hello Guy,
    Thank you for the feedback, one of the questions
that I have woken up in the middle of the night dreaming about the answer,
is the issue of 17" vs 14.5" fans.  So, I'll throw this beefsteak
into the ring....once again...
    All the Stags that I have seen fitted with the original
metal cowl have the 14.5 " plastic fans in red, yellow or white plastic. 
I believe that the 17" metal fan (actually 16.5") is actually reserved
to a small production number of exports.  If there are other owners
out there with metal fans, or having seen them on other Stags, Please
provide feedback.  I happen to have two of the metal fans, but
they are the only ones that I have ever seen.  If you take the diameter
difference, 17" - 14.5" nets 2.5 inches of free air out of a 17 inch diameter. 
It makes sence that there will be a reduced flow using the smaller fan,
but my bet is that it will be in the 10 -15 % range as opposed to numbers,
say, in the 50% range.  In any case, closing up the radiator around
either size fan will net an improvement in airflow at idle which is where
the problem lies.  If you will note from the pictures on the Cowl
site that the 17" fan takes up all the space in the cowl.  It is possible
that the 17" fan actually restricted airflow with the cowl at highway speeds,
hence netting a smaller 14.5" fan design that would work adequately at
idle and not impede airflow at highway speeds.  Of course, this goes
back to the debate of the usefulness of the cowl in cooling at all, which
I believe the UK tests show, beyond all doubt, that the cowl addition actually
allowed the temperature to stabilize at idle.  The electric fan cycling
on and off actually cooled the coolant below the limit of the thermostat
opening point.  I believe that this too could cause a problem in the
engine cooling, having the engine constantly cycling thru a wider range
of temperatures under driving and stopping....well I'll leave that one
up for the grand debat'ors.

Anyone wishing to reproduce the information on the Stag Cowl web site may do so freely.  This includes copying for newsletters, club events, publications, etc.  Since I underwent this endeavor for the love of the hobby and the car, I release copyright of the page for any Triumph related purpose.

Regards,
Glenn Merrell
"Keep Your Stag Cool, Install a NEW Composite Cowl Today"
http://pw1.netcom.com/~gmerrel/stagcowl001.html

ggrunwald@domain.elided wrote:

posted from:
        http://www2.netcom.com/~gmerrel/stagcowl001.html
from:
        ggrunwald@domain.elided
message:
        Glenn

I was not aware that larger metal fans were fitted to Stags.
My car and the ones I remember seeing in OZ have the smaller plastic fans.
I assume your cowl will not fit correctly on our cars as there would
be a large gap between the fan tips and the cowl.

Is this correct or have I misinterpreted the situation?

With your permission I am thinking of reproducing all the detail on
this site in our Triumph Club magazine.  Obviously the answer to the
question above is important to how much application the cowl will have
here.

Guy Grunwald