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Cooling

To: <morgans@autox.team.net>
Subject: Cooling
From: "William Eastman" <william.eastman@medtronic.com>
Date: Tue, 09 Jan 2001 11:38:55 -0600
A few comments from left field

Aluminum radiators are less efficient than copper, not more.  A new
aluminum radiator cools better because it is new and because the new,
ultra-wide tubes, are more efficient. On our cars, the individual
coolant tube are about 3 or 4 times as deep as they are wide.  On
moderns, this ratio is near double that.  A higher ratio gives more
surface area for exchanging heat.  I have never seen a copper core with
these ultra-wide tubes but, if one were built, it would be really
efficient.

For traditional radiators, 4 to 5 rows is about as thick as you can go
and still get more efficient.  Old English cars complicate this a bit
since they used a different design (v-cell?) than US radiators.  The
British design is a bit more efficient than what radiator shops use
today.  So, if you recore your original radiator without adding rows,
you actually loose cooling capacity.  

Fewer, longer tubes between tanks are less efficient than more, shorter
tubes.  The reason for this is simple.  By the end of a long tube, the
coolant is cooler.  Since heat transfer is driven by temperature
differences, the ends of long tubes don't reject much heat.  You are
better off with lots of short tubes.  has anyone ever built a cross flow
Morgan radiator?

The radiator cap holder is easily removed from your radiator.  Most
older British cars use a longer-reach radiator cap than more modern
iron.  Any competent radiator shop can swap out the older cap holder for
one that takes the shorter cap.  this will allow you to pick up a new,
recovery-friendly cap at K-Mart rather than searching old NAPA parts
books.  

If your overheat at idle, add more fans.  If your overheat at speed,
fans won't help.  You need to either manage gross airflow or add cooling
capacity.

Last but not least, factory specs for our old cars were developed when
good fuel was scarce.  If you overheat first try advancing the timing. 
This converts more energy to power and less to heat your radiator has to
deal with.  Also, when you rebuild, remember that a tight engine makes
heat while a loose engine makes power.  

In case of emergency, remember our airborne friends.  Many high
performance aircraft are run very rich since any extra fuel that doesn't
burn helps cool the engine.  If you are in the middle of nowhere and you
can't keep your car cool, turn up the mixture and plug your nose.  

Have fun,
Bill
Who doesn't have to worry about anything overheating for a few months.

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