[DeTomaso] Single or Dual Pass Radiators?

[B. Seib]

Theory aside, it does seem that either single pass or double pass types can
be made to work acceptably in a Pantera as long as the rest of the system is
in good shape and compliments the choice of radiator. I suspect the double
pass system may reach its limitation sooner in racing situations and high HP
at high temps.
Barry
  -----Original Message-----
  From: mark skwarek [mailto:ehpantera at yahoo.com]
  Sent: Monday, June 13, 2011 11:47 PM
  To: 'B. Seib'; Charles Engles
  Cc: detomaso at realbig.com
  Subject: Re: [DeTomaso] Single or Dual Pass Radiators?


        I have a Griffin radiator with two rows of 1.5" cores. 3" thick
total. Griffin has this type of radiator rated for 600 to 1000HP. It is a
single pass type and I have never had any problems with over heating.  I am
using a 190 degree thermostat.

        Mark

        --- On Mon, 6/13/11, Charles Engles <cengles at cox.net> wrote:


          From: Charles Engles <cengles at cox.net>
          Subject: Re: [DeTomaso] Single or Dual Pass Radiators?
          To: "'B. Seib'" <oldwheel at shaw.ca>
          Cc: detomaso at realbig.com
          Date: Monday, June 13, 2011, 11:31 PM


          Dear Barry,


                     Even after going through over 900 track photos, your
succinct
          summary of coolant basics makes sense and explains why the dual
and triple
          pass radiators don't seem to work in Panteras as well as they are
expected.



                               Warmest regards,  Chuck Engles




          -----Original Message-----
          From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com] On
          Behalf Of B. Seib
          Sent: Monday, June 13, 2011 6:44 PM
          To: DetomasoList; Ken Green
          Subject: [DeTomaso] Single or Dual Pass Radiators?

          Ken
          This has been discussed to death several times before and
agreement of all
          parties was never achieved.
          My opinion based on an analysis of The views I trusted most was
that a dual
          pass may have some small advantage in an idling/ traffic situation
and the
          single pass was better at high speed/load/HP. If you believe the
"more flow
          is better" theory, it's single pass. If you buy the theory that
coolant
          needs to spend a long time in the rad to shed more heat, maybe
dual or
          triple pass is for you.
          Barry


          Stewart Components and Evans Coolant are  "more flow is better"
advocates:

          http://www.stewartcomponents.com/tech_tips/Tech_Tips_5.htm

          http://www.stewartcomponents.com/tech_tips/Tech_Tips_3.htm

          quoting Stewart>>>>


          Double pass radiators require 16x more pressure to flow the same
volume of
          coolant through them, as compared to a single pass radiator.
Triple pass
          radiators require 64x more pressure to maintain the same volume.
Automotive
          water pumps are a centrifugal design, not positive displacement,
so with a
          double pass radiator, the pressure is doubled and flow is reduced
by
          approximately 33%. Modern radiator designs, using wide/thin cross
sections
          tubes, seldom benefit from multiple pass configurations. The
decrease in
          flow caused by multiple passes offsets any benefits of a high-flow
water
          pump.


          A common misconception is that if coolant flows too quickly
through the
          system, that it will not have time to cool properly. However the
cooling
          system is a closed loop, so if you are keeping the coolant in the
radiator
          longer to allow it to cool, you are also allowing it to stay in
the engine
          longer, which increases coolant temperatures. Coolant in the
engine will
          actually boil away from critical heat areas within the cooling
system if not
          forced through the cooling system at a sufficiently high velocity.
This
          situation is a common cause of so-called "hot spots", which can
lead to
          failures.

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