[DeTomaso] Single or Dual Pass Radiators?

[B. Seib]

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.