[DeTomaso] gumball pantera purging air from cooling system

Mon Oct 17 10:31:19 EDT 2011

Here's some more info.

*14 Rules for Improving Engine Cooling System Capability in High-Performance
Automobiles*
*Produced by the National Automotive Radiator Association (NARSA) and by
Richard F. Crook, Transpro, Inc.*

It’s not unusual for automobile enthusiasts to want to increase the power of
the engine in their automobiles and many aftermarket options are available
to them to accomplish this.  Increasing the engine horsepower then presents
the problem of making sure that other components of the vehicle, such as the
drive train and the cooling system, can handle the increased engine power.

Small increases in engine power can usually be accommodated by the original
drive train and cooling system, since there is usually some safety factor
designed in and because the vehicle will not always be driven under the
worst conditions or highest temperatures, Larger increases in engine power
may require modifications to improve the performance of the other vehicle
systems, particularly the cooling system.

There are actually many popular misconceptions regarding the heat transfer
performance of an engine cooling radiator. Because many of the more common
of these misunderstandings may actually reduce cooling performance rather
than improve it, some clarification is required.

*Effect on the Cooling System of Increasing Engine Horsepower*

It’s helpful to understand that, during operation, internal combustion
engines convert the energy of fuel into mechanical work and heat.
Approximately one-third of the fuel energy goes into the mechanical work of
the moving vehicle, one-third into exhaust heat, and one-third into heat
transferred by the engine cooling system to the ambient air.

 This means that heat load to the cooling system at rated power (Usually
expressed in BTUs per minute) is approximately equal to the rated power of
the engine expressed in BTUs per minute (HP X 42.4 = BTU/minute). From this
we can see that if an engine is modified to increase its horsepower, the
load to the cooling system will also increase. In fact, the heat load to the
cooling system will increase by about the same percentage as the increase in
engine horsepower.  So, if we increase the engine horsepower by 20 percent,
we can expect an increase of about 20 percent in the heat load to the
cooling system.

 *The Major Factor Governing Cooling System Heat Transfer*

 Cooling system heat transfer is governed by a single major factor-the heat
load to the cooling system.  Under “steady-state” conditions, the heat load
to the cooling system (the heat rejected by the engine to the cooling
system) will be transferred to the cooling air by the radiator no matter how
good or how poor the radiator.  So, if both a “poor” radiator and a “good”
radiator will both transfer the same heat load to the cooling air, how can
we say that one radiator has better heat transfer performance than the
other?  The answer is that, under “steady-state” conditions, with a “good”
radiator in the cooling system, the radiator inlet temperature (Radiator top
tank temperature) will stabilize at a lower temperature than a “poor
radiator” in place.  The “poor radiator may be so poor that its coolant
temperature may rise to the boiling point resulting in engine overheating.

*Temperature Differential*

The difference between the radiator average core temperature and the
temperature of the cooling air is the driving force behind the transfer of
heat from the coolant to the cooling air.  When an engine starts and is run
up to rated load, the coolant begins to heat up.  When there is no
thermostat in the system, the coolant flows from the engine through the
radiator and back to the engine.  Initially, the coolant and metal in the
engine absorb the heat being produced and continue to do so until the
temperature of these parts exceeds the cooling air temperature.  At this
point, heat transfer to the cooling air commences.  The coolant temperature
continues to rise until it reaches a temperature at which the difference
between the radiator average core temperature and the incoming cooling air
is great enough to transfer the entire heat load to the air. This then
becomes a “steady-state” condition.

*Heat Load to the Cooling System*

The heat load to the cooling system is related to the flow through the
radiator and the temperature drop through the radiator by the following
expression:

*Q = M * cp *dT*

Where Q is the heat load BTU/min., M is the mass flow rate of the coolant in
BTU per pound per degree F, dT is the temperature drop through the radiator
in degrees F, and * indicates multiplication. Since a gallon of coolant
weighs about 8.3 pounds, we can replace M in the expression by 8.3 times the
coolant flow in gallons per minute, or GPM.  The resulting expression is as
follows:

*Q  =  8.3 * GPM * cp * dT*

Since the specific heat of the coolant is essentially constant and the
coolant flow rate

is constant at rated engine speed, the expression tells us something that
surprises most people. That is, for a given heat load and coolant flow rate,
the coolant temperature drop through the radiator will be constant, and
nothing anyone can do to the design of the radiator can change that. Adding
rows or fins or face area or whatever will not change the temperature drop
through the radiator.  As a general rule, cooling systems are designed to
operate with a coolant temperature of about 190 degrees F at the radiator
inlet and have about a 10 degree F temperature drop through the radiator at
rated power and rated coolant flow.  This will result in a bottom tank
temperature of 180 degrees F.  Note that the coolant temperature drop

 through the radiator must be specified in degrees F or degrees C, not
percent.  Taking a percentage of the radiator inlet temperature will yield
different results depending on whether the inlet temperature is given in
degrees F or degrees C.

 *Effects of Radiator Design on the Cooling System*

 A cooling system whose heat load and coolant flow rate results in a 10
degree F coolant temperature drop through the radiator will have that same
coolant temperature drop whether the radiator has a very small face area and
flat fins or a very large face area and louvered fins.  The difference is
that the large louvered fin radiator will be more effective than the small
radiator at transferring heat to the cooling air, meaning that it can do it
with a much lower difference in temperature between the core and cooling
air.  The small radiator may require such a high difference in temperature
between the core and the cooling air and the core that the coolant may reach
boiling temperature before the core is able to transfer all of the heat load
to the cooling air.  While both radiators would have the same coolant
temperature drop through the radiator, we would say that the larger radiator
had better heat transfer performance if its top tank temperature (Inlet
coolant temperature) stabilized at, say, 180 degrees F while the smaller
radiator stabilized at 220 degrees F.

 *Improving an Overheated Cooling System*

 Armed with this understanding of how a cooling system works what
recommendations should we make for a cooling system that is overheating?
Suppose we have an engine and cooling system that, in stock condition,
produced a rated 200 hp and ran at rated ambient temperature with a top tank
temperature of 190 degrees F and a 10 degree F temperature drop through the
radiator.  Now suppose the engine were modified to produce 240 hp, a 20
percent increase.  We would find that at 240 hp the core temperature drop
had increased by 20 percent to 12 degrees F and the top tank temperature had
increased, let’s say to the point where it was just overheating.  Now
suppose we take this system and reduce the power to the point where the
radiator inlet, or top tank temperature is steady at 190 degrees F.  (Guess
what?  It’ll be producing 200 hp!  Funny, how that works). So we check
coolant temperature drop and find it is back to 10 degrees F, as we would
expect, meaning the average core temperature is 185 degrees F.  Now we want
to make improvements to the system in order to lower the top tank
temperature to the point where we can then go back to 240 hp without the
engine overheating.

 *Coolant Flow Rate*

 Looking at the previous expression, we can see that slowing the coolant
down is the wrong way to go.  If the heat load is constant, lowering the
flow will increase the temperature drop through the radiator, making the
bottom tank, or radiator outlet, temperature less than before. If the bottom
tank temperature goes down, the top tank temperature must go up to maintain
approximately the same average core temperature so that the heat load may be
transferred to the cooling air.  At the reduced power setting it would rise
above 190 degrees F and at 240 hp the engine would be overheating worse than
before.  In fact, because the lower flow rate results in lower coolant
velocity and less “scrubbing action” in the tubes, the average coolant
temperature must rise slightly in order to transfer the heat load from the
coolant to the cooling air, making matters even worse.

What would happen if we increase the coolant flow?  Will it go through the
radiator so fast that there won’t be time for cooling to take place?  Not at
all, from the expression, we can see that if the heat load is constant,
increasing the coolant flow rate will reduce the coolant temperature drop
through the radiator, resulting in a higher bottom tank temperature.  If the
bottom tank temperature is increased, the top tank temperature must go down
to maintain approximately the same average core temperature.  This is what
we were hoping to achieve.  With the top tank temperature now less that 190
degrees F at the reduced power point, we can expect  that the system will be
better able to run at 240 hp without overheating,  In fact,  because  the
increased coolant flow rate results in a higher coolant flow velocity and
better “scrubbing action” in the tubes, the average coolant temperature
decreases slightly while transferring  the same heat load to the cooling
air, further lowering the top tank temperature, resulting in better cooling
performance.

>From this we see that increasing the coolant flow rate will result in better
heat transfer performance.  There are some cautions to be observed in
increasing coolant flow rate, however.  Going too far may result in aeration
and foaming of the coolant, possible damage to the radiator by overpressure,
cavitation of the pump, due to excessive pressure drop through the radiator,
and erosion of the radiator tubes.  The ideal coolant flow rate is one that
will provide optimum coolant flow velocity through the radiator tubes in the
range of 6 to 8 feet per second.  Flow velocities above 10 feet per second
should be avoided.

*- IMPROVEMENT RULE # 1 -*

*Anything you can do to increase the coolant flow rate, within limits
described, will improve heat transfer and cooling performance.  Anything you
do to restrict or reduce the coolant flow rate will hurt cooling performance
*

*Cooling Airflow*

 Cooling air becomes heated as it passes through the radiator.  It enters
the radiator at ambient temperature and exits the radiator at some increased
temperature.  It is the difference between the average core, or coolant
temperature and the average of these two cooling air temperatures that
creates the ability of the radiator to transfer heat to the air.  The slower
the air passes through the radiator, the higher will be its exit temperature
and the higher will be the average cooling air temperature.  The higher the
average cooling air temperature, the less heat will be transferred from the
coolant to the air.  On the contrary, the faster the air flows through the
core, the less it will increase in temperature on its way through, making
the exit temperature and the average cooling air temperature lower.  This
increases the differential between the average core temperature and the
average air temperature, increasing the heat transfer.  Increasing airflow
by speeding up the fan, by providing an improved fan, by providing or
improving the fan shroud, by reducing air restrictions in the grille or
engine compartment, or by providing recirculation shields to prevent air
from bypassing the core, will all improve heat transfer and cooling.

*-Improvement Rule #2-*

*Anything you can do to improve airflow through the radiator core will
help.  Anything that blocks or slows airflow, either before or after the
radiator, will hurt.*

*Radiator Face Area*

As we have seen, cooling air becomes warmer as it passes through the
radiator. Coolant in the back row of a radiator is cooled by warmer cooling
air that coolant in the front row of a radiator. Increasing the face area of
a radiator exposes more coolant to the coolest ambient cooling air,
increasing the radiator heat transfer capability.

Increasing the radiator face area may not be practical in all cased because
of space limitations.  However, similar improvement may be obtained by
relocating any air conditioning condenser, or oil cooler which may be in
front of the radiator, thereby exposing more of the face area of the
radiator to the coolest ambient cooling air.

*-Improvement Rule- #3*

*Increasing the face area of the radiator by making the radiator larger will
help.  Relocating other heat exchangers that were in front of the radiator
in order to expose more radiator face area to ambient cooling air will also
help.*

*Radiator Fins*

Increasing the radiator fin count, or number of fins per inch, provides more
surface area for the transfer of heat to the cooling air.  However,
increasing the fin count increases the restriction of the radiator to
cooling airflow.  Lower cooling airflows result in lower heat transfer.  In
every installation there is an optimum combination of fin performance and
core restriction that will produce maximum heat transfer.  Increasing the
core restriction from this optimum point by increasing fin count will reduce
the heat transfer performance of the radiator.  On the other hand, if the
original radiator has a very low fin count, increasing will improve heat
transfer.  In general, for high performance applications, fin counts from 12
fins per inch to 16 fins per inch are optimum.  Increasing the fin count
above 16 fins per inch will almost always result in reduced heat transfer
performance.  Since, as we have seen, in a given installation under
“steady-state” conditions the radiator must transfer the given heat load no
matter what, the reduced heat transfer performance resulting from an
excessively restrictive high fin count must be compensated for by increased
coolant temperature, possibly to the point of overheating.

Radiators may be made with plate fins.  In this case, the tubes are inserted
through stacks of relatively flat fins that have tube holes in them.  The
tube holes in the fins have collars on them which help to provide the solder
or braze bond between the fins and tubes.  These collars tend to limit the
fin spacing to a maximum of about 13 fins per inch.

Radiators may also be made with serpentine fins.  In this case, rows of tube
are stacked with layers of corrugated fins.  The fins become bonded to the
tubes where the tips of the fin convolutions touch the tubes during solder
baking or brazing.  Soldered plate fin radiators are usually structurally
stronger that soldered serpentine radiators and are more expensive to
manufacture.  Brazed serpentine radiators are usually stronger structurally
that nay soldered radiator.

Radiator fins, whether plated or serpentine types, may be louvered or
non-louvered.  Louvered fins turbulate the air passing through the radiator
to increase the “scrubbing action” of the cooling air, providing greatly
improved heat transfer with some increase in air restriction.  Louvered fins
also tend to become clogged with dust and debris more readily than
non-louvered fins, but for high performance applications are the only way to
go.  Non-louvered fins are typically used on farm and construction
equipment, operating in dirty environments.  Non-louvered fins may be made
with patterns of dimples, waves, or bumps in order to provide turbulation
without clogging.

*Core Depth and Number of Rows of Tubes*

*-IMPROVEMENT RULE- #4*

*Increasing the fin count may help, but it may hurt.  Increasing the count
above 16 fins per inch will almost always hurt.*

*-IMPROVEMENT RULE- #5*

*A plate fin radiator and a serpentine fin radiator of the same fin count,
tube size, tube rows, face area, core depth, etc., will have the same heat
transfer performance.  However, serpentine fin radiators can be made with
higher fin counts, sometimes resulting in improved performance.*

* -IMPROVEMENT RULE-#6*

*Louvered fins provide greatly improved heat transfer with some increase in
cooling air restriction.  Changing from a non-louvered radiator to a
louvered radiator core almost always improves heat transfer performance.*

* *

* *As we have discussed, cooling air becomes warmer as it travels through
the radiator core.  Each successive row of tubes becomes cooled by warmer
and warmer cooling air until at some point little or no heat transfer takes
place.  As was discussed regarding fin count, in every installation there is
an optimum combination of fan performance and core restriction that will
produce maximum heat transfer performance.  Increasing the core restriction
from this point by increasing the number of rows of tubes will reduce the
heat transfer performance of the radiator.  However, if there is a high rate
of cooling airflow through the core, adding a row of tubes will probably
provide some improvement. In high performance applications with louvered
fins, three rows or a maximum of four rows will probably provide best
performance.  Increasing beyond four rows in a louvered core will provide
little or no improvement and may even result in reduced performance.

Adding another row of tubes has other effects.  It provides another path for
the coolant, resulting in lower coolant flow velocities through the tubes.
Optimum coolant flow velocity through the radiator tubes is about 6 to 8
feet per second.  If the flow rate becomes low enough, laminar flow occurs,
creating a boundary layer of coolant along the walls of the tubes. This
boundary layer, or very slowly moving layer of coolant, acts as an insulator
and retards heat transfer.  Going to a smaller tube size when adding a row
of tubes is one way to keep the coolant flow rates up in the tubes to help
prevent the formation of a boundary layer.  Another way is to use dimpled
tubes, which are commonly used in low flow applications.

Contrary to popular opinion, dimpled tubes do not slow the coolant down in
order to make it stay in the tubes longer.  The dimples increase the length
of the coolant flow path by making the coolant twist and turn as it passes
through the tube.  This actually speeds up the coolant flow along the tube
wall, increasing its “scrubbing action,” preventing the formation of a
boundary layer, and improving heat transfer.  On the other hand, using
dimpled tubes when they are not needed can hurt heat transfer performance by
increasing tube restriction, which reduces coolant flow and can cause
cavitation at the coolant pump.

-IMPROVEMENT RULE- #7

*Adding a row of tubes may help, but it may hurt by increasing cooling air
restriction and reducing the coolant flow rate in the tubes.  If the cooling
airflow has been increased over the original installation, adding a row or
two will probably help in this situation. Increasing the number of rows
beyond 4 in a louvered fin core will almost always hurt.*

*-IMPROVEMENT RULE- #8*

*Adding two rows of tubes without increasing the coolant flow rate (Bigger
pump or turning the old pump faster) will probably reduce performance
because of low coolant flow rate in the tubes.  Reducing the tube size or
going to dimple tubes may help. Increasing the coolant flow rate will surely
help.*

 *Coolant Selection*

* *Water has a higher specific heat than an ethylene glycol or propylene
glycol coolant mix. Therefore, it provides the best heat transfer
performance in a cooling system.  If a cooling system is marginal, that is,
it only overheats on the hottest of days, then running with water as a
coolant in the summer and an ethylene glycol or propylene glycol coolant
solution during the rest of the year will probably solve the problem.
Commercial coolant solutions provide cooling, anti-freeze protection,
corrosion inhibitors to protect the metals in the cooling system, and a
lubricant for the water pump.  When running water as a coolant for maximum
heat transfer, a product that provides a corrosion inhibitor and water pump
lubricant should be added to the water.

 In terms of the relative heat transfer performance of ethylene glycol
versus propylene glycol coolant bases, they are pretty much equal when mixes
according to the manufacturers’ recommendations, usually a 50/50 water to
glycol mix. Ethylene glycol coolant solutions provide slightly higher heat
transfer performance over propylene glycol solutions at low coolant flow
rates.

*-IMPROVEMENT RULE- #9*

*For maximum heat transfer performance in warm climates, use water as a
coolant with an additive to provide a corrosion inhibitor and water pump
lubricant.  For winter service, use a 50/50 water to ethylene glycol coolant
solution that includes corrosion inhibitors and a pump lubricant.*

*Aluminum vs. Copper/Brass Radiators*

* *Copper is a better conductor of heat than aluminum.  Copper/brass
radiators usually have copper fins, but brass tubes (70% copper, 30% zinc).
The bond between the fins and the tubes may be made with soldier (A tin/lead
alloy, or high-tin alloy) or with a braze material (mostly copper).

On Mon, Oct 17, 2011 at 10:26 AM, michael at michaelshortt.com <
michaelsavga at gmail.com> wrote:

> I will research the mixture question before I offer an opinion on the
> difference in temps making a difference in the ratio.
> My mixture was a result of research based on optimum cooling and
> heat dispersion.
>
> I filled at level, let it run, then cut it off, jack it up and started the
> whole process I told you about.
>
> I did not jack up the front, that seems counterproductive to me, any
> trapped air has no place to go.
>
>
>
> On Mon, Oct 17, 2011 at 10:20 AM, <LEVITT1946 at aol.com> wrote:
>
>> **
>> I think I need more antifreeze being in New York. Winter is coming so
>> below freezing weather is just around the corner .
>>
>> 33/67 does not give me much freezing protection.
>>
>> Did you raise the rear of the car when filling ? After filling did you
>> raise the front of the car as well?
>>
>> Bob
>>
>>  In a message dated 10/16/2011 11:34:16 P.M. Eastern Daylight Time,
>> michaelsavga at gmail.com writes:
>>
>> 33% anti freeze, 67% water.
>>
>> i filled mine up, let it run while up in the air with the tank lid off,
>> waited for the thermostat to open, topped it off unitl it overflowed, , then
>> capped it, lowered the car. turned it off. let it cool. opened up the tank,
>> added more, let it run until it opened again, topped it off. capped it.
>> turned it off.  Haven't touched ot since.
>>
>> Michael
>> On Oct 16, 2011 9:57 PM, <LEVITT1946 at aol.com> wrote:
>>
>>> **
>>> WHAT IS  33AF/67
>>> RADIATOR IS ONE YEAR OLD
>>> RADIATOR IS CLEAN
>>> YES I JACKED THE CAR UP IN THE REAR .
>>>
>>> AFTER IT IS FILLED SHOULD YOU JACK UP THE FRONT AS WELL?
>>>  In a message dated 10/16/2011 1:32:56 P.M. Eastern Daylight Time,
>>> michaelsavga at gmail.com writes:
>>>
>>> I went through all of this in the last year, IMHO you have air in your
>>> system, your 50/50 mix should be 33af/67 distilled water and water wetter.
>>> How old in the radiator?  Has it ever been cleaned?  Do you fill it and run
>>> it with the rear end jacked up at least 15"?
>>> After having mine boiled, the mix above installed and de airred.  I can
>>> sit in traffic on a 100 degree day At 170 and run it hard and never cross
>>> 185.  Prior to that, i was constantly above 200, 220 in traffic and to wary
>>> to push it.
>>>
>>> Michael
>>> On Oct 16, 2011 12:46 PM, <LEVITT1946 at aol.com> wrote:
>>>
>>>> Dear Friends,
>>>>
>>>>
>>>> My Cooling system is set up as follows;
>>>>
>>>> fluidyne radiator leaning forward
>>>>
>>>> sucker fans on ALL the time
>>>>
>>>> Antifreeze  50/50 blend
>>>>
>>>> New High Flow Water pump
>>>>
>>>> 160 thermostat( correct for cleveland)
>>>>
>>>> I Used this tool to suck all air out of system and put the  antifreeze
>>>> back
>>>> in:
>>>>
>>>> UView 550000 Airlift Cooling  System Leak Checker and Airlock Purge Tool
>>>> Kit
>>>>
>>>>
>>>> On the open road the car runs at a  steady 180. As soon as I get into
>>>> stop
>>>> and go traffic or go from waiting at red  lights I can see the temp
>>>> gauge
>>>> start climbing 220 plus . In the heat  of the summer months I feel like
>>>> the
>>>> car is ready to blow  hoses.
>>>> I have read that guys here in the  group have cars that sit in the
>>>> desert
>>>> sun all day and the temp gauge barely  moves. Either their gauges are
>>>> broken
>>>> or I have a system that the antifreeze is  just not flowing and cooling
>>>> .When I bought the car three years ago the guy  said," If you are caught
>>>> in
>>>> traffic ,just pull over". I refuse to believe that  Detomaso designed
>>>> the car to
>>>> overheat. I see Ferrari's,Lambo's and  Porsche run cool.So why can't the
>>>> Pantera?
>>>> I told my high temp issues to a  guy last week at one of the cruise in's
>>>> and he said to me that back in the 70's  and 80's he developed a system
>>>> that
>>>> would lower the cooling temp by at least 20  degrees. He said that the
>>>> cleveland engine in a pantera leans down at the  firewall and the heads
>>>> will
>>>> always get air trapped at the rear of the  head.(back of car) Causing
>>>> there
>>>> airlock situation and therefore  restricting flow.
>>>> What he does is drill a hole  into each head and runs stainless lines to
>>>> the pressure tank or  the the overflow tank,I forgot which one.
>>>> Does this make sense to anyone ? Has  anyone every done this and had
>>>> success?
>>>> This guy did not seem like a typical  back yard mechanic .He designed
>>>> this
>>>> process while he was working for a speed  shop out here in New York
>>>> called
>>>> Motion.
>>>> Please let me know your thoughts  .
>>>> Regards,
>>>> Bob Levitt
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>>
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>>>>
>>>
>
>
> --
>
>
>
>
>
>
>
> Michael L. Shortt
> Savannah, Georgia
> www.michaelshortt.com
> michael at michaelshortt.com
> 912-232-9390
>
>
> This email is protected by the Electronic Communications Privacy
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-- 

Michael L. Shortt
Savannah, Georgia
www.michaelshortt.com
michael at michaelshortt.com
912-232-9390

This email is protected by the Electronic Communications Privacy
Act, 18 U.S.C. Sec. 2510-2521, is confidential and may be legally
privileged.  If you are not the intended recipient, you are hereby notified
that any retention, dissemination, distribution or copying of this
communication is strictly prohibited.  Please reply to the sender that you
have received this message in error, then delete it.  Thank you