>From herbie ford-trucks.com Sat Oct 3 06:10:33 1998
Date: Sat, 3 Oct 1998 06:10:33 -0400 (EDT)
From: owner-perf-list-digest ford-trucks.com (perf-list-digest)
To: perf-list-digest ford-trucks.com
Subject: perf-list-digest V1 #107
Reply-To: perf-list ford-trucks.com
Sender: owner-perf-list-digest ford-trucks.com


perf-list-digest Saturday, October 3 1998 Volume 01 : Number 107



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Ford Truck Enthusiasts - Performance
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In this issue:

[none]
FTE Perf - new take on cooling
FTE Perf - VACATION
FTE Perf - new take on cooling

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Date: Fri, 2 Oct 1998 11:55:58 -0400
From: "Mr. Paul R. Boudreault"
Subject: [none]

About thermodynamics-

Here goes my two cents.

There is quite bit of information out there from a scientific point about
all of these points, most of which may have many unknown factors which are
influencing the outcome in practical applications in the "real world".

But I must say that 99% of what "Chris" has stated appears to be generally
correct. (Please do not get mad, I am not perfect either and I like to know
all or as many of the facts as possible before I make a decision. But like
the wife says "I usually wrong anyway, just ask her!")

The following is some information about "Entropy", which is a little wordy,
but is relevant. If it throws for a loop, do not worry about it, it just
explains the heat transfer process, in controlled conditions. (Such as a
closed system, like an engine cooling system.)

"By the way, (Chris), you are correct about your assumptions about water
jackets in general and cooling systems specifically. I have some pretty
neat entropy charts around somewhere. They state the second law of
thermodynamics.

1. Heat flows spontaneously from hotter to colder object, but not vice
versa.

2. No heat engine that cycles continuously can change all its input energy
to useful work.

3. If a system undergoes spontaneous change, it will change in such a way
that its entropy will increase or, at best remain constant

The second law tells us the direction a spontaneous change will follow,
while the first law tells us whether or not the change is possible according
to energy conservation.

ENTROPY (S) is a state variable for a system at equilibrium. By this is
meant that "S" (the entropy) is always the same for the system when it is in
a given equilibrium state. Like p, V, and U, the entropy is characteristic
of the system at equilibrium. When heat (Q enters a system at absolute
temperature T, the change in entropy of the system is

Delta S = Delta Q
T

provided the system changes in a reversible way. The SI unit for entropy is
thus J/K. A reversible change (or process) is one in which the values of p,
V, T, and U are well-defined during the change. If the process is reversed
then p, V, T, and U will take on the same values in reserve order. To be
reversible, a process must usually be slow, and the system must be close to
equilibrium during the entire change.

Don't you just love the "Tech. Talk"!(?) (Can't help it. It just seems to
flow out!)

There are a few other definitions of this but they say the same thing, some
are better, some are worse.


Don't overlook the "Pressure factor". Although fluids are not considered
"compressible", (and in general water in a closed cooling system in not
considered compressible), even "air" is a fluid, and is quite compressible,
as we all know. Water is compressible, although only under extreme
pressures which we do not need to normally worry about. That is why
specially designed oils are the choice in hydraulic systems, (which by the
way also develop tremendous amount of heat and the fluid must conduct the
heat transfer as part of its duties also). Water tends to "boil" off and
turn to steam at approximately 100 degrees C., or 212 degrees F, at standard
barometric pressure, (sea level). If you add pressure, you extend the range
at which water "boils". By the way without getting into more formulas, the
amount of energy required for a liquid to change states from liquid to gas
is actually tremendous and is not just a little more, or just a slight
increase in head temperature. However, the opposite is not true for some
reason, returning to liquid form is somewhat easier. (Check a physics
book.)

If you are concerned about the flow of coolant, the fact it may turn to
steam and create "hot spots" in the head, then increasing the pressure of
the system may be the answer. This however is not as easy as it sounds. A
great deal of engineering is required to design an engine and specific
clearances and torque are required to ensure proper operation. Expansion
and contraction co-efficient are calculated closely. The only obvious fix I
can see which is easy would be blueprinting the heads/block assembly to
ensure proper sealing, thus allowing a slight increase in system pressure,
hopefully enough to prevent conversion from occurring.

Also, the better antifreeze solutions available today can help also.

Better head design would have helped also, but money makes the world go
round and design factors for the average consumer are what Ford, (or any of
the car makers) consider usually. Everything is a trade off. You have to
decide what you are going to put the engine through, and design/build
accordingly.

Anything can be accomplished, if your willing to throw enough money at the
problem. (But where does a reasonable person say enough?)

Sorry for the long post, but this is really interesting stuff, and I really
enjoy all the points of view that I see on this.

Mr. Paul R. Boudreault
Retired RCAF/CAF

79 Ford Bronco, 351M, 4BB, 4 speed Manual, Balanced & blueprinted, all heavy
duty parts, body & suspension being restored/rebuilt.

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Date: Fri, 2 Oct 1998 15:31:48 -0400
From: Sleddog
Subject: FTE Perf - new take on cooling

got it from someone who's experience and knowledge i highly respect, that
without the t-stat, it isn't as much the flow through the engine that is
too fast, but rather the flow through the radiater. the radiater can't
dissapate the heat fast enough. this is supported by some reading i did in
some older books (like the '50s).

sleddog

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Date: Fri, 2 Oct 1998 16:22:45 -0400
From: am14 chrysler.com
Subject: FTE Perf - VACATION

Azie will be on vacation the week beginning 10/5/98. Going to Maui Hawaii.
Drool !! Drool !!

That is why it was absolutely necessary to get my vision corrected last
week . Couldn't afford to miss the "scenery".

I will be unsu*scribing from the lists.
Will resu*scribe upon returning to work.

Azie
Ardmore, Al


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Date: Fri, 2 Oct 1998 14:05:38 -0700
From: George
Subject: FTE Perf - new take on cooling

got it from someone who's experience and knowledge i highly respect, that
without the t-stat, it isn't as much the flow through the engine that is
too fast, but rather the flow through the radiater. the radiater can't
dissapate the heat fast enough. this is supported by some reading i did in
some older books (like the '50s).

sleddog

That's the definition I've always heard and believed. As mentioned,
emission requirements have pushed manufacturers into running the current
generation of gas engines at what I consider very hot temps in an effort to
aid combustion efficiency. The aux cooling fans on most don't engage until
reaching a sending unit temp of 225 degrees, which can put actual engine
temps close to the edge.

As an example, a friend's Toyota 4x4 p/u started overheating to the red
portion of the sensor idiot gauge. Wouldn't run cool no matter what. We
replaced the thermostat and it was back to normal. The small size of the
radiator, without a thermostat to hold the coolant/water mixture in it long
enough to dissipate the heat, was unable to cool the engine on a continuous
flow basis.

On the other hand, If you've ever looked at the size of a truck radiator
and open space in the engine bay, you can understand why no thermostat can
keep the engine running temp too cool for proper combustion heat. That's
why 18 wheelers can idle 24 hours or pull grades in lower gears in 110+
temps with a/c and other power options operating full blast.

George Miller


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End of perf-list-digest V1 #107....


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