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Interesting article Bob but IMHO their statement:
"Pressure in a cooling system is vital for keeping water in contact with the
metal surfaces of the cylinder heads and block."
is something of an over simplification.
The reality is that any "boiling " of the coolant produces a "bubble" of
gaseous coolant, there is no air, as such, involved.
Their statement :
"Pressure keeps the air compressed and maintains the water-to-metal
contact. "
suggests that the cooling system contains air; it shouldn't contain any
air, other perhaps the very small quantity disolved in the coolant.
Pressurizing the cooling system raises the boiling point. Raising the
boiling point means that the temperature of the engine surfaces where
gaseous coolant will be generated will also need to be higher for boiling
to occur.
As the rate of heat radiation from the cooling surfaces is proportional to
the 4th power of the absolute temperature there is also a considerable
increase in the amount of energy that can be dissipated by the radiator.
These things together make pressuring the cooling system even to only 7
p.s.i. very advantageous.
As I mentioned earlier the problem with the 100 insofar as cooling system
pressure is concerned is the carbon seal in the water pump and perhaps the
design of the radiator tanks.
M
On Thu., Feb. 24, 2022, 10:42 a.m. Bob Spidell, <bspidell@comcast.net>
wrote:
> I was about to jump in and say "But, but, but .... pressure only raises
> the boiling point but, for once, I did some 'research' first:'
>
> "Pressure in a cooling system is vital for keeping water in contact with
> the metal surfaces of the cylinder heads and block."
>
>
> https://www.motortrend.com/how-to/understanding-the-cooling-system-cool-under-pressure/
>
>
> On 2/24/2022 7:01 AM, john harper via Healeys wrote:
> > Alan
> >
> > Many A90 Atlantics suffered overheating. The club developed a fairly
> > simple adapter that screwed in place using the thread of the normal
> > cap on the outside to which a shape of a 7 psi AH100 pressurized cap
> > fitting was added. It improved the engine cooling in many of the cars
> > that were prone to boiling over.
> >
> > Best regards
> >
>
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Content-Transfer-Encoding: quoted-printable
<div dir=3D"auto"><div dir=3D"auto">Interesting article Bob but IMHO their =
statement:=C2=A0<div dir=3D"auto"><span style=3D"font-size:12.8px">"Pr=
essure in a cooling system is vital for keeping water in contact with t</sp=
an><span style=3D"font-size:12.8px">he metal surfaces of the cylinder heads=
and block."</span><br></div><div dir=3D"auto">is something of an over=
simplification.=C2=A0<span style=3D"font-size:12.8px"><br></span></div><di=
v dir=3D"auto">The reality is that any "boiling " of the coolant =
produces a "bubble" of gaseous coolant, there is no air, as such,=
involved.=C2=A0</div><div dir=3D"auto">Their statement :</div><div dir=3D"=
auto">"Pressure keeps the air compressed and maintains the water-to-me=
tal contact. "<br></div><div dir=3D"auto">suggests that the cooling sy=
stem contains air; it shouldn't contain any air, other perhaps the very=
small quantity disolved in the coolant.</div><div dir=3D"auto">Pressurizin=
g the cooling system raises the boiling point. Raising the boiling point me=
ans that the temperature of the engine surfaces where gaseous coolant will =
be generated will also=C2=A0 need to be higher for boiling to occur.</div><=
div dir=3D"auto">As the rate of heat radiation from the cooling surfaces is=
proportional to the 4th power of the absolute temperature there is also a =
considerable increase in the amount of energy that can be dissipated by the=
radiator.=C2=A0</div><div dir=3D"auto">These things together make pressuri=
ng the cooling system even to only 7 p.s.i. very advantageous.=C2=A0</div><=
div dir=3D"auto">As I mentioned earlier the problem with the 100 insofar as=
cooling system pressure is concerned is the carbon seal in the water pump =
and perhaps the design of the radiator tanks.</div><div dir=3D"auto"><br></=
div><div dir=3D"auto">M</div><div dir=3D"auto"><br></div><div dir=3D"auto">=
<span style=3D"font-size:12.8px"><br></span></div></div><br><div class=3D"g=
mail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Thu., Feb. 24, 2022, 1=
0:42 a.m. Bob Spidell, <<a href=3D"mailto:bspidell@comcast.net"; rel=3D"n=
oreferrer noreferrer" target=3D"_blank">bspidell@comcast.net</a>> wrote:=
<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord=
er-left:1px #ccc solid;padding-left:1ex">I was about to jump in and say &qu=
ot;But, but, but .... pressure only raises <br>
the boiling point but, for once, I did some 'research' first:'<=
br>
<br>
"Pressure in a cooling system is vital for keeping water in contact wi=
th <br>
the metal surfaces of the cylinder heads and block."<br>
<br>
<a href=3D"https://www.motortrend.com/how-to/understanding-the-cooling-syst=
em-cool-under-pressure/" rel=3D"noreferrer noreferrer noreferrer noreferrer=
" target=3D"_blank">https://www.motortrend.com/how-to/understanding-the-coo=
ling-system-cool-under-pressure/</a><br>
<br>
<br>
On 2/24/2022 7:01 AM, john harper via Healeys wrote:<br>
> Alan<br>
><br>
> Many A90 Atlantics suffered overheating. The club developed a fairly <=
br>
> simple adapter that screwed in place using the thread=C2=A0of the norm=
al <br>
> cap on the outside to which a shape of a 7 psi AH100 pressurized=C2=A0=
cap <br>
> fitting was added. It improved the engine cooling in many of the cars =
<br>
> that were prone to boiling over.<br>
><br>
> Best regards<br>
><br>
<br>
_______________________________________________<br>
rer noreferrer noreferrer noreferrer" target=3D"_blank">http://www.team.net=
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</blockquote></div></div>
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