[DeTomaso] Radiator Caps

[michael@michaelshortt.com]

Stephen

In Panteraland, there are very few stock engines.
To the degree that the smallest changes ( Intake, carb, ignition) change
the requirements, I do not know.

There are others (like mine) that are overbuilt for their purpose, I'm sure
that I will be going with 22 over 16
for that reason.

But I'm learning a bunch about this.  ;-)

Michael


On Wed, Sep 18, 2013 at 11:52 AM, michael at michaelshortt.com <
michaelsavga at gmail.com> wrote:

> From Super Street Magazine
>
> Michael
>
>
> It’s Friday afternoon.and you and your jobless friends are bored. Such
> mindless activity arouses the proposal of a road trip and, three pairs of
> eyes fixate on you for silent nomination as the driver. After all, you’ve
> spent the past year squeezing your parents’ credit cards for those mods to
> your Integra. The turbocharged B18 and an engine-management system were
> completely justifiable expenses in your quest to be the toast of the
> show-car scene.
>
> Two hours later, the tiny coupe crawls along a clogged freeway, enjoying
> the inti-macy of Friday-night traffic. As the car<http://www.superstreetonline.com/techarticles/61718_cooling_systems/#> inches
> up a congested interchange ramp, the engine begins to run a little
> rough—then a thin plume of steam rises from under the corner of the hood.
> No one noticed the temperature needle peg itself deep into the “doom” zone.
> Nice work, sport—this completely unnecessary trip may have just cost you
> your motor.
>
> The modified engine under your faux–carbon-fiber hood is an air pump that
> uses a spark to release the potential energy of gasoline. At peak
> efficiency<http://www.superstreetonline.com/techarticles/61718_cooling_systems/#>,
> only about 30 percent of your fuel’s energy is used to create reciprocating
> power. The remaining 70 percent of the fuel’s potential energy escapes
> through the tailpipe or is converted into heat that’s absorbed by the
> cooling system. This absorption of heat is vital to proper engine
> performance. Yet important as they are, cooling systems have a tendency to
> get overlooked. Sure, they rate low on the scale of sexiness, especially
> when compared to the likes of turbocharging but remember: Engines tweaked
> to rev higher or handle forced induction to create more power also create
> additional heat as a byproduct. In these instances, a stock cooling system
> may not be able to handle the extra load.
>
> Knowledge, in this instance, is your best defense. Understanding how the
> cooling system works, how to improve it, and how to identify possible
> problems can save you from making potentially wallet-devastating mistakes
> as well as help you to maximize performance. So learn well, grasshopper,
> and don’t forget to flush.
>
> *Coolant and Pressure*
> If an engine ran without coolant, even for a brief period, the
> temperatures could soar high enough to melt a piston and fuse it to the
> cylinder wall. Metal surface temperatures in the cylinder head and
> combustion chamber can rise higher than 500 degrees F, so the cooling of
> these surfaces becomes a vital engine-design element for power and
> longevity.
>
> Honda blocks use aluminum, open-deck construction with iron sleeve inserts
> as friction surfaces. Most of the areas inside the cylinder head that are
> not of structural significance are filled with a coolant passage. The
> coolant—in most cases a mixture of antifreeze (ethylene glycol) and
> water—absorbs heat from such hot spots as combustion chambers and the
> backside of cylinder walls. While water absorbs heat effectively, it also
> freezes at a high temperature (32 degrees F) and boils at too low a
> temperature (212 degrees F) for use in cars<http://www.superstreetonline.com/techarticles/61718_cooling_systems/#> in
> certain climates. Mixing water with antifreeze yields a solution that
> benefits from a lower freezing point of -35 degrees F (for a 50/50 mixture
> of water to antifreeze) and a higher boiling point. It also adds
> anticorrosion properties.
>
> The effectiveness of the coolant—its ability to resist boiling and
> transfer heat—can be helped with Redline’s Water Wetter, which reduces the
> surface tension of the coolant. Another option would be Evans’ NPG coolant,
> which is designed for use without water, allowing you to run a
> zero-pressure cooling system. At zero pressure, this waterless coolant has
> a boiling point of 360 degrees F.
>
> A major component of coolant-system maintenance is the periodic flushing
> of the system. Old antifreeze/water mixtures can actually become corrosive
> to metals after extended use, but they must be disposed of responsibly, as
> the mixture is toxic. Sealing the radiator’s filler neck on modern cooling
> systems is a rubber-gasketed cap with a spring-loaded valve that
> pressurizes the system and increases the coolant’s boiling point. Factory
> radiator caps typically increase the cooling-system pressure by 14 or 15
> psi and raise the boiling point about 43 degrees F. As the engine warms up,
> the coolant heats up and expands, causing pressure to build up; the cap’s
> valve is the only place where this pressure can escape. When the system
> pressure reaches the cap’s pressure rating, the cap’s spring is compressed,
> forcing the valve open and allowing coolant to escape through the overflow
> tube to the expansion tank. This also permits air to escape the cooling
> system; as the radiator cools down, the vacuum created by the cooling
> system contracting pulls down another spring- loaded valve, returning
> coolant to the radiator. Due to the pressure contained by the radiator cap,
> and the fact that boiling liquid can lead to Darkman-like disfiguring
> burns, it’s never a good idea to open a radiator cap while the engine is
> still hot—and certainly never when you’re in the nude.
>
> *The Pump and the Thermostat*
> Coolant must flow through the block and head in such a way that it can
> absorb and transport heat without boiling. When coolant boils, its
> capability to absorb heat is diminished, causing temperatures to rise
> dramatically.
>
> Coolant makes its way from the bottom of the block and out of the cylinder
> head to the radiator by a mechanically driven centrifugal pump. The water
> pump also draws coolant from the radiator and forces it through the engine
> at a higher pressure.
>
> A thermostat regulates the flow of coolant from the block to the radiator.
> By varying the size of its aperture, the thermostat slows coolant flow to
> ensure that the coolant will spend enough time in the block and cylinder
> head to absorb heat. On a cold engine, the thermostat completely restricts
> flow to the radiator block outlet. The thermostat uses a wax-filled
> cylinder to open at the prescribed temperature. A rod connected to the
> spring-loaded valve in the cylinder presses against the wax. As the wax
> heats up, melts, and expands, the rod is pushed out of the cylinder and
> opens the valve. The thermostat is located at the top of the engine at the
> coolant outlet, where coolant temperatures are highest.
>
> Typically, a car runs most efficiently when the coolant temperature is
> kept around 200 degrees F. At this temperature, the combustion chamber is
> warm enough to vaporize the fuel mixture for improved combustion, and the
> oil’s viscosity has lowered sufficiently to reduce parasitic drag.
>
> *The Radiator: Heat Transfer and Airflow*
> The modern radiator is constructed of densely finned, aluminum cores
> usually with plastic tanks. Aluminum has a very efficient<http://www.superstreetonline.com/techarticles/61718_cooling_systems/#> rate
> of heat transfer and the structural strength to withstand higher system
> pressures.
>
> From the factory, most radiators are designed to match the heat output of
> a stock motor. The radiator sits behind the grille opening in the path of
> air that rushes in when the vehicle is in motion. When super-heated coolant
> is pumped from the top of the engine into the radiator, it flows through a
> structure of tubes. Folded aluminum fins connect the tubes, and the metal
> absorbs the heat of the coolant. Air entering through the grille moves
> across the tubes and fins, and cools them by transferring the heat to the
> ambient air.
>
> The fins-per-inch measurement gives an indication as to how effectively
> the unit will transfer heat. More fins of folded metal result in greater
> surface area for air to flow over and increased heat transfer. After-
> market aluminum radiators, such as those offered by Fluidyne, not only have
> a high density of fins, but they also have wider aluminum cores to provide
> greater cooling surface area and coolant capacity.
>
> The rugged, all-metal, welded or epoxied construction of such radiators
> can also handle higher coolant-system pressure, and it maximizes the
> temperature differential between the coolant entering the engine and the
> super-heated fluid entering the radiator. A high-pressure radiator cap
> (such as a 24-psi unit) is available from many aftermarket-radiator
> suppliers, but such pressure puts greater stress on the rest of the system
> (clamps, hoses, gasket surfaces, and so on). When a vehicle is at rest, or
> moving slowly, the airflow must be maintained through the radiator so it
> can continue dissipating heat. A fan provides constant airflow through the
> radiator; the fan is electric in most front-wheel-drive cars, since the
> engine’s power output is oriented toward the side of the car.
> Thermostatically controlled pusher or puller electric fans (aka “blow” or
> “suck” fans) draw air through the radiator core once the coolant reaches a
> predetermined temperature.
>
> *Lost Coolant*
> One of the most common causes of overheating is a low coolant level, which
> reduces the system pressure and the coolant boiling point. Pressurized
> systems with full coolant levels and functional expansion tanks are more
> effective at maintaining temperatures.
>
> Cracked hoses, faulty hose clamps, bad thermostat housing gaskets,
> radiator pinhole leaks, leaky expansion tanks, and tired radiator caps are
> common culprits of pressure loss. Leaks can often make slight hissing
> sounds and can be identified visually after the car has been running. If a
> head gasket is compromised, however, coolant can escape through a
> combustion chamber, mixing oil with the coolant. Traces of exhaust gas and
> oil can be seen floating in the coolant, and this means that the top of the
> engine must be removed and resurfaced to replace the gasket.
>
> Casting imperfections, such as hairline cracks or weeping freeze plugs,
> relieve system pressure just as easily as pinhole cracks in the radiator
> do. Temporary solutions for leaks include JB Weld (a “stronger than steel”
> epoxy welding agent) applied to the crack or fissure, or such radiator
> sealing agents as Alumnaseal or Bars Leak. These agents use a ceramic or
> metallic medium that mixes with coolant or water to help seal leaks. Most
> sealing agents are only temporary repairs at best, and ultimately, parts
> will need to be replaced or welded.
>
> While some radiators can be repaired, most shops will just replace the
> whole unit. This plastic-tank/aluminum-core construction has proven to be
> the weakness of the Honda radiator. A radiator passage can become clogged
> with debris, reducing coolant flow through the core and fins and reducing
> heat transfer. While debris can be removed with rods that clear the
> radiator core, most shops will just opt to replace the radiator.
>
> *How It Can All Go So Wrong*
> If a cooling system maintains the correct pressure and fluid level, and
> yet the engine still runs hot, then the problem has more to do with the
> fluid flow rate or airflow/heat exchange rate. Coolant flow is managed by
> the churning of the water pump and the variable restriction provided by the
> thermostat, and the operation of these two components can be altered to
> suit the engine’s cooling needs. Typically, water-pump failure is
> accompanied by the squealing noise of cashed-out impeller-shaft bearings,
> or the pump just leaks at the seals.
>
> Water-pump impellers are designed to be most efficient<http://www.superstreetonline.com/techarticles/61718_cooling_systems/#> at
> pushing water through the cooling system at the lower speeds at which
> street engines tend to live. At very high rpm, however, temperatures can
> rise because some water pumps pump more air than coolant. In such
> instances, many racers increase water-pump pulley size to reduce the
> water-pump impeller speed at higher rpm, therefore getting more effective
> cooling during races.
>
> A slipping belt is also an overlooked cause of high-rpm overheating. It
> results in a pump impeller that spins more slowly relative to crankshaft
> speed and thus can’t move coolant quickly enough.
>
> *Thermostats*
> If overheating persists after the operation of the thermostat has been
> tested (using a pot of boiling water and a thermometer), consider that
> switching to a lower-temperature thermostat will allow more coolant into
> the engine sooner.
>
> Thermostats that open sooner can help increase coolant flow, but the
> coolant spends less time in the engine absorbing heat. Switching to a
> lower-temperature thermostat is just a Band-Aid remedy, however; it’s also
> necessary to increase the pressure of the cooling system with a stronger
> radiator cap.
>
> With an adequately pressurized system and an efficient radiator, a
> higher-temperature thermostat (190 degree F instead of 180) will improve
> engine cooling—it will slow the coolant and do a more thorough job of
> absorbing heat. The larger temperature differential between the ambient air
> and coolant temperature will need peak radiator efficiency to control
> temperatures.
>
> *Better, Stronger, Faster*
> Unless you’re a sorcerer, not a whole lot can be done to control the
> temperature of ambient air. You can, however, control the temperature
> differential between the coolant and incoming ambient air. Ideally, you
> want the coolant to absorb as much heat as possible before it turns into
> vapor pockets, and then send the heat to the radiator for the most dramatic
> temperature reduction possible. Typically, a 100-degree differential is the
> desired target.
>
> Quite a bit can be done to improve the flow of air through the radiator,
> thus maximizing its heat-exchanging capabilities. The electric fans that
> provide airflow for most front-wheel-drive cars are designed to draw air
> through the radiator of a motor with a near-stock power level. The heat
> generated by higher horsepower requires more aggressive airflow.
> Aftermarket companies, such as Flex-a-Lite and SPAL, offer a range of
> electrical fans that can move larger quantities of air than OE cooling
> fans; these fans also provide different mounting possibilities. Whether it
> be pusher or puller fans, such devices are crucial to help maintain airflow
> when the vehicle is in traffic or just moving slowly.
>
> A fan shroud fitted around the perimeter of the radiator also helps direct
> airflow through the aluminum heat exchanger instead of around it. Radiator
> airflow can also be improved on a moving vehicle by an air dam mounted
> under the car’s front bumper, which forces air that would otherwise go
> under the car up into the grille opening and through the radiator.
>
> The majority of enthusiasts spend so much time combing ads for the next
> great power-adding device or scheming of ways to make the larger engine
> swap fit, that they never consider the extra heat that these modifications
> will generate. Addressing a performance engine’s cooling needs as part of a
> buildup will save you time and headaches on your dream car project.
>
>
> Read more:
> http://www.superstreetonline.com/techarticles/61718_cooling_systems/#ixzz2fGBK6AJJ
>
>
> On Wed, Sep 18, 2013 at 11:33 AM, michael at michaelshortt.com <
> michaelsavga at gmail.com> wrote:
>
>>
>>
>> Just found this at Stewart gauges website.
>>
>> Michael
>>
>> *Tech Tip #2 - Radiator Caps
>>
>> Radiator Caps*
>> In a cooling system, a higher pressure equates to a higher boiling point
>> for the coolant. Higher coolant pressures also transfer heat from the
>> cylinder heads more efficiently. We recommend using a radiator cap with the
>> highest pressure rating that the radiator is designed to accept. In
>> general, performance radiators will accept 22-24 PSI, and professional
>> racing radiators will accept a 29-31 PSI.
>>
>> The coolant will typically only build to 16-18 PSI, due to expansion up
>> to 200°F. However, if the engine does overheat due to external factors, the
>> pressure inside the cooling system could reach as high as 28 PSI. Once the
>> radiator cap has opened and vented coolant, the engine will not cool down
>> until it has been turned off. The radiator cap is basically a "safety
>> valve", so always use the highest pressure radiator cap that the radiator
>> will tolerate. If you are unsure of the pressure rating for your radiator,
>> check with the manufacturer for the maximum recommended operating pressure.
>>
>>
>> *Radiator Cap Location
>> *The radiator cap should always be located at the highest point of the
>> cooling system, and on the low pressure side (after the radiator
>> core).Cross flow radiators mounted higher than the engine are ideal because
>> the cap is on the tank that is connected to the water pump inlet. This
>> configuration offers 3 advantages:
>>
>>   1.The cap is at the highest point of the system, allowing any air to
>> migrate to the area just below the cap. In the event the cap vents due to
>> excessive pressure, the air will escape first. 2. This area has the
>> lowest velocity within the system, allowing air to separate from coolant
>> even at high engine RPM. 3. The cap is located on the low pressure
>> (suction) side of the system, so it is unaffected by the pressure generated
>> by the water pump.
>> For cooling systems NOT using a cross flow radiator, mounted higher than
>> the engine, you must use a surge tank. A surge tank is typically a 1 quart
>> tank mounted at the highest point of the system, with the radiator cap on
>> top. The bottom of the tank is connected to the inlet side of the water
>> pump with a 1/2" or 3/4" line. A 1/4" to 3/8" "bleed" line from the side of
>> the surge tank is connected to the highest point of the low pressure side
>> of the radiator. The bleed line allows some circulation through the tank
>> while the engine is running. The surge tank is also large enough to allow
>> the air to separate as the coolant flows through it. Air in the system will
>> then migrate to the area just below the radiator cap, again so that it will
>> forced out first if system pressure exceeds the radiator cap's rating.
>>
>> In street car applications, an upright radiator (top and bottom tanks,
>> with the cap on the top tank) represents a compromise that will work, as
>> long as the car is not operated at sustained high RPM, like those seen in
>> racing.
>>
>> *Any aftermarket thermostat housing that mounts the radiator cap
>> directly above the thermostat location, or that mount the radiator cap in
>> the top coolant hose, are NOT recommended. Both of those housing styles are
>> poorly designed, and will push coolant out of the cap at high RPM.
>> *
>>
>>
>> On Wed, Sep 18, 2013 at 11:28 AM, michael at michaelshortt.com <
>> michaelsavga at gmail.com> wrote:
>>
>>> Every pound of pressure raises the boiling point of water 3 degrees. if
>>> your system is designed for 10 psi and the cap is capable of holding that
>>> you have increased the boiling point 30 degrees.
>>>
>>> So a 16 psi cap could stand a temp of  260 degrees, whereas 22 psi could
>>> handle up to  278 degrees.
>>>
>>> I guess none of us want temps anywhere near 260 anyway, so perhaps the
>>> lower rated cap is sufficient.
>>>
>>> The next point then becomes, if the cap fails to release the pressure,
>>> then something else might, like a hose, gasket, etc.
>>>
>>> Michael
>>>
>>>
>>> On Wed, Sep 18, 2013 at 11:20 AM, Larry Finch <fresnofinches at aol.com>wrote:
>>>
>>>> Overflow is zero pressure cap.
>>>>
>>>> But why so high - 22PSI - on the surge tank cap?
>>>>
>>>> Larry
>>>> _______________________________________________
>>>>
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>>>>
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>>>> http://poca.com/mailman/listinfo/detomaso
>>>>
>>>
>>>
>>>
>>> --
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> 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
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>> --
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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
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>
>
>
> --
>
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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
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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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privileged.  If you are not the intended recipient, you are hereby notified
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communication is strictly prohibited.  Please reply to the sender that you
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