87kevroc

Since having my engine rebuilt last summer, I have been using either a 0/100 or, more recently, 30/70 mix of coolant/H20 in my L98 IROC. The car has been running dead center between the 110 and 220 degree marks on the temp gauge.

I forget what it was I read, but I realized water normally boils at 232 degrees F, and summer is coming, so I decided to increase the level of coolant in the system. I drained the radiator and filled it up with a little more than a gallon of coolant. I noticed the gauge was a little bit closer to the 220 mark after bringing it up to operating temperature. Now when I’m in stop and go traffic, the gauge will actually exceed 220. This has me convinced that water by itself does a better job of cooling the engine. I use a stock 195 degree thermostat.

What coolant/H20 mix do you run in your car and what temp does it normally run in the summertime? Thanks.

Z's r Best

My dad told me years ago that his trucks ran cooler in the summer with straight water in the radiators. I think it has something to do with water being a better heat transfer agent than ethylene glycol. I use 50/50 water/anti-freeze in my 86 IROC and it runs closer to 220 in hot weather than the middle mark between 100 and 220. Part of the problem is also in the design of the cooling system. My 81 Z never gets more than 5 degrees over the middle mark even in the summer while my son's 83 Z and my 86 IROC both run 20 to 30 degrees warmer during the hotter months.

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Z's r Best

dtpmike

Ive run all water before. My car runs ultra cool. I have a 160 t-stat, performance water pump(or autozone says), 3 core radiator(autozone) and it never goes past the line between 100 and 220. When I have my AC on the fan kicks in and even in trafic I dont touch that line.

I think right now I have mostly water, but then I added a little coolant to raise the boiling temperature and to keep everyhting from rusting.

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89 camaro 305 tbi, flomaster 3 chamber cat back, gutted cat, Edlebrock TES Headers, Exhaust cutout, Edlebrock open element, and a 160 degree T-stat. 2 kicker comp 12"'s, polk for the rest. Phoenix gold xs2300 to subs, kicker impulse 404XI to 4 speakers, pioneer DEH- P7000R head unit, and finally a 12 disc changer. Full leather interior from http://www.MrMikes.com (its nice)

I ROCK

Look at the stewart components web site - they have best cooling results with straight (distilled) water. The reason straight water won't boil at 232 is because of the pressure in the system. The system is under 10-15 lbs of pressure and that raised the boiling point much higher than 232. I believe Nascar engines use straight water at 25 lbs of pressure! While antifreeze in there will raise the effective boiling point even more, it's primary purpose is to lower the freezing point and you should have no problems almost anywhere in summer with straight water.

Red Devil

I thought it boiled at 212ºF. What the heck do I know?

As for the question, The pressure raises the boiling point and you want to run more water than coolant in the hot days of summer. Coolant you want b/c of the lube properties. I typically run 60/40 water on the street cars. I usually run just under 200º.

EDIT: What the hell is boild anyway?!?

[This message has been edited by Red Devil (edited May 14, 2001).]

cfabe

Water is a better heat transfer medium than ethelene glycol.

The antifreeze is mixed with water both to raise the boiling point and lower the freezing point. The pure water systems keep the water from boiling by pressurizing it like people have said. In a closed system, you can heat water as much as you want and the pressure in the system will equal water's vapor pressure at that temperature, and no boiling will occur. I dont have the numbers handy, buy you would have to significantly pressureize a system to get the water up to 240ish degrees without boiling. In a production vehicle you cant count on the cooling system being able to hold that much pressure over the years, so the antifreeze is used to help lower the pressures and keep the water from boiling. The not freezing thing is an added bonus too. Can you imagine having freeze plugs blow out every time it got colder then 32?

Vader

...and I thought it boiled at 373°K, or 672°R... but I don't know nuffin' neither....


Incidentally, the heavier molecules in glycol-based coolants tend to resist heat gain in the engine because it takes more energy to trasfer an equal amount of energy to the molecules. This means less heat energy is absorbed by the glycol than would be with plain water.

On the other end of the cooling system, once the heavier glycol molecules have accepted heat energy from the source, they tend to retain it more than reject it to the metals in the radiator. This means that the coolant returning from the radiator has been cooled less as well. You get double-whammied and all hot under the collar, not to mention the radiator cap (O.K., so I mentioned it).

It is important to have the corrosion resistance and lubrication properties of the glycol. However, for effective heat transfer water is needed to actually carry the heat energy from the engine and reject it at the radiator.

This is yet another reason to use DexCool solution, since the heat transfer ability of the product is improved over that of "regular" antifreeze/coolants. On the down-side, its smaller molecules also tend to find the smallest openings in the system and wick through or leak out, so you need a really tight system to be able to use it.

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Later,
Vader
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"Fear is how I fall, Confusing what is real..."
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Vader

...on top of that, water also boils at 71°F, but only in a 29" Hg vacuum. That IS tech, but quite off the topic, so look out for the locks.... :-)

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Later,
Vader
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"Fear is how I fall, Confusing what is real..."
Adobe Acrobat Reader

R.C. Righter

Yes. Water sheds heat far more efficiently than does 'coolant'. Anti-freeze is really just to keep you from freezing. (duh) If you really wanna see a difference, run straight water and add a bottle of Redline's 'Water Wetter'. (Pep Boys usually stocks it, believe it or not) ... That stuff is the best. Kept even my pizza oven Conquest cool ...

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R.C. Righter
86 Trans Am

87kevroc

Well, just so our facts are straight, Red is correct, the boiling point of water is not 232 but 212F (at sea level) and as Vader pointed out, 373 K.

Since the cooling system is sealed and builds pressure in proportion to it's temperature, water's boiling point has no practical relevance when deciding what mixture of coolant/water to run. It's not often the temperature here in Florida drops below freezing, and even when it does it warms up during the day, so the anti-freeze properties of the mix are not much of a concern. Think I'll just keep my eye on the temp gauge for now and if it starts running over 220 regularly, go back to a 'leaner' mixture. Thanks for the input.

RB83L69

The boiling point of water (or any other liquid for that matter) is increased by pressure. The BP of a 70/30 H20/AF mixture at 1 atmosphere + 15 psi (normal cooling system pressure, i.e. 30 psi absolute, more or less) is about 250-260°.

Every material has a property known as its "specific heat". This is the amount of heat energy required to raise the temperature one degree. Water has one of the highest heat constants in the natural world, nearly twice that of AF IIRC. That means that if you take a given mass of water and put x amount of heat into it, its temp will rise by about half of what the same mass of AF will with the same amount of heat energy added to it. That's why a car will run cooler with more water and less AF. On the other hand, the presence of some antifreexe also raises the boiling point of the water, just as it decreases the freezing point, so running pure water in a street car isn't necessarily the wisest thing to do.

IMHO somewhere around 70/30 or 75/25 is about an optimum compromise.

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"So many Mustangs, so little time..."
ICON Motorsports

Ed Maher

Funny, i just posted pretty much the same stuff yesterday in a thread on the APR board about redline water wetter. I tend to run the mixes RB suggests, 1/4-1/3 AF, no more. As i said in that post, i have fixed more than one car with temp control problems simply by draining some coolant and adding in water to dillute it. The rest of my cooling problems have generally been caused by faulty rad. caps, which is why it is now the first thing i replace on any vehicle i get now as cheap insurance.
...ed

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Ed Maher - Moderator @ The Carb Board
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Bort62

yes ed! The Radiator Cap!

It is Not Uncommon For Your Car to run up above 212F, and If your radiator cap is Not holding pressure in the system, It will boil over, where as it would otherwise be fine.

I know so Many people who have Overheating problems, and Replace everything BUT the cap, To only replace it later and solve all their problems.

AS Summer approaches, and the board fills up with overheating Questions, Keep this in mind! Its the Simple Things!.



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Ed Maher

Exactly bort...look at the boards now, heat questions everywhere, lol.isn't there a tech article on this, lemme check, if not i know what i'm doing tonight...

edit, there is a tech article but it overlooked this detail about strong coolant mixes. For a normal street car this shouldn't be an issue, but a strong running V8 really appreciates the extra cooling of a thin AF mix...have to get dirk to edit that article

[This message has been edited by Ed Maher (edited May 15, 2001).]

rezinn

Water boils at 100 degrees celcius, which is roughly 212 fahrenheit. Water has a higher specific heat capacity that any other substance, which is why it can absorb more heat than coolant possibly could. Water would be perfect for cooling automobiles if it didn't have such a low boiling and high freezing point.

Vader, degees Kelvin? :P