'60 overheat solved, thx NCRS

[Duke W.]

Re: ADDENDUM

Like I said, it's a "crutch" used to "solve" a hot running problem - reduce
the antifreeze or even run straight water. Does it work? Rarely. Ultimately one has to find the real problem and return the system to its original design performance.

Duke

[Duke W.]

Re: ADDENDUM

Like I said, it's a "crutch" used to "solve" a hot running problem - reduce
the antifreeze or even run straight water. Does it work? Rarely. Ultimately one has to find the real problem and return the system to its original design performance.

Duke

[Michael W.]

Thanks, makes sense *NM*

[Michael W.]

Thanks, makes sense *NM*

[don whitehead]

Re: Understand 6 Confused about 2

Thats what I thought. Hi perf motor has a 15lb cap, which I learned the hard way.

[don whitehead]

Re: Understand 6 Confused about 2

Thats what I thought. Hi perf motor has a 15lb cap, which I learned the hard way.

[Joe C.]

Re: ADDENDUM

Mike:

In the first post of this thread Don said that his car's "overheating problem " was solved. Overheating goes beyond "running hot", and implies boilover. If 2 engines both were at 260 degrees, with 15# caps, and one had plain water as coolant, the other had a 70:30 mix, then even though they were both at 270 degrees, the one with plain water would overheat (boil over) and the other would not.
The issue of heat transfer rate is not, I believe, very dependent on the coolant, but on its temperature and flowrate. It is also very dependent on the ambient temp., the efficiency of the radiator, and the flowrate of the coolant air across the fins of the heat exchanger (radiator).
The issue of temperature rise versus heat absorption is a function of the "specific heat" of the coolant. I know that pure water has a value of one (1). If the mixed coolant has a value higher than one, then it would have to absorb more engine heat for a given rise in temp. BY THE SAME TOKEN, it would have to give up more heat for a given drop in temperature.

Joe

[Joe C.]

Re: ADDENDUM

Mike:

In the first post of this thread Don said that his car's "overheating problem " was solved. Overheating goes beyond "running hot", and implies boilover. If 2 engines both were at 260 degrees, with 15# caps, and one had plain water as coolant, the other had a 70:30 mix, then even though they were both at 270 degrees, the one with plain water would overheat (boil over) and the other would not.
The issue of heat transfer rate is not, I believe, very dependent on the coolant, but on its temperature and flowrate. It is also very dependent on the ambient temp., the efficiency of the radiator, and the flowrate of the coolant air across the fins of the heat exchanger (radiator).
The issue of temperature rise versus heat absorption is a function of the "specific heat" of the coolant. I know that pure water has a value of one (1). If the mixed coolant has a value higher than one, then it would have to absorb more engine heat for a given rise in temp. BY THE SAME TOKEN, it would have to give up more heat for a given drop in temperature.

Joe

[Michael W.]

Joe, agree with you

if indeed the engine was running hotter than the boiling point of the coolant mix originally used,and as modified by the system pressure controlled by the original cap. An engine in this condition would lose coolant from boilover.

If the term 'overheat' was used in the more general sense of 'running hotter than I think it should be' and does not actually result in boilover, then Dukes' example of marginal improvement applies no matter how esoteric the actual improvement may be.

I made the assumption in my request for clarification that the car did not actually boilover,

[Michael W.]

Joe, agree with you

if indeed the engine was running hotter than the boiling point of the coolant mix originally used,and as modified by the system pressure controlled by the original cap. An engine in this condition would lose coolant from boilover.

If the term 'overheat' was used in the more general sense of 'running hotter than I think it should be' and does not actually result in boilover, then Dukes' example of marginal improvement applies no matter how esoteric the actual improvement may be.

I made the assumption in my request for clarification that the car did not actually boilover,

[Doug Flaten]

Re: ADDENDUM HEAT TRANSFER

You are correct in that the specific heat of water is 1.0. However, the specific heat of a glycol mixture is less than 1.0 meaning it cannot hold as much heat as pure water can. You also stated that the issue of the heat transfer rate is dependent on the temperature and circulation rate. But it is also very much dependent on the specific heat. At 220 degrees, a 100% concentration of ethylene glycol has over 30% less specific heat than 100% water. With increasing concentrations of glycol, in order for the same amount of heat to be rejected, the circulation rate and the amount of coolant would have to be increased in order to compensate for the reduced heat capacity. This translates into more weight, higer viscosities and more cooling system horsepower requirements.

The boiling point of the coolant is dependent on the vapor pressure of the mixture. At atmospheric pressure, by raising the glycol concentration from 0% to 100%, you could increase the boiling point from 212 degrees to about 390 degrees F. Increasing the glycol concentration may raise the boiling point substantially and prevent boilover, but it is also going to make the engine run somewhat hotter due to the decreased specific heat. The additional heat is goint to take its toll on the seals and hoses of the cooling system.

The correct glycol concentration and operating pressure of the cooling system is a balance between the coolant's boiling point, heat capacity, and ultimately the size and weight of the sytem and the horsepower required to operate it.

[Doug Flaten]

Re: ADDENDUM HEAT TRANSFER

You are correct in that the specific heat of water is 1.0. However, the specific heat of a glycol mixture is less than 1.0 meaning it cannot hold as much heat as pure water can. You also stated that the issue of the heat transfer rate is dependent on the temperature and circulation rate. But it is also very much dependent on the specific heat. At 220 degrees, a 100% concentration of ethylene glycol has over 30% less specific heat than 100% water. With increasing concentrations of glycol, in order for the same amount of heat to be rejected, the circulation rate and the amount of coolant would have to be increased in order to compensate for the reduced heat capacity. This translates into more weight, higer viscosities and more cooling system horsepower requirements.

The boiling point of the coolant is dependent on the vapor pressure of the mixture. At atmospheric pressure, by raising the glycol concentration from 0% to 100%, you could increase the boiling point from 212 degrees to about 390 degrees F. Increasing the glycol concentration may raise the boiling point substantially and prevent boilover, but it is also going to make the engine run somewhat hotter due to the decreased specific heat. The additional heat is goint to take its toll on the seals and hoses of the cooling system.

The correct glycol concentration and operating pressure of the cooling system is a balance between the coolant's boiling point, heat capacity, and ultimately the size and weight of the sytem and the horsepower required to operate it.