Water less coolant

[saildrive2001]

No need to have a pressurized radiator cap, it doesn't boil until a much higher temp than water. I have just put it in my Elan but only have 350 miles on it since the rebuild. A friend has run it in a twincam 7 & now in his Europa for many years wihtout a pressure radiator cap.

[AHM]

Ok Gents, Time for some facts!

What is the purpose of coolant?
1. Primarily To keep the engine cool
2. Secondary to not freeze
3. Secondary not to boil
4. Secondary to inhibit corrosion
5. Secondary to lubricate coolant pump
6. Secondary to keep system pressure down

anymore?

We use water because it has (and this is the important bit!) a relatively good coefficient of thermal conductivity k=0.58 so it is good for cooling and is cheap and plentiful. But it is not so good at the secondary points 2,3,4,5,6. So we add "An tifreeze" which is more expensive and less good at cooling k=0.25 for ethylene glycol (others are available!)

Now, I am primarily concerned with keeping my twincam engine in its normal operating range of somewhere between 80 and 95 oC. So I want the highest k for efficient cooling, and sufficient additive to provide the secondary properties in my operating conditions. I.e. most water and least "anti-freeze" for my conditions - see the manual!

Note also that Cooling is about getting the heat out of the hot body into the Cooler body. The greater the difference in temperature between the two bodies the greater the heat transferred. We ultimately want to get heat into the air

So now let us consider Evans product which I am sure is very good under the particalar circumstances that water-antifreeze cannot handle..

As a normal road user:
I Want to keep my engine temperature below 95 oC so boiling is not a major concern - If it runs hot I have another problem.
The "antifreeze" mixture provides the secondary requirements and is good down to -17 oC at 30% and -25oC at 40% so the secondary requirements are covered

Which leaves me with the cooling properties.
I cannot find on Evans' Website a value for k. But I have found a comment in their FAQ's
Q. Will Evans Waterless Coolant cause my engine to run at a higher temperature?
A. The operating temperature of the engine and coolant may increase slightly, by approximately 3-7 degrees......Remember the above note about the difference in temperatures - This suggests that the coefficient of thermal conductivity is less than that of water/antifreeze.

The effectiveness of a cooling system is controlled by the characteristics of the radiator and thermostat - While driving; a lower k will mean that the thermostat is open wider/longer to allow more coolant through the radiator.
In traffic the fan will run longer, and if the system is marginal the engine will run hotter.

There is lots of stuff on Evans' website about other characteristics - it would take another essay to discuss that! I suggest you read their FAQ.

Personally with my cars I aim to keep below 95 oC and prefer to get more heat out quicker - I'll stick with 70/30 Water/Anti-freeze and spend the money on a decent fan.

[Galwaylotus]

Well said. I think too often people focus on a detail at the expense of the big picture.

[AHM]

No need to have a pressurized radiator cap, it doesn't boil until a much higher temp than water.

But what is the advantage in that?

How hot do you run your engine?

[Coupe]

Prior to switching to Evans my S3 (wide radiator) normally ran at no more than 70c -75 c so even a slight increase could even be beneficial. I also run an expansion tank.

[AHM]

Prior to switching to Evans my S3 (wide radiator) normally ran at no more than 70c -75 c so even a slight increase could even be beneficial. I also run an expansion tank.

I don't get your meaning - why buy a product that you don't need, for an overheating problem that you dont have? Just buy a new thermostat for four quid!

[bcmc33]

Prior to switching to Evans my S3 (wide radiator) normally ran at no more than 70c -75 c so even a slight increase could even be beneficial. I also run an expansion tank.

Running at this temperature is perfect for performance - but probably very poor for economy.

Just buy a new thermostat for four quid!

Thanks for the reminder...........the last time I ran my car was getting home from last November's Classic Car Show and the temperature gauge did not get above 35?c and the heater was blowing just as cold as the wind through my hair...........must fit a new thermostat was my conclusion.........must do something about that NOW.

[jk952]

Excellent technical points made by many.
One consideration I don't recall seeing is failure mode effect. If a water based system does overheat, for whatever reason, then with the pressure drop I believe the sys is exhasuted to useless quickly, leaving little time to get shutdown or risk engine damage. With the higher boiling point and it not maintained by pressure, it may give you some peace of mind, as it wouldn't flash out suddenly.
Jk

[Mazzini]

Just noticed that my previous post was number 787. Guess I'm grounded!!

hahah lol Good one.

[saildrive2001]

The advantage with not pressurizing the cooling system is that non of the system including the heater is not under the same stresses as a pressurized system. The fact that the system is not pressurized has no effect on the engine temp, a pressureized system only means that you can run the coolant at a higher temp than 100c before it boils away.

[AHM]

Keith,

The cooling system is designed to be under pressure - at 9 psi the boiling point of water is 112 oC (110oC @7Psi) and add about 4oC for a 70/30 coolant let?s say 115oC (I can't find a chart!). Also the pump may be more effective with some system pressure.

Once you are at 100 oC the system capability is maxed out this is where the k value is significant. Water is better able to get rid of the heat. I.e. For a coolant with a lower k to get rid of same amount of heat the engine will be hotter (see earlier note) so Evans coolant will be running at 107 oC. ..... You are looking for the exit and I'm still ok to sweat it out!

If you have conditions where you are regularly around 100oC invest the money in a better fan, then an oil cooler.

Notice I didn't say an aluminium radiator - Copper (k=400) has twice the heat transfer capability of Aluminium (K=200)

If it is cold temperature performance that concerns you a 50/50 Water /Antifreeze mixture will equal the -40oC of Evans and 60/40 will go to -50oC

[Spyder fan]

This reminds me of the old silicone brake fluid versus glycol!

More snake oil here http://www.redlineoil.com/product.aspx?pid=74&pcid=10

Water expands when heated, so does Evans water less coolant:- the following quote is from their web site.

Do I use the same volume of Evans Waterless Coolant in my cooling system as before?
Yes, Evans Waterless Coolant thermally expands to within 1% of 50/50 water based coolants at 100?C so you can use the existing fill level in your cooling system for Evans Waterless Coolant.

So much for lowering pressure. I second all the comments about opening the radiator cap when hot..... don't!

[higgyuk]

Has anybody had any experience of Evans waterless coolant which seems to be in vogue at the moment.Seems expensive

havnt used it but its used in SPITFIRES as it absorbes 17 times more heat than water ethyene glycol seem mad too me higgyuk

[Galwaylotus]

This reminds me of the old silicone brake fluid versus glycol!

More snake oil here http://www.redlineoil.com/product.aspx?pid=74&pcid=10

Water expands when heated, so does Evans water less coolant:- the following quote is from their web site.

Do I use the same volume of Evans Waterless Coolant in my cooling system as before?
Yes, Evans Waterless Coolant thermally expands to within 1% of 50/50 water based coolants at 100?C so you can use the existing fill level in your cooling system for Evans Waterless Coolant.

So much for lowering pressure. I second all the comments about opening the radiator cap when hot..... don't!

Thermal expansion is one thing and the boiling point is another. The real danger of releasing pressure on a system that's above the boiling temperature is that it then starts to boil and the hot mixture volume increases dramatically. Releasing the pressure on a liquid that is below boiling point (at atmospheric pressure) only results in the increase in volume due to the coefficient of thermal expansion. I'm speaking in generalities here as I don't know the properties of Evans coolant due to temperature or pressure changes.

[Spyder fan]

Let me get this straight.

The Evans stuff expands to within 1% of a standard water/glycol mix at 100 degrees. Are you saying that nothing will come out of the pressure cap if you open it when the engine is hot?

Maybe we need a whip round to buy some and run some tests?