Evans coolant

[Will Campbell]

Has anyone actually used this? It seems like an interesting product, since it permits higher temps before boiling, but more importantly is said to lower average temps just by more efficient temp transfer at the heads/coolant interface.

Comments?

 

[Ron Earp]

Water works well. If you have problems cooling while using water then you have problems that shouldn't be solved using Evan's coolant. Your entire engine is designed around water's operating parameters including the thermal expansion of various parts at the thermostat set point.

Also not sure what various tracks think of Evan's coolant. With antifreeze being outlawed at more than a few tracks, that is water cooling only, I suspect Evan's Coolant won't be too welcome either.

 

[Rick Muck- Mark IV]

It is discussed on ClubCobra here: Waterless Coolant? - Club Cobra

One of the supposed advantages is you run a very low or no-pressure system.

 

[Alan R]

Plus it's not corrosive and it doesn't create steam pockets. I just bought 5 gallons of the stuff not cheap

 

[JohnC]

There's a lot of misinformation and misunderstanding of heat transfer in the hotrod circles, and anyone who says/believes that Evans cools better than water has been misinformed because it's just plain wrong.

Here's the simplified heat transfer equation:

Q = 500*GPM*deltaT*Cp

Q is the amount of heat energy in BTU/Hr that we can move from the engine to the radiator.

GPM is the flow rate of the coolant from the engine to the radiator in gallons per minute.

DeltaT is the temperature differential between the top & bottom tanks

Cp is the coefficient of specific heat for the coolant being used. It's a physical characteristic of the fluid itself and is an indication of how much heat that fluid can carry.

Water has a Cp of 1.0 and all other commonly available coolants have a Cp that is some fraction of 1.0. What this means is all commonly available coolants will carry less heat away from the engine than water.

Pure (100%) Ethylene Glycol has a Cp as low as 0.55 to as high as 0.69. When mixed 50/50 with water, the EG/Water coolant then has a Cp of from 0.79 to 0.85, so all other things being equal, it will carry from 20% to 15% less heat away from an engine than pure water.

Evans coolant has a Cp as low as 0.64 to as high as 0.68, so all other things being equal, it will carry from 36% to 32% less heat from the engine than pure water.

What does all this mean?

Pure water is the best coolant available. 50/50 water & EG is the most common mix used, and works nearly as well as water. Some people who go with a 50/50 mix and a bottle or two of Water Wetter see no difference after adding the WW. Others who go with pure water and a bottle or two of WW see a nice drop in engine temperature and give WW all the credit, but based on the above relationships, It's easy to see the WW had little to do with the temperature drop and it's the pure water that has everything to do with it.

Those who run Evans will have scary high engine operating temperatures. Increases of 75-100 degrees F are not uncommon, and in fact, to partially offset its poorer heat transfer abilities, Evans recommends smaller pulleys be run on the water pumps so more coolant is pumped.

Here are Evans' positive attributes:

Will not freeze or boil over
Little or no danger of cooling system corrosion when changed over from EG correctly

The negatives:

Extremely high engine operating temperatures - this may or may not be a problem for you, but for myself, the much higher operating temperatures are enough to keep me from ever using the stuff. The engine manufacturers are familiar with an operating envelope from 180-220 degrees F and know very well how reliable the engine and its ancillaries will be within this envelope. Once that envelope is raised 75-100 degrees, we're in unknown territory.

If you feel your engine can tolerate the higher operating temperatures, give it a try, but don't do it because you've been led to believe it will cool your engine better than EG & water, or pure water. It's simply not true.

 

[Seymour Snerd]

John -- Thanks for the articulate post. Here's what I don't get, and it may just be a question of psychology. If you go to their web page, the very first thing it says is "Increasing the Operating temperature means the fan does not have to run as much, increasing fuel economy by up to 10%"

So, why is anyone in our situation (where for a variety of reasons we're normally fighting to keeps temps down) interested in this stuff? Does anyone in the high-perf. street and/or track/race community believe that higher operating temperatures are a good thing? In particular, if I have a properly functioning thermostat-controlled cooling system using water or 50% glycol, why would I consider switching?

On further thought... it seems part of their argument is that due to no boiling or cavitation local gas pockets are eliminated, and I don't know whether "no gas pockets" in a water-cooled system is a reasonable stipulation for "properly functioning".

More generally, as far as I can see the simplified heat transfer equation has no term for thermal conductivity, and at least practically speaking I would think the "gas pocket" problem falls under that; IOW regardless of the fluid's specific heat, if it can't make effective contact with surrounding metal then heat transfer is impeded. Regarding water wetter, my impressions has been that they claim better cooling via lower "surface tension" in the coolant thus providing better conductivity, independed of specific heat, and thus that even in a formerly pure water system there would be an improvement. Am I incorrectly imagining that effective thermal conductivity matters? Is the simplified heat transfer equation over-simplified?

 

[Rick Muck- Mark IV]

Evans was designed for the heavy-duty diesel truck market. And the idea of running a 15 liter diesel at higher temps is attractive to the industry. A diesel does not have a pre-ignition problem and high temps will not cause it to "diesel" on shutdown as the engine is stopped by stopping fuel from being injected, not the removal of the ignition source. When running Evans the engine temp will be higher but more consistant, the thermostats will stay open and the fan clutch will not engage as often thus saving fuel (a heavy truck fan takes a LOT of power to function!) and all of the heat energy goes to move the truck and pay;oad.

 

[JohnC]

Alan / Rick, I'm also mystified by the statements Evans have made about fan cycling, as well as other claims, and perhaps it's as Rick says for the fan cycling.

In most of our cases, however, since the fans are electric and are kicked on/off by temperature switches/sensors, it would be the inverse situation, and they'd probably never shutoff unless you changed the temperature switches (or reranged the setpoints of their controllers if they have analog outputs).

Alan you're right about the simplified equation not taking into account improved conductivity nor the use of surfactants like WW that reduce the surface tension of the coolant. The "real" heat transfer equation has factors for that, as well as efficiency (fouling) on both the coolant & air sides, plus takes into account turbulence in the fluid, etc. It's also a much harder equation for mere mortals like us to understand as it's written in partial differential format. Unless you specialise in heat transfer and thermodynamics (which I don't), the simplified equation is much easier to grasp and work with, and it's good for doing ballpark calculations.

 

[Mike]

John, are your assertions about temps running 75-100 degrees hotter based on experience or calculations and theory? I used Evans in a 750hp TT Cummins Dodge and temps were no different than when running 50/50 glycol water mixture. I understand the physics and your calculations but question your baseline. Most cooling systems do not run with wide open thermostats and in fact, even with Evans I would rarely ever turn on the electric fan in my truck on all but the hottest days in traffic. I would guess that as operating temps reach the point at which the thermostat opens, that unless you had some other limitations, most cooling systems would easily maintain optimum operating temps using Evans. Does your experience suggest otherwise?

 

[Seymour Snerd]

I used Evans in a 750hp TT Cummins Dodge and temps were no different than when running 50/50 glycol water mixture.

I think to get the effect Evans is after that Rick describes you have to also raise the thermostat set point.

 

[JohnC]

Michael, as I've not used Evans or any other propylene glycol based coolants myself, the assertions I've made are based on the math, plus the experiences others have reported, including the statements by Evans themselves.

With the diesel, you already have an engine that is running some 10-15% more efficient than a comparable spark ignited engine, so it's rejecting less heat to the coolant, and the whole cooling system doesn't have to work as hard. Then on top of that, if your cooling system was oversized for towing, you have even more reserve, so it's entirely believable that you didn't see a rise in temperatures. The inefficiency of the heat transfer fluid has only reduced the amount of reserve margin that you once had.

This isn't the case with highly tuned, spark ignited engines that have marginally sized cooling systems, such as the sports cars we're talking about here, where any loss of cooling system efficiency is going to send the temperatures up.

 

[Mike]

It definitely had plenty of cooling capacity. I guess based on my experience I was not sure about the assertion that temps would run that much hotter. Mine had a 195f thermostat in it and it ran right there no matter what whether running Evans or glycol mix. I suppose if a cooling system was 100% taxed and the thermostat was wide open allowing maximum flow, then switching to Evans would definitely raise temps. I don't know on my gt40 how open the thermostat is during normal operations. I did like the lack of corrosion using it as well as the higher boiling point which is important up here a mile high in Denver. Maybe I'll switch out this winter when the car is parked and see how it works next spring.

 

[Dave]

Just saw this thread.

I've used Evans for years with many turbo charged rotary engines under road race and street conditions. When I switched over from water/ww, I only saw about a 10-20 degree increase in temps across the board and the temps stayed more consistent under heavy loads. Never did I see my temps or hear of anyone else using the product have 100 degree temp increases but my sample pool is relatively small. My cooling system was properly designed and worked well before the switch but I did have to upgrade to a larger expansion tank. What made Evans attractive to me was that I could run it at zero pressure... a big plus for any engine, especially rotaries. Think about that.

Did Evans cool the engine better? I can not answer that but like I mentioned before, the temps would not climb as fast or easily after the switch. Evans touts their products ability to resist gas pocketing around internal hot spots in the engine which may or may not contribute to higher operating temps. If their product is any more effective than a water/ww mix under pressure, I do not know.

There are downsides to Evans though and several times I have thought of switching back to water/ww.

Cost
Availabilty
Feels like brake fluid (effing nasty)
Not allowed by some tracks/sanctioning bodies

I'm still on the fence if I will use it again with my current build.

 

[Jim Glickenhaus]

We use it in Ferrari P 4/5 by Pininfarina for several reasons. As it runs at zero psi the entire system is under less strain. (hoses) As it doesn't boil until VERY high temperatures it doesn't raise air bubbles and thus stays in contact with the surfaces it runs on cooling those surfaces much better. The lack of entrapped air also allows the water pump to run without caveating. Generally engines with Evan's run cooler because of the absence of entrapped air bubbles. Without adjusting the flow P 4/5 ran 15 degrees (F) cooler. If you want to run hotter you can as hotter produces more HP but you can run hotter without having to use a 25PSI radiator cap which puts the entire system under strain. F1 cars use Evans like fluids and there's a reason they do.

 

[Jim Cowden]

I spent an evening with a chemist who designed coolant.
One of the important issues he spoke about was around the exh ports under load air bubbles come off the surface of the casting due to heat.
Like the element in your jug when it is starting to heat up, he claimed that everytime the bubble form and leaves the surface it is like a small explosion and slowly erodes the casting,hense pin holes in ports.
The coolant allows the heat in the port to transfer of the surface and be distributed into the cooling system more evenly without the bubbles forming.

I would sell about 2000lt of coolant (glycol) per year and I have to admit I never pull heads off engines for these issues.

I do agree with Ron ,if you have a problem coolants wont fix it.


Jim

 

[Jim Rosenthal]

We use it in Ferrari P 4/5 by Pininfarina for several reasons. As it runs at zero psi the entire system is under less strain. (hoses) As it doesn't boil until VERY high temperatures it doesn't raise air bubbles and thus stays in contact with the surfaces it runs on cooling those surfaces much better. The lack of entrapped air also allows the water pump to run without caveating. Generally engines with Evan's run cooler because of the absence of entrapped air bubbles. Without adjusting the flow P 4/5 ran 15 degrees (F) cooler. If you want to run hotter you can as hotter produces more HP but you can run hotter without having to use a 25PSI radiator cap which puts the entire system under strain. F1 cars use Evans like fluids and there's a reason they do.

Jim, did you use a hotter thermostat and if so, what rating?

 

[Jim Glickenhaus]

Jim, did you use a hotter thermostat and if so, what rating?

We didn't as when we drove her on the Bahrain F1 track for many laps as her radiators filled up with sand she got warm enough. Basically we like Evans because it doesn't start to bubble and remains in contact with the metal. You really don't want to overheat one of these engines but we've run her right up to the red line without issue.