Ur20v

Did anyone see the Wheeler Dealers episode on the TR6 last night?

They used Evans Waterless coolant and the main interesting fact I picked up was the system doesn't build any pressure, i.e at full running temp you can take the 'radiator' cap off and nothing happens, no steam, no boil over!?

See here: http://www.evanscoolants.co.uk/

Thought this might save us GT3 guys from blowing hoses...

Anyone used this stuff? I am going to research some more (I see the internet is a live with similar posts )

Cheers
Jay

Erik

looks very promising. not available in the US it looks like.

Fritz Flynn

Guys in the rx7 world have been using it for years in their rotary engines but I'm not a fan. The car runs hotter so you make less power etc.....

MirageJHU

Haha I was just about to post this statement exactly

Erik

^^^ hotter temperatures i.e. less power is no good. We are already robbed of HP in FL. No free lunch I guess, that's too bad

Alan C.

If the water exiting the engine is hotter wouldn't that indicate that the coolant was doing a better job extracting heat?

dasams

No, it means the engine is hotter. dave

Alan C.

In a stock system the water/antifreeze interring the engine is cooler by some delta than the water/antifreeze exiting the engine. The only way the liquid cools the engine is by heat transfer. If the coolant has a higher boiling point and creates less of a chance for local hotspots via a vapor barrier I would think it would transfer more heat. Of course you radiators would have to get rid of the heat.

Jamie_GT3

Borrowed from a GT40 forum, I was about to look up the specific heats for Evans and go through the calculations, but this guy did it for me!

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.


Evans was created for diesel trucks that can have higher operating temps and operate more efficiently at the higher temps...

dasams

All liquids have vapor pressure which always rises with temperature. When the vapor pressure reaches 1 atm at sea level, the liquid will boil. For water, that happens at 212F and for the Evans coolant, that happens at 356F per their website. So, yeah, you can remove the cap without boil over but that won't help because the pressure in the coolant system is dictated by the discharge pressure of the water pump and that doesn't change. dave

dasams

Heat capacity is a measure of the amount of heat required to raise the temperature of a substance a fixed amount. For reference, 1 BTU is enough heat to raise one pound of water by 1 deg F. Hence, the heat capacity is 1 (referred to as Cp above). If a liquid had a Cp of 0.5, that same BTU would raise it's temperature by 2 deg F.

As noted above, the Evans coolant has a relatively low heat capacity. Consequently, as each pound flows through the engine, it is heated to a higher temperature than a high heat capacity liquid, all else being equal. As a result, the engine, which generates a fixed amount of BTU's per hour, will reach a higher temperature before it reaches equilibrium. This occurs because the rate of heat transfer is proportional to the temperature difference. And since the coolant is hotter, so must be the engine. Dave

Alan C.

Thanks for the clarification.

Ur20v

Dave,

I agree with most of what you are saying apart from this; Yes the pump exerts a small pressure but as this is a closed loop system its only the friction from the water paths and the thermostat cause. The main gain in pressure is from the heated liquid which in the case of water wants to turn to steam (very poor cooler), this is the larger pressure in the system... try squeezing the coolant hoses when the engine is first started (cold) and then at running temp and you will see the massive delta.

Even in a pressurised 50/50 water cooling system there will be localised boiling which may (?) cause more problems than a small increase in overall water temp.

The difference in running temp is what I want more detail on, I haven't found any talk of 100+ deg C increases before, most talk of a very small percentage temp increase. A 100%+ increase in temp would be terminal for most engines so I find it hard to believe. I will ask Evans to provided date and references from the various race teams using this coolant.

Diesels do run hotter but have a smaller safe range that's why a burst hose (lack of cooling) on a diesel is nearly always terminal compared to a petrol which stands a good chance to escape unscathed!

Interesting discussion...

Jay

Ur20v

I don't disagree that water has an excellent heat transfer property and Evans coolant will be worse but there may not be a running temp increase if the cooling system has enough in built capacity. Flow and therefore temp is regulated by the thermostat constantly and this still works as was so its down to this built in reserves in the radiators, and our cars are built to run hard in 55+ deg C with the AC on full.

Jay

ncgt3

Evans is commonly used in racing in the US. I've used it when racing dirt bikes and karts. Cannot be mixed with water. Can purchase it directly from mfg or in various race oriented shops in the Charlotte, NC area as well as other race shops in USA.

Not cheap, but works extremely well.

http://www.evanscooling.com/