Evans High Performance Waterless Coolant Evaluation

nsxspdfreak · 7 August 2017

Evans Waterless Coolant Evaluation – 1991 NSX Normally Aspirated.

A friend of mine had put me onto Evans Waterless Coolant and its benefits of 0 corrosive properties, less stress on cooling system components due to the fact that it can operate at atmospheric pressure due to its 375deg boiling point, and its ability to not degrade/breakdown over time and therefore last the life of the car. Since it was time to replace all the coolant hoses in my 91 NSX I decided it was a perfect time to give Evans High Performance Waterless Coolant a shot.

One of the problems with water-based coolants is its low boiling point temperature. Boiling coolant has poor heat transfer capabilities so the cooling system is designed to operate under pressure in order for the coolant to operate at a high temperature without boiling. The point at which coolant boils is determined by the coolant to water ratio and the pressure rating of the radiator cap. A normal 50/50 mix with a 15lb cap will boil at 265deg. Increase the coolant to water ratio to 60/40 and the boiling point increases; however, running higher mixes of coolant to water can result in a loss of heat transfer capability due to increased viscosity. 100% water provides the best cooling properties, but it’s corrosive and has a lower boiling point (257deg @ 15psi). Running with pure water with a standard 16lb cap could result in the water boiling in areas of the motor especially around the exhaust valves, which could lead to damage to the valves and large differential temperatures within the motor. Metal temperatures near the exhaust valves reach and can exceed boiling points of the coolant, but boiling along the metal surfaces can be beneficial to cooling as long as it remains in the nucleate boiling state and there is circulation. This is how nuclear reactor cores are cooled and why the bottom a boiling pot of water doesn’t melt (I’m very familiar with nucleate boiling due to my 10 years as a Senior Commercial Reactor Operator). When the surface temps reach a high enough temperature the ability of the circulation system and the coolant to remove the heat is exceeded and the state of boiling changes from nucleate to film boiling. At this point heat transfer rates drop dramatically as a vapor barrier forms between the metal surface and the coolant. Within the head there can be areas where temperatures and poor circulation will result in the phase change from nucleate to film boiling. When this happens there are some drastic temperature differentials that may be experienced along the metal surfaces. When the motor is shut down circulation ceases and metal temperatures continue to rise, which will result in film boiling causing excessive and uneven metal temperatures.

Cavitation from the formation of vapor pockets is other factor that can cause problems with wear and decreased cooling efficiency. The inlet of the water pump operates at a lower pressure than the outlet which results in a lower boiling point for the coolant entering the pump. If coolant temperatures are high enough boiling can occur within the pump resulting in cavitation. Cavitation will cause erosion and reduce the pump’s efficiency. This same low pressure condition can occur as coolant enters small channels or goes through sharp turns.

The point is that any boiling other than nucleate boiling is not good. Being that Evans coolant boils at 375deg, contact between metal and the coolant isn't lost due to the formation of boiling coolant vapor barriers except possibly under extreme conditions; therefore, metal temperatures stay more uniform throughout the motor during operation and after shutdown. Cooling system temperature gauges only provide a broad overview of how the cooling system is performing, but are a poor indication of what’s going on in different areas of the motor.
Evans does have a higher viscosity than water or a coolant 50/50 mix, but modern engines and cooling systems that are in good condition are not affected by the increased viscosity.

The other benefits of Evans:

· Totally non-corrosive
· Does not break down over time
· Operates at low pressure; therefore, reduced strain on cooling components

Detractions:

· Expensive – For an NSX the cost is approximately $395 including 4.5 gallons Evans Prep Fluid, 5 gallons Evans Coolant, and a Refractometer for determining water content. Does not include labor.
· Requires a time consuming complete flush of all water-based coolants. To see what’s involved it’s best to watch the videos on Evans’ website.
· Low Pressure/Hi Volume Air Pump is required to aid in flushing the system. A towable inflatable water toy hi volume air pump or the discharge side of a shop vacuum will work.
· Filling involves the same venting procedure used for any coolant on an NSX.
Note: For those who are interested in converting their cars to Evans I would be glad to advise in the process I went through for draining and flushing the system in order to remove 100% of the water-based coolant.

TESTING – All testing was done with the coolant tank pressure cap loose.
Test Run #1.

· Outside Temps 86deg, no rain, AC max cold.

· Driving Condition: Normal local traffic (stop & go and up to 55mph).
· Dash temperature gauge @ approximately 187deg (one pointer's width above the 3rd 185deg tic), which is within the normal operating range.

· Cylinder head temperature measured with a TACKLife IT-T05 infrared detector 3 minutes after shutdown indicated 173deg.
Test Run #2.
· Outside Temps 84deg, no rain, AC max cold.
· Driving Conditions: Normal local traffic with the majority of time at 55-60mph.

· Dash temperature gauge approximately @ 187-189deg.
· Cylinder head temperature measured at cam level @ 173-180deg.
· Cylinder head temperature measured just below the exhaust manifolds @ 247deg.
· Coolant temperature measured in coolant tank @ 189deg.
Conditions immediately following shut down.
· Cylinder head temperature measured at cam level @158deg.
· Cylinder head temperature measured just below the exhaust manifolds @ 215deg.

Final Test Run #3

· Outside Temps 94deg, no rain, AC max cold.
· Driving Conditions: Normal to no traffic. 3 hours total with 1.5 hours each way at speeds between 60 & 80mph. With numerous full throttle accelerations and 20 sec run at 140 and another at 120mph.
· Dash gauge never varied from 187-189deg
· Cylinder head temperature measured at cam level @ 193deg.
· Cylinder head temperature just below the exhaust manifolds @ 215 +- 5deg (burned myself too many times on the exhaust system trying to get an accurate reading)
· Total expansion of the coolant from cold to hot resulted in an approximately 1 inch increase in coolant level in the Dali tank.

CONCLUSION
At this point I feel that the testing proved that the coolant works as advertised and was well worth the investment and the time to make the conversion. One interesting observation was when I started the car up after stopping for a 15 min break at our ½ way point. The dash gauge read no temperature increase when the ignition was turned on and when the motor started. Usually when you shut a hot motor down and then restart it within a short period of time the temperature gauge will show a pretty sharp increase in temperature due to the lack of circulation within the hot motor. Temperature will return to normal once the cooling system starts to circulate and cools the motor back down.

If you feel inclined to do your own research this will save you some time. Here are links to an evaluation of Evans by a competitor No-Rosion and Evans UK Response to No-Rosion's evaluation. It’s pretty detailed but it should answer any questions you have.

Additional Photos are available here. Evans Waterless Coolant Conversion

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MotorMouth93 · 7 August 2017

Interesting info! If I hadn't just flushed and refilled with OEM Honda coolant less than a year ago I would probably give this a shot.

Old Guy · 8 August 2017

You are familiar with nucleate boiling and have discussed it, so no need to go over that. As you note, as you increase the conventional coolant to water ratio, the boiling point of the mix is elevated. Coolant vendors advise against increasing the coolant concentration beyond the maximum recommended values. Aside from the viscosity issues you note the change in concentration elevates the temperature for the on set of nucleate boiling. High coolant concentrations raise the point at which nucleate boiling occurred resulting in a general increase in the engine operating temperature.

You have noted that the Evans coolant boils at 375 deg if you operate with the system un pressurized. Conventional 50:50 mix according to your numbers is 257 deg with the pressure cap on. With a boiling point that is over 100 deg higher than a conventional coolant mix, my gut reaction is that the on-set of nucleate boiling will be at a higher block and head metal temperature with the Evan's coolant than with a conventional 50:50 mix. Since nucleate boiling is generally very important in the process of transferring heat from the metal to the coolant, I would think that the elevated boiling point of the Evan's coolant is going to raise the average engine temperature ?

furinax · 8 August 2017

This is really cool. I wonder if they used a FLIR camera they could show the heat changes before and after Evans' coolant conversion. What are the alternatives to such a system though? Is there evidence that normal driving conditions (such as a 2 hr road trip) would constitute film boiling?

I may replace my coolant hoses soon but this seems like a big overhaul. This is the first time I am hearing of such a system.

nsxspdfreak · 8 August 2017

Old Guy said:
You are familiar with nucleate boiling and have discussed it, so no need to go over that. As you note, as you increase the conventional coolant to water ratio, the boiling point of the mix is elevated. Coolant vendors advise against increasing the coolant concentration beyond the maximum recommended values. Aside from the viscosity issues you note the change in concentration elevates the temperature for the on set of nucleate boiling. High coolant concentrations raise the point at which nucleate boiling occurred resulting in a general increase in the engine operating temperature.

You have noted that the Evans coolant boils at 375 deg if you operate with the system un pressurized. Conventional 50:50 mix according to your numbers is 257 deg with the pressure cap on. With a boiling point that is over 100 deg higher than a conventional coolant mix, my gut reaction is that the on-set of nucleate boiling will be at a higher block and head metal temperature with the Evan's coolant than with a conventional 50:50 mix. Since nucleate boiling is generally very important in the process of transferring heat from the metal to the coolant, I would think that the elevated boiling point of the Evan's coolant is going to raise the average engine temperature ?

Interesting. It's been 22 years that I've been away from nuclear power so you're really making me dust the cobwebs off the grey matter. Linear Heat Generation Rates (LHGR). Onset to Transition Boiling. Critical Heat Flux (CHF) all stuff I haven't talked about in a long time. Nucleate Boiling is the most efficient way of transferring the most energy into the coolant stream; however, even though Nucleate Boiling may occur in a IC engine the current engine cooling systems are not designed to use nucleate boiling as a method of transferring heat. As IC motors become smaller, more efficient, more powerful and run hotter engineers are doing research in more efficient cooling systems that can use Nucleate Boiling effectively. This would include variable speed cooling pumps that do not rely on engine RPM. I can't say for sure what exactly happens inside a motor, but without proper temperature monitoring throughout the motor and a variable coolant flow control system to maintain nucleate boiling and prevent film boiling I would venture to say that no boiling of the coolant is best.

nsxspdfreak · 8 August 2017

furinax said:
This is really cool. I wonder if they used a FLIR camera they could show the heat changes before and after Evans' coolant conversion. What are the alternatives to such a system though? Is there evidence that normal driving conditions (such as a 2 hr road trip) would constitute film boiling?

I may replace my coolant hoses soon but this seems like a big overhaul. This is the first time I am hearing of such a system.

I wish I could have used a FLIR before and after. Assuming the cars cooling system is working properly I would guess that the only time film boiling could occur is following shut down of a hot motor. See my response to Old Guy.

Honcho · 16 August 2017

I've always been interested in Evans for the NSX. I think we would need track testing though, as that is when the stock cooling system is truly stressed (ask me how I know

). Willow Springs testing in summer would be ideal...

nsxspdfreak · 16 August 2017

Honcho said:
I've always been interested in Evans for the NSX. I think we would need track testing though, as that is when the stock cooling system is truly stressed (ask me how I know ). Willow Springs testing in summer would be ideal...

So far so good with the product, but I would be interesting in seeing the results on the track too. Unfortunately I won't be returning to the track in the immediate future.

MotorMouth93 · 31 May 2018

I've been doing more research on waterless coolant lately and remembered this thread. I want to add this for anyone else thinking about doing this in their NSX (or any other car).

You didn't take temperature readings on the engine before making the switch, and frankly that's the only piece of information that's important. You don't have to look far to find reports of cylinder head temperatures increasing rather significantly after making the switch.

The cooling systems in cars are designed to keep the coolant within a specific range of temperatures, you can put literally any liquid into the cooling system and the car would do it's best to keep the fluid within the specified temperature range. The key thing here is that it's the fluid temperature. Just the fluid. Not the cylinder heads, not the sleeves, not the oil, or anything else, just the fluid in the cooling system. This works with 50/50 because the relationship between the coolant temperature and the engine temperature is known, but when you change the properties of the coolant, you change the relationship between coolant temperature and engine temperature.

Engines are designed to run in a very narrow temperature range, changing the coolant without changing anything else WILL change the temperature range in which the engine operates. There's no way around this.

I don't know about any of you, but that's not something I want to play with on an engine as expensive as a C-series to rebuild. There's a reason Ferrari, Porsche, etc. have not switched to waterless coolant in their ultra high performance halo cars.

Also, Evans failed to counter any point made by No-rosion and just came off like arrogant douchebags.

nsxspdfreak · 31 May 2018

MotorMouth93 said:
I've been doing more research on waterless coolant lately and remembered this thread. I want to add this for anyone else thinking about doing this in their NSX (or any other car).

You didn't take temperature readings on the engine before making the switch, and frankly that's the only piece of information that's important. You don't have to look far to find reports of cylinder head temperatures increasing rather significantly after making the switch.

The cooling systems in cars are designed to keep the coolant within a specific range of temperatures, you can put literally any liquid into the cooling system and the car would do it's best to keep the fluid within the specified temperature range. The key thing here is that it's the fluid temperature. Just the fluid. Not the cylinder heads, not the sleeves, not the oil, or anything else, just the fluid in the cooling system. This works with 50/50 because the relationship between the coolant temperature and the engine temperature is known, but when you change the properties of the coolant, you change the relationship between coolant temperature and engine temperature.

Engines are designed to run in a very narrow temperature range, changing the coolant without changing anything else WILL change the temperature range in which the engine operates. There's no way around this.

I don't know about any of you, but that's not something I want to play with on an engine as expensive as a C-series to rebuild. There's a reason Ferrari, Porsche, etc. have not switched to waterless coolant in their ultra high performance halo cars.

Also, Evans failed to counter any point made by No-rosion and just came off like arrogant douchebags.

Not that I'm doubting you, but show us the reports on increased cylinder head temperatures you're referring to.

MotorMouth93 · 3 June 2018

The No-rosion report linked in the OP.

Evans has an incredibly easy way to show that their product does what they claim: they get baseline temperature readings under various load conditions with regular 50/50 coolant in a variety of engines and vehicles, then swap in their coolant and repeat the tests. If temperature increases are minimal to nonexistent, then their claims are true.

But they don't, they just provide us with theoretical garbage that sounds cool with nothing to back it up. It's like they stopped at the hypothesis stage when it came to testing.

The burden of proof falls on Evans since they are the ones making the claims.

I would love to eat my words and switch to Evans, having a low pressure cooling system could potentially save me loads of money in the BMW since E39s are notorious for coolant leaks and catastrophic cooling system blowouts, but I'm not willing to be a test subject for something that could significantly shorten the life of my engines.

Evans High Performance Waterless Coolant Evaluation

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