It would seem that there haven't been any failures due to the increased metal and oil temps seen with Evans coolant. Someone please correct me if I'm wrong.


So it appears that most overheating problems are due to the extremely high localized temperatures that occur due to boilover.
Since water has superior heat transfer abilities, why not simply increase the pressure of the cooling system?

from http://www.centuryperformance.com/coolingsys.asp :

1. Pure water in a cooling system will boil (at sea level) at 212° F
2. For every pound of pressure exerted on the coolant in the system, the static boiling point of the coolant is raised by approximately 3° F.



Say we want our water to resist boiling at 270° F, that's (270-212)/3 = 19.3 psi needed. A 20psi cap should work fine. Assuming we're running an 80/20 EGW mix, our boiling point will be raised even higher. Can our coolant seals handle this?

-s-

 

Its not so much the coolant seals I would worry about that cant handle a high pressure like 20psi. I would be more concerned with all the hose connections leaking or just hoses bursting.

 

Hoses are relatively easy to upgrade, compared to replacing coolant seals.

-s-

 

I agree with Scotty.

The temperature you guys keep talking about (220 -230F) is only important because that is where standard coolant mixtures begin to fail (vaporize) causing hot spots and then possibly detonation or warping. Pressure is only applied to the system to increase the boiling point but it is of course a finite option. (Raises the boiling point from 212 to 230-240 max)

The benefit of evans is that even at zero pressure its range of temps far exceeds the range seen and it can continue to cool the engine without vaporizing. Sure its warmer but that is not the problem because it is not vaporizing.

Coolant failure = vaporization not a certain temp on a temp guage in a coolant system.

 

Yup, root cause of most o'heating conditions is loss of pressure ... could be internal through seals or cap, or external. With 16 psi cap, BP of water is 252F and for 50% egw it is 267F. Even with 220-230F on gage, still have nice margin of 37F with 50% mix, to be sure local vapor is quickly condensed. But the coolant has low elasticity, so slight leak will drop the pressure quickly ( it is the expansion of the coolant through the cap that initially creates the pressure, not the heat ). The BP of 50% mix is only 226F if all pressure is lost. So with lower pressure, more boiling can occur, and uncondensed vapor starts replacing coolant .... gage then jumps. AST is not designed to compensate for any significant leak. In theory, you would need a small pump injecting renewal coolant at just under cap pressure, to prevent pressure loss and boiling cycle, with a coolant leak. Best part of NPG+ is that only very low pressure is suggested, and boiling is not an issue.

http://www.mgb-stuff.org.uk/coolingtext.htm (BP Table)

 

Last two motors I had, both failed through warped housing and failed o-ring seals.

One thing I have noticed with water or NPG+ is that the stock turbos retain enormous amount of heat such that localized boiling occurs even with a 19psi cap on for water and hence the gurgling sound after shut down.

I can't believe I'm still fiddling with a car over 12 years old. Damn I must be an old fart.

 

LOL No, there just hasn't been anything offered by anyone (let alone Mazda) in the last 12 years worth giving up your FD for...that's remotely affordable (spare me the exotic solution :P)

I don't think the FD is the only car with cooling issues once you are at the track (especially when you've added 50% more power to the car). As you up the HP (HEAT) on your car, you just need better and better cooling, and is it such a bad thing to need a break within a day's time at the track?

I still would like to conclude which is better for my car, but I'm still scratching my head...

 

Yes but compared to what other forces the coolant seals face 20psi vs. 0 psi is not going to make a bit of difference. 20psi is going to have a much greater effect on things like the water pump and hoses than it will on the coolant seals.

 

OK thanks Tom, I'm glad to hear that the coolant seals can take the extra pressure. In the past, I've read about the coolant system recall that involved a lower-pressure radiator cap, and that made me wonder if the problem was coolant-seal related.

If better cooling is just a pressure cap and upgraded hoses away, that would make me a very happy person... I'll have to research the cost of upgrading the pressure of the EGW system vs. converting to Evans.

-s-

 

I still wouldnt upgrade hoses and cap to run higher pressure. Any leak is going to be that much more messy and more likely catastrophic with running a higher pressure. The higher pressure the more quickly fluid will exit through any small leak.

 

I got a reply back from Evans. NPG+ and NPG-R have the same specific heat (0.66 Btu/lb/F at 212 F).

 

Sometimes I get the feeling that one can run 0w30 oil in the cooling system and get the same results of the Evans.

 

I've run the evans in my 7 for years without issue and loved having near zero pressure on my hoses and connections plus zero chance of a hot spot due to local boiling of water based coolants.

It should be a simple decision ... if your egw mix can keep coolant temps at or below 210F then don't bother with Evans unless you like the idea of running a zero pressure system that never needs replacing and will not corrode your internals. If you see higher temps, then Evans and/or other system improvements should be considered. Evans by itself is not the solution, it merely eliminates some fundamental weaknesses of water based coolants at the expense of slightly higher bulk coolant temps.

 

No, but you can run straight Sierra antifreeze and get the exact same thing.

 

So the conclusion is that Evans is BS?

Even more so since u can't mix water with it if ur cooling system happens to need a refill in the middle of nowhere?

 

Have you emailed or called Sierra to make sure a 100% sierra mixture is ok to run on your car? You should verify your ideas before stating them as fact.

 

Not necessarily. The conclusion is: If you run your car where it has the possibility to run high temperatures for prolonged periods of time (i.e. tracking the car), Evan's can be a benefit for that type of application.

On the street, Evan's really has no advantage to standard coolant/water mix.

That's what your insurance company and their tow service is for... Too good thing about Evan's is that you can run a lower/zero pressure cooling system. It will put less stress on the hoses/clamps (theoretically), thus making bursting/splitting hoses a much less occurrence.

Personally, after going through this thread, I'm seriously considering runnnig Evan's after my rebuild. My car is mainly a track car so the increased boiling points and lower pressure seem to fit my needs.

 

Insurance towing does have a limit on the miles. If you are so lucky to be beyond the range then your pocket book will be on a diet.

Even though Evans may run greater temp extremes I'm still not convince that Evans would do a better job in transfering/dissipating heat like traditional coolant.

Look at pure coolant. Greater temp limits if you use it pure, but can anyone tell me why water should be added?

 

That's basically the point. Evan's can be beneficial in an application where heat just can't be dispersed faster than it's building (i.e. on the track running hard for 20-30 minute sessions). Given a situation where heat dispersal can effectively reduce temperatures, Evan's offers no benefit.

 

If heat can't be dispersed faster enough wouldn't that be bad?

Side housing would heat soak and expand more often, thus shortening the life of the seals.

What about increase detonation risks?

 

Yes, hence an application for Evan's to be able to handle the higher temps. Too much boiling of the coolant make it ineffective at absorbing heat. You can increase it's boiling point by raising the pressure for the standard coolant/water. However, that puts more stress onto the system as a whole. Evan's claim to to handle higher temps without the need for the extra pressure on the system.

More things come into play about detonation than just coolant temps (like intake charge temps).

 

Ain't greater boiling point and heat dissipation 2 different attributes?

Can't you have higher boiling point, but terrible heat dissipation at the same time?

 

I can't believe you even MENTIONED running regular coolant WITHOUT water----just STRAIGHT antifreeze!!! Water is what transfers the heat----PERIOD!!! Antifreeze merely ENHANCES the water's properties of heat tranfer by raising it's boiling point and lowering it's freezing point, as well as giving the water lubricating properties for the waterpump and anti-corrosive properties for the cooling system. Without water, the antifreeze cannot transfer the heat from the engine.
Basic automotive knowledge.

 

Yeah, that's is the point I'm trying to make.

 

What point? Evan's is not straight standard coolant so there is no comparison. All the points for or against it are pretty much already highlighted in this thread. Basically, you have to decide whether it's the right application for you or not.