I stumbled on a website for Rotax airplane engines (I know, not the same animal as the Rotax in our DS's) that is selling Evans waterless coolant.

Supposedly, since it's waterless, corrosion and boilover (boils at 375F) are no longer issues, as well as the need to replace the coolant. They recommend dropping the PSI of the system down from 16psi to 7psi, which should also help all the components in the cooling system live longer.

It looks like it costs around $40 a gallon after shipping. It would be cheaper in the long run that replacing coolant. My guess is that you would need to get the cooling system really clean before switching over, which would add more cost.

I guess there are two formulations. NPG-R is lower viscosity, but does not carry the same lifetime warranty. http://www.hrpworld.com/index.cfm?tpc=Evan's_NPG-R_Super_Coolant&form_prod_id=683,587_3160&action=p roduct

NPG+ is higher viscosity, with no annual change requirement. http://www.hrpworld.com/index.cfm?tpc=Evan's-NPG+-Super-Coolant&form_prod_id=3415&action=product

Anybody try it?

Looks like it's cheaper than engine ice, and possibly perform similarly.

I went digging some more on Evan's website, and they also make a powersports product just for ATV's and motorcycles.

 

The Powersports product comes in half gallon bottles for ~25$ plus shipping if you can't get it local. I think I'm going to pull the trigger and give it a try. The DS typically does not overheat, but I find when I do WOT down a sand wash for a couple of minutes in high gear that the engine smells hot and will bubble a little coolant into the reservoir. Its not actually boiling over, but I guess I hold back because I don't want it to boil over. With the Evans, since it's waterless and boils at ~ 375F, you should never get in a situation when you boil the coolant in the head, create steam pockets, and localized hot spots. At that point, that local area of the engine is not being cooled because the steam froms an insulative barrier between the coolant and the metal. Theoretically, this should not happen with the Evans coolant.

No possibility boil overs (without major engine damage 1st!) , no possibility of electrolisys, it will not support corrosion, never needs changing, and can be operated at lower (7 psi) or no cooling system pressure which should make the radiator and hoses last longer, no pump cavitation, no silicates to degrate waterpump seals, and it's non-toxic (you could safely drink it. Probably give you the squirts, though)

If you are in a bind and have to add water to the system, you can, but you will have to drain and refill with fresh coolant.
I would rather try to purchase or modify my stock rad cap to have some pressure in the system (4-7 psi rather than 16 psi stock). I guess you can drill the rivet out and have a zero pressure system, but I would think that with a high rpm engine that is bouncing around, you would get some coolant loss. I hope I can either cut the spring, or heat it up part of it to take out some of the spring tension.

I bet you can even skip the $35 flush that Evans recommends. By flushing the system with water 1st, and then removing the temp sensor, water pump , all the hoses and radiator, blow them out with compressed air and leave the system open for a couple of days. If there is any small amount of water left in the system, I bet if you left the rad cap off while going on a mild ride, you would allow any remaining water to evaporate out of the system.

Evans is not really clear on some things, but they seem to indicate that get the best performace out of the coolant change, that sometimes you need to swap the waterpump, thermostat, and change the coolant sensor to come on at a higher temperature. I believe they suggest this to achieve the 10% increase in fuel efficiency when using this product. Since it won't boil until 375F, you can safely raise the fan control temp and the efficiency of not generating electricty to power the fan as much is where the fuel savings comes in. Not much of an issue on a quad though. You can do some math and add a resistor to the coolant sensor circuit to have the fan come on at a higher temp. You actually get better engine efficiency and can tune for more HP the hotter an engine runs, as long as you keep it out of detonation and from overheating...

Anybody see any holes in my process?