Thoughts on Evans Coolant

[Dorsal]

So while chasing potentially high CHTs (likely a instrumentation issue) I am considering changing over to Evans water-less coolant. It seems to me that if my engine is running hot I should use Evans to prevent boiling. Another TKF member pointed out that if you burn mostly 100LL you want the engine to run hotter so if my engine is running cool I should use Evans to get it to run a little hotter. My logic is that if you burn 100LL Evans is always a better choice.
Anybody see flaws in this thinking?
Also have others switched over, any issues or tips?

[rwaltman]

... considering changing over to Evans water-less coolant. ... any issues or tips?

I have no first hand experience, but did a lot of reading around the time I bought my KF. (Because of flirting with a Zenith CH701, which had a Subaru engine running Evans coolant from the start. Decided against it because of the engine's weight.)

The one thing I didn't like is that while Evans allows higher operating temperatures, it also forces higher operating temps because it doesn't have the same heat-carrying capacity than water.

I found it interesting that their web site does not mention the coolant's specific heat figure. [ A google search for site:www.evanscooling.com "specific heat" brings no results ]

Also read some user posts (not in aviation forums) mentioning that, although their engine's cooling system run fine, they were concerned about what other things may have a reduced life expectancy because of the higher temps.

On the other hand, the promise of no corrosion and no electrolysis problems is a definitive plus.

I would try posting in other places to find people already running Evans coolant on '912s.

Roberto.

PS: Just found this: http://www.aviationpros.com/article/...ngine-coolants

[cubtractor]

I used Evans when I initially rebuilt my plane and installed the LCH heads on my Jabiru. It worked great and did seem to run hotter with the Evans. I am running an electric water pump so in my case, since the Evans is a thicker fluid than standard 50/50 glycol mix, it is harder to pump than standard coolant and draws more amps. Rotax shouldn't have the pump issues. My system cools well enough that I switched back to 50/50 glycol due to the fact that if I were to have a cooling issue at this point it would have to be from a mechanical failure of some point at which the engine would get hot with either coolant. I regained some amps back to my charging system as well and the engine does run about 15 degrees cooler with 50/50 glycol.

I do run ethanol free 91 octane which I am still able to get here in southwest MO, and not 100LL.

I do think Evans is a good product and this is not a Rotax I know, but just some insight from my experience with Evans

[Dave S]

Dorsal,

Running the 912ULS in our series 7, I have only used Evans since first starting the engine, based on the Rotax recommendations at the time. I have not had any reason for concern. I figure the higher boiling point is insurance.

At least theoretically, a gasoline engine will be more efficient at a higher operating temp with the limitations normally being the oil, coolant, materials heat tolerances.

Another person on my home field started with Evans and went to 50/50 Ethylene glycol - that is in a KF V with the 912ULS. His experience indicates the engine ran a little cooler with the 50/50 Ethylene glycol.

I have no plans to do other than to continue to use Evans.

Sincerely,

Dave S
KF7 Trigear
912ULS Warp Drive

[Dorsal]

This is the quote from AV8R3400 that I was referring to.

"It is absolutely imparative that when you run 100LL in a 912 you keep your temps up to burn the lead off. Even with a lead scavenger additive. Several comments on this at airventure."

So it is because Evans has less heat capacity that it might be a better choice if, like me, you burn primarily 100LL.

[Timberwolf]

I think there's some confusion with engine operating temperature and combustion temps. By running higher EGT's and an ideal AF ratio (rather than an enrichened mixture) is what is going to burn off the lead in 100LL and not allow precipitates to form in your engine. Otherwise running a rich mix and cool egt's can form the deposits that you're so afraid of. Engine operating temps can aid in running the engine where it is most efficient and is able to keep the deposits to a minimum, but I wouldn't say that is the only factor. Without going into the thermodynamics of it, an engine runs more efficiently the warmer it is (GM performed some tests running duramax engines very hot and were able to achieve almost no diesel knock and great efficiency) however, the materials are the limiting factor in the equation since we all know a perfect system doesn't exist.

I personally would run the Evans if Rotax approves it. The higher temps are increasing eff. and will assist in ensuring you are burning off the lead rather than having it collect inside your engine. Hopefully all of that makes sense.

[rwaltman]

I personally would run the Evans if Rotax approves it

For certain installations it is not only approved, it is required to use a waterless coolant.
See EASA airworthines directive AD_2007_0155 and Rotax service bulletins SB-912-043 R2 and SB-914-029 R2 (They don't specify a brand, of course)

And here Aircraft Spruce will happily sell it:
http://www.aircraftspruce.com/catalog/eppages/evans.php

Roberto.

[jdmcbean]

A note regarding EVANS.. The suggestion is that if you do not need it do not use it... It does not cool as well.

On a side note.. the new 912iS actually recommends 50/50 not EVANS.

[kmach]

Hi, I originally used evans coolant , I was running a little hot on the hot

summer days. I switched to 50/50 mix when I changed hoses, the

temps with 50/50 mix were consistently 25 degrees F cooler , cht's are

now215-220, coolant around the 200 F ,the coolant is cooler since it's sensor

is about 12"s after the expansion tank before going into the rad.these temps

are on a 80F day cruise 5100 rpm.

[Av8r3400]

When talking about keeping your temps up with 100LL I should qualify that as not necessarily meaning the indicated temps. I mean the combustion temps. This was discussed as not loafing about at 4000 rpm but keeping the power levels up at like 5000-5200 as much of the time as possible.

As to Evans, I'm not a fan. Simply put its expensive, difficult to find in an emergency, and doesn't cool as well. It appears to me to be a bandaid way of dealing with a cooling problem.