Frans=2CI have no reason for believing that the Evans has actually lowered
my cyl temps. In fact=2C it was very evident that the both #2 and #4 cylin
ders when using Evans were hotter. I confirmed this using my hand held the
rmometer. Without manufacturer driven research we are all just guessing.
I must agree that the Evans claims in large auto and truck engines and rad
iators is very accurate. However=2C you are spot on that their performance
(especially in the motorcycle world and ATVs) is probably checkered at bes
t and the company has made numerous changes=2C primarily due to the vast nu
mber of differences in equipment=2C coolers=2C water flow rates=2C etc. I
would hope that the Evans folks are getting the feedback they need. Right
now=2C I cool my trigear very well even in summer temps using 50-50 glycol.
Of course one never uses glycol pure. I just use distilled water with Ha
veline coolant or buy the premix and all has been well. An acquaintance o
f mine which maintains WWII era engines has used Evans=2C and found the rad
iator size on his test bed needed more air to keep the temps down. Like us
=2C he was convinced that he would run at near zero pressure=2C which is mu
ch safer for him in the event of a leak on the engine test stand. Also he
was interested in the lubrication and non corrosive aspects of Evans in his
antique engines. However he is just not seeing better performance from th
e coolant in practical use. He looked at the auto community and because th
e specific heat of Evans is not a good as gylcol/water the radiator perform
ance is poorer. (His tests are now over three years old.)He put me on to t
he research done by one of the Jaguar car clubs=2C and it is worth a read b
ut settles nothing with Evans use:http://www.jcna.com/library/tech/tech0011
.html Comments from some SoCal racers I knew in Apple Valley (Off road rac
ers) follows:"Evans coolant is 100% propylene glycol...no water added. (Not
e from Bud=2C that Evans has gone to a mixture of propylene and glyol to th
in the coolant so it is no longer pure.) Cool thing is it
doesn't boil until 360F. Thats great when you think about localized boiling
around the cylinders causing hotspots with conventional...with Evans there'
s no
way you're going to get hotspots in the combustion chamber that can possibl
y
cause knock. Bad thing is propylene glycol's specific heat isn't all that g
reat.
That effectively makes your radiator act like its smaller than it really is
.
That also means that when your engine makes a fixed amount of heat the Evan
s
coolant temps will rise more than water will. That's all fine and dandy whe
n you
remember that it won't boil until 360F...it has plenty of overhead. The bad
thing is the fans run more often than they should since the stock computer
thinks you're getting hotter than you should be. The other bad thing is you
r oil
temps go up from the extra heat in the block so you need a nice big oil coo
ler
to manage things. Granted Mobil 1 says its good for 400F but I know most ro
ad
racers shut things down at 300F. Other negatives to the Evans coolant are t
he
cost and the large expansion rate range of the fluid with temperature swing
s." Many of these desert racers operate at outside temps near 120F and us
e pure water with an additive to break the surface tension as pure water is
not flamible=2C and really moves heat fast. They believed Evans was the a
nswer to running with zero pressure caps=2C but cooled to that now. Anyway
=2C although there may be no local boiling in the head with Evans=2C the en
gine water pump moves the heat faster away from the head and radiator using
50/50 glycol. Since the Rotax goes well over 1000 hours without head and
valve problems=2C I see no reason to jump on the Evans band wagon=2C and sp
end the time and money to research new radiator sizes and flow rates any mo
re. Even Lockwood Aviation=2C (one of the largest Rotax distributors and R
otax Powered LSA dealers) has stopped using Evans in their planes. Lifetim
e coolant is not really necessary when in 5 years we change the hoses anywa
y and must go through the mess of trying to catch and reuse the coolant. Ju
st my opinion...I'm a 50/50 guy for now. Best Regards=2C
Bud Yerly > Date: Sun=2C 26 Feb 2012 12:55:18 +0100
> From: frans@privatepilots.nl
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Laminova heat exchanger and Evans coolant
>
>
> Hi Bud=2C
>
> > I have used the Evans in a stock trigear and have found my CHTs were
> > about 15 degrees cooler with the glycol.
>
> Then that trigear was suffering from micro-boiling with the previour
> coolant=2C otherwise it is quite impossible. The heat transfer rate of
> Evans is lower than that of water based glycol=2C no way it can improve
> over that. The *only* difference with Evans is the much higher boiling
> point. This eliminates micro boiling and it allows you to operate the
> engine at a *higher* temperature (also according to Rotax). So far the
> concensus on this forum has been that the CHT's get hotter when using
> Evans=2C forcing quite some people with a marginal cooling setup to rever
t
> back to 50/50.
>
> > I cannot imagine that the Evans would be too thick for the Laminova hea
t
> > exchanger as the coolant is basically the same viscosity of the Ethylen
e
> > glycol.
>
> Pure ethylene glycol is too thick as well=2C but you are supposed to mix
> it with water.
>
> Maybe I'm living in a colder climate. On te Evans network I found in
> their FAQ a description of exact this problem "some engines overheat
> immediately following a cold start due to the lower viscosity of cold
> Evans coolant". They offer modified coolant pumps=2C thermostats=2C etc.
And
> they have a new type of coolant designed for motorcycles with improved
> viscosity so it flows better through fine radiators.
>
> > I hope not to insult you=2C but there are three or four types of Evans
> > coolants.
>
> I know. There are even more. I have tested the factory recommended NPG+.
> But now there appear to be two versions of this NPG+. Read on:
>
> > To my
> > knowledge=2C there is no viscosity difference with any of them and all
> > should work with the Rotax and Liminova.
>
> Yes there are differences=2C to address exactly this problem. I found a
> table somewhere but their website is a mess=2C I have to search for it
> again. Take for example their NPG-R:
> On one of their websites:
> "NPG-R NPG-R is specifically formulated to handle the extreme conditions
> of racing and high performance automotive=2C marine and motorcycle
> applications. *The reduced viscosity of NPG-R makes it more compatible
> with small tube copper-brass radiators* while providing the superior
> cooling of Evans Waterless Coolants."
>
> Also=2C if you Google you will find references to a product called NPG+C.
> Note the "C". Interesting is that it is announced as a product with
> lower viscosity=2C but a preview is not possible and if you click the lin
k
> a page with a different contents is shown. It appears that Evans just
> removed the references and there are indications they silently replaced
> the NPG+ with NPG+C.
> If you carefully look at the picture of the can you will see the "C"
> behind the "NPG+". My can looks exactly like this but doesn't have the
> "C". They now tend to name it "High Performance Coolant" and the can
> suggests that it is the formerly called NPG+ but it isn't=2C it carries
> the "C" behind the name.
>
> Maybe Evans is silently replacing their product line and tries to avoid
> liability claims from people who experienced problems due to the lower
> viscosity. There is a lot of obfuscation going on there. They openly
> claimed that the NPG-R variant has a higher viscosity but if you look in
> the separate product descriptions they are all listed with the same
> viscosity=2C which contradicts a lot of other information.
>
> Anyway=2C there are lots of descriptions on the net about pump cavitation
=2C
> i.e. the coolant pump drawing itself empty due to the too bad viscosity
> of Evans. With a stock radiator it might work=2C but with a Laminova it
> won't. At least not with MY can of Evans NPG+=2C the one without the C
> behind the name.
>
> One example:
> "I just got an email from Evans Cooling. They said that the problem with
> NPG+ was that it was the viscosity in cold weather coupled with heater
> core passages are so small. This prevented the heater from getting hot.
> Their solution is to use their new product that addresses this problem:
> NPG+C now only available only from their Potstown PA office=2C same price
."
>
> > Are you using the S34 heat exchanger? That is what I thought about test
ing.
>
> No=2C a different one (I can look it up if you want)=2C a special
> lightweight version. And don't forget you have to plug the center hole
> due to the low flow of the Rotax engines. Don't ask me how I know.
> If you go testing this=2C keep in mind that it places a greater demand on
> your water cooling. So if this is marginal=2C fix it first. I abandoned
> the stock thick radiator and its ducting completely and have used an
> angled thin radiator instead.
> For the oil cooling part=2C keep in mind that the efficiency of the oil
> cooler drops of when delta-T becomes too low. It is hard to cool the oil
> down to 120C if the coolant is 115C. If you like to be able to operate
> the engine near the upper range of its thermal design you still need
> some sort of after cooling for the oil. I have used a very small
> radiator for it (1/4 size of the stock radiator) and feed it air via a
> very small opening through a wedge diffuser.
> Benefits of this cooling layout are the higher efficiency due to
> elimination of a lot of cooling drag=2C superfast oil heat up time withou
t
> thermostat=2C and it is impossible to overheat the oil due to the sharp
> increase of heat dissipation of the Laminova when delta-T rises.
> An in flight adjustable cowl-flap is a must with this design.
>
> Once you get it working it is a hell of a cooling system=2C with minimal
> warm-up time=2C an extremely broad OAT range=2C impossible to overheat=2C
and
> with far less cooling drag than the conventional setup. Expect to see
> some additional knots as a result.
>
> > It almost sounds like the water pump inlet hose was kinked after the
> > flush and blocked the flow. Easy done.
>
> There was no kink and there was no air lock. I actually didn't touch the
> cooling system at all but just opened the drain at the bottom of the
> radiator=2C and once the Evans was out I refilled it with the old coolant
=2C
> and suddenly the cooling system was working again.
> To empty the overflow bottle I used a small hose to syphon the stuff
> out=2C what I noticed was that the flow of the Evans through this hose wa
s
> far less than what I got when siphoning out the 50/50 coolant. So much
> for the viscosity. BTW OAT was about 8C when I was doing all this (dunno
> what this is in F=2C but it is pretty cold).
>
> Frans
>
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