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frans(at)privatepilots.nl
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 Posted: Sat Feb 25, 2012 8:50 am Post subject: Laminova heat exchanger and Evans coolant |
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Hi everyone,
As some of you know I have drastically changed the cooling system of my
914 powererd Europa and achieved perfect cooling without having to
resort to more and larger openings in the cowling. Even better, I think
I have only about 50% of the original air flow left at maximum cowl flap
angle and about 10% of this during the cruise. Less cooling air is less
cooling drag, which is a significant percentage of the total drag of an
Europa. It is one of the keys why I can easily cruise at 140 knots with
my hi-top tri-gear. (Sorry, still didn't got time to write the promised
article about this).
So, with so much cooling overcapacity I thought to make the transition
from 50/50 to Evans coolant. Reason for that was to be able to allow the
engine to run slightly hotter (good for the efficiency) and to have zero
pressure in the cooling system (which is good in case of a leak).
One key element in my cooling system is the Laminova oil to water heat
exchanger. This marvel has very fine oil and coolant passages to ensure
good heat transfer.
After swapping the 50/50 coolant for Evans I started the engine... and
it was interesting to see the CHT's to increase very fast to 100C while
the coolant sensor was still at ambient temperature. Coolant flow in the
system appeared to be about zero.
I thought of an air lock initially, but after much rocking and
disconnecting hoses at key locations I was quite sure that I didn't have
an air lock (I never had to resort to any of such trickery during the
cooling experiments with 50/50).
So, that Evans stuff simply appears to be too thick for the tiny canals
of the Laminova heat exchanger. When the oil finally warms up by itself
(without the use of warm coolant as usually was the case, so this takes
a long time) the flow improves somewhat, but the best I got was a 30C
difference between the CHT and coolant (on the ground at low power). It
is not flyable. With 50/50 the temperature difference between the CHT
and coolant is almost nothing, indicative for sufficient coolant flow.
So, my question to anyone who has or is using Evans coolant: Did you see
a large difference between the CHT's and coolant temperature? Has anyone
ever tried to use Evans in combination with a Laminova/Mocal heat exchanger?
On the Evans website a new type of coolant is announced, with higher
viscosity especially for motorcycles that have smaller radiators with
smaller canals. (Apparently there are more folks having problems with
the regular thick Evans stuff). Has anyone tried that in an Europa? And
more importantly, am I allowed to use it in my Rotax?
I'm back to 50/50 for the moment (too bad for my dewatering efforts
prior to pouring in that Evans stuff).
Anyone interested in my can of Evans NPG+? Used only once! Never flown
with it.
Frans
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budyerly(at)msn.com
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| Posted: Sat Feb 25, 2012 3:50 pm Post subject: Laminova heat exchanger and Evans coolant |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Frans,
I have used the Evans in a stock trigear and have found my CHTs were about 15 degrees cooler with the glycol.
I am as perplexed as you why the difference in the coolant temp probe performance.
I cannot imagine that the Evans would be too thick for the Laminova heat exchanger as the coolant is basically the same viscosity of the Ethylene glycol.
Are you using the S34 heat exchanger? That is what I thought about testing.
Discussion:
I would expect you to see what I and others have seen with the Evans, that is about a 15 degree CHT rise as the heat transfer rate of the Evans is slightly less than the glycol. For a properly set up trigear though, that would not be anything worth worrying about. The oil temp should be nearly coolant temp once warmed up.
I hope not to insult you, but there are three or four types of Evans coolants. Are you using the heavy duty (yellow NPG), high performance (green which I used), NPG+, or Powersport which I think is NPGR. To my knowledge, there is no viscosity difference with any of them and all should work with the Rotax and Liminova.
I do know that the glycol cooler must be free of water or things to to hell until the water evaporates. It was like oil and water but the Rotax still cooled.
It almost sounds like the water pump inlet hose was kinked after the flush and blocked the flow. Easy done.
Bud Yerly
Europa Tech Support.
---
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frans(at)privatepilots.nl
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| Posted: Sun Feb 26, 2012 3:58 am Post subject: Laminova heat exchanger and Evans coolant |
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Hi Bud,
| Quote: | 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, otherwise it is quite impossible. The heat transfer rate of
Evans is lower than that of water based glycol, 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, forcing quite some people with a marginal cooling setup to revert
back to 50/50.
| Quote: | I cannot imagine that the Evans would be too thick for the Laminova heat
exchanger as the coolant is basically the same viscosity of the Ethylene
glycol.
|
Pure ethylene glycol is too thick as well, 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, thermostats, etc. And
they have a new type of coolant designed for motorcycles with improved
viscosity so it flows better through fine radiators.
| Quote: | I hope not to insult you, 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:
| Quote: | To my
knowledge, there is no viscosity difference with any of them and all
should work with the Rotax and Liminova.
|
Yes there are differences, to address exactly this problem. I found a
table somewhere but their website is a mess, 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, 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, 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, but a preview is not possible and if you click the link
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, 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, which contradicts a lot of other information.
Anyway, there are lots of descriptions on the net about pump cavitation,
i.e. the coolant pump drawing itself empty due to the too bad viscosity
of Evans. With a stock radiator it might work, but with a Laminova it
won't. At least not with MY can of Evans NPG+, 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, same price."
| Quote: | Are you using the S34 heat exchanger? That is what I thought about testing.
|
No, a different one (I can look it up if you want), 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, keep in mind that it places a greater demand on
your water cooling. So if this is marginal, 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, 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, superfast oil heat up time without
thermostat, 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, with minimal
warm-up time, an extremely broad OAT range, impossible to overheat, and
with far less cooling drag than the conventional setup. Expect to see
some additional knots as a result.
| Quote: | 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, and once the Evans was out I refilled it with the old coolant,
and suddenly the cooling system was working again.
To empty the overflow bottle I used a small hose to syphon the stuff
out, what I noticed was that the flow of the Evans through this hose was
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, but it is pretty cold).
Frans
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budyerly(at)msn.com
Guest
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| Posted: Sun Feb 26, 2012 11:47 am Post subject: Laminova heat exchanger and Evans coolant |
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Frans,
I have no reason for believing that the Evans has actually lowered my cyl temps. In fact, it was very evident that the both #2 and #4 cylinders when using Evans were hotter. I confirmed this using my hand held thermometer. Without manufacturer driven research we are all just guessing.
I must agree that the Evans claims in large auto and truck engines and radiators is very accurate. However, you are spot on that their performance (especially in the motorcycle world and ATVs) is probably checkered at best and the company has made numerous changes, primarily due to the vast number of differences in equipment, coolers, water flow rates, etc. I would hope that the Evans folks are getting the feedback they need.
Right now, 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 Haveline coolant or buy the premix and all has been well.
An acquaintance of mine which maintains WWII era engines has used Evans, and found the radiator size on his test bed needed more air to keep the temps down. Like us, he was convinced that he would run at near zero pressure, which is much 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 the coolant in practical use. He looked at the auto community and because the specific heat of Evans is not a good as gylcol/water the radiator performance is poorer. (His tests are now over three years old.)
He put me on to the research done by one of the Jaguar car clubs, and it is worth a read but 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 racers) follows:
"Evans coolant is 100% propylene glycol...no water added. (Note from Bud, that Evans has gone to a mixture of propylene and glyol to thin 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 possibly cause knock. Bad thing is propylene glycol's specific heat isn't all that great. 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 Evans coolant temps will rise more than water will. That's all fine and dandy when 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 your oil temps go up from the extra heat in the block so you need a nice big oil cooler to manage things. Granted Mobil 1 says its good for 400F but I know most road racers shut things down at 300F. Other negatives to the Evans coolant are the cost and the large expansion rate range of the fluid with temperature swings."
Many of these desert racers operate at outside temps near 120F and use pure water with an additive to break the surface tension as pure water is not flamible, and really moves heat fast. They believed Evans was the answer to running with zero pressure caps, but cooled to that now.
Anyway, although there may be no local boiling in the head with Evans, the engine 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, I see no reason to jump on the Evans band wagon, and spend the time and money to research new radiator sizes and flow rates any more. Even Lockwood Aviation, (one of the largest Rotax distributors and Rotax Powered LSA dealers) has stopped using Evans in their planes. Lifetime coolant is not really necessary when in 5 years we change the hoses anyway and must go through the mess of trying to catch and reuse the coolant.
Just my opinion...I'm a 50/50 guy for now.
Best Regards,
Bud Yerly
| Quote: | Date: Sun, 26 Feb 2012 12:55:18 +0100
From: frans(at)privatepilots.nl
To: europa-list(at)matronics.com
Subject: Re: Laminova heat exchanger and Evans coolant
--> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl>
Hi Bud,
> 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, otherwise it is quite impossible. The heat transfer rate of
Evans is lower than that of water based glycol, 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, forcing quite some people with a marginal cooling setup to revert
back to 50/50.
> I cannot imagine that the Evans would be too thick for the Laminova heat
> exchanger as the coolant is basically the same viscosity of the Ethylene
> glycol.
Pure ethylene glycol is too thick as well, 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, thermostats, 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, 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, there is no viscosity difference with any of them and all
> should work with the Rotax and Liminova.
Yes there are differences, to address exactly this problem. I found a
table somewhere but their website is a mess, 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, 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, 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, but a preview is not possible and if you click the link
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, 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, which contradicts a lot of other information.
Anyway, there are lots of descriptions on the net about pump cavitation,
i.e. the coolant pump drawing itself empty due to the too bad viscosity
of Evans. With a stock radiator it might work, but with a Laminova it
won't. At least not with MY can of Evans NPG+, 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, same price."
> Are you using the S34 heat exchanger? That is what I thought about testing.
No, a different one (I can look it up if you want), 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, keep in mind that it places a greater demand on
your water cooling. So if this is marginal, 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, 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, superfast oil heat up time without
thermostat, 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, with minimal
warm-up time, an extremely broad OAT range, impossible to overheat, 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, and once the Evans was out I refilled it with the old coolant,
and suddenly the cooling system was working again.
To empty the overflow bottle I used a small hose to syphon the stuff
out, what I noticed was that the flow of the Evans through this hose was
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, but it=
|
[quote][b]
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frans(at)privatepilots.nl
Guest
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| Posted: Sun Feb 26, 2012 1:39 pm Post subject: Laminova heat exchanger and Evans coolant |
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On 02/26/2012 08:44 PM, Bud Yerly wrote:
| Quote: | Just my opinion...I'm a 50/50 guy for now.
|
In most cases 50/50 is the best solution. I wanted to try Evans because
I have cooling overcapacity so the reduced heat transfer is no issue,
and the idea of running at zero pressure is interesting in terms of
safety. Furthermore the engine can safely be operated at a higher
temperature, which is good for performance. (This is not so obvious, but
think about it this way: we ignite the fuel to get heat. Heat is what
drives our engines. All heat taken away from the engine is a loss of
energy. We should not cool any more than necessary to keep the engine
from melting.)
But now it appears the viscosity is a problem, so I'm back at 50/50.
Oh BTW I misunderstood your previous post, thought you were saying that
with Evans you had cooler CHT's but I now understand you weren't saying
that.
| Quote: | > > I have used the Evans in a stock trigear and have found my CHTs were
> > about 15 degrees cooler with the glycol.
|
If you ever consider using Evans again, forget about their prep fluid.
Evans is a mixture of polypropylene glycol and ethylene glycol. Regular
anti-freeze is pure ethylene glycol. So you can prep your engine by
pouring pure anti-freeze in it, and then drain it again with any water
that was remaining. If some droplets of anti-freeze remain it doesn't
matter as it is just one of the components of Evans itself.
And if you have water in your Evans you don't have to throw it away but
you can just boil the water out on a stove. Or even in your engine if
you leave the cap off.
Frans
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budyerly(at)msn.com
Guest
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| Posted: Tue Feb 28, 2012 8:14 am Post subject: Laminova heat exchanger and Evans coolant |
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|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> I boil it out as you say.
Hope the heat exchanger works out.
Bud
[quote] ---
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Gilles.Thesee(at)ac-greno
Guest
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| Posted: Sat Mar 03, 2012 3:41 pm Post subject: Laminova heat exchanger and Evans coolant |
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Frans Veldman a écrit :
| Quote: | Furthermore the engine can safely be operated at a higher
temperature, which is good for performance. (This is not so obvious, but
think about it this way: we ignite the fuel to get heat. Heat is what
drives our engines. All heat taken away from the engine is a loss of
energy. We should not cool any more than necessary to keep the engine
from melting.)
|
Frans and all,
Please pardon me for jumping in. I would like to point out that running
an engine hotter implies *greater* heat rejection, all other things
being equal, since heat rejection is a direct funtion of the the
temperature difference between metal and coolant.
Also in a liquid cooled engine, some degree of local boiling (nucleate
boiling) *does* occur. It is this local boiling that insures protection
from hot spot, due to boiling removing enormously more heat than just
heating liquid. Naturally we are speaking of an adequate flow of coolant
which removes the bubbles and let them collapse in the general flow.
Several thorough NACA reports have been published on the subject
((TN-1498, TN-2049). Some info (mostly in French I'm afraid) at
http://contrails.free.fr/engine_liquide_refroid.php.
Bottom line, no need to be afraid of some internal boiling, and
everybody will agree that 50/50 coolant is better, and water is best
(but it can freeze).
Best regards,
--
Gilles
http://contrails.free.fr
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frans(at)privatepilots.nl
Guest
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| Posted: Sun Mar 04, 2012 2:37 am Post subject: Laminova heat exchanger and Evans coolant |
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|
On 03/04/2012 12:40 AM, Gilles Thesee wrote:
| Quote: | > Furthermore the engine can safely be operated at a higher
> temperature, which is good for performance.
|
| Quote: | Please pardon me for jumping in. I would like to point out that running
an engine hotter implies *greater* heat rejection, all other things
being equal, since heat rejection is a direct funtion of the the
temperature difference between metal and coolant.
|
This temperature difference would remain constant. If I close the cowl
flap to raise the temperature, I'm raising the temperature of the
coolant. Since the temp difference between the coolant and cylinder head
is constant, CHT will follow, and this will cause a higher efficiency.
Furthermore, it is best to keep the engine at the same temperature all
the time. All metal parts expand with a different rate, so if you keep
the engine at one temperature, all parts will "run in" for that
temperature wich will give the best fitting, i.e. least friction and
abrasion, while at the same time keeping the tightest fit so compression
will not suffer.
Keeping the engine always at the same temperature will in reality imply
that you keep the engine temperature close to the upper limit. In cars
we use water thermostats for this, but in the Europa we have to do this
manually, i.e. by using a cowl flap. (Or use a water thermostat which
keeps you dragging air through a radiator without any good reason,
spoiling our good attempts to keep the drag of the airplane as low as
possible).
| Quote: | Also in a liquid cooled engine, some degree of local boiling (nucleate
boiling) *does* occur. It is this local boiling that insures protection
from hot spot, due to boiling removing enormously more heat than just
heating liquid. Naturally we are speaking of an adequate flow of coolant
which removes the bubbles and let them collapse in the general flow.
|
I largely agree with you here. If localized boiling would be a problem,
the engine would destroy itself pretty fast. This doesn't generaly
happen, so the problem doesn't exist. That said, your 'adequate flow of
coolant' is often less at places where nucleate boiling occurs, this
sub-optimal flow is often the cause of mucleate boiling. In a cylinder
head, it is difficult to keep the coolant flowing at the same rate at
all possible locations.
(BTW I wonder whether the "5 minute restriction" of the Rotax 914 has
anything to do with nucleate boiling)
The main reason I like the Evans coolant is that it operates at zero
pressure. In a Rotax we are pressurizing our coolant systems at 1.2 bar,
which is quite a lot. The tiniest leak will cause you to loose your
coolant pretty quick, and there is always a risk that a loose hose will
blow off. Of course, proper maintenance will take away most of the risk,
but not all of it.
Furthermore if something bad happens which causes your engine to
overheat, let's say to 140 degrees C, the 50/50 coolant will boil and
finds its way out, leaving you with no cooling at all. With Evans you
have the option to keep the engine running and get yourself out of a bad
situation before the engine gives up.
So, if everything is equal, I would prefer Evans. But alas it won't flow
properly through my heat exchanger so I'll stick to 50/50.
Frans
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kees de bussy
Joined: 16 Jul 2009
Posts: 18
Location: the netherlands
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| Posted: Mon Mar 05, 2012 3:17 pm Post subject: Re: Laminova heat exchanger and Evans coolant |
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Hi Frans and others,
Maybe a little late but herewith what I experienced with Evans in my trigear XS with 912S and a regular setup. I flew my plane with Evans and was happy with the cooling performance.
Until I got an coolant hose which ruptured just after take-off. The first thing I noticed was a little smoke entering the cockpit followed by a very bad smell (a little like burning plastic). So I was thinking at first it was fire. Pulling back the power made the smoke disappear. After landing I noticed the Evans dripping out of the cowling. This happened abroad and during the weekend (of course).
We were lucky that there were a lot of very helpful people around (thank you again for all the help) so the replacement of the hose was not the biggest deal. But it was impossible to get Evans anywhere. So I filled it up with plain water to fly back home.
Flying home I noticed that the engine (oil and water) was running approx. 10 degr. C cooler (less then 80 degr C in level flight) and that the temperature of the water was fluctuating significant more. (from a climb to level flight or with different powersettings).
So from the cooling performance side I preferred the Evans, but from the practical side I preferred glycol/water mix. From the safety side I preferred glycol/water, I know now how bad Evans smells when it leaks on your exhaust and what kind of smoke it generates. I have not done research on this subject but it cannot be healthy (at least I think). I realize that glycol/water smells an smokes too, but not so bad as Evans.
I use now a water/glycol mix with a max. temperature limit of 150 deg. C but I still have to make a cowl flap to control my temperatures. (at lower temperatures I use tape to make my cooling air intake approx. 75% smaller and run still at pretty low temps. The only times that (mainly water)temperatures go up pretty much is in warm weather and long or slow climbs.
Regards,
Kees de Bussy
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