Today's Message Index:
----------------------
1. 12:50 AM - Re: Re: Coolant flammability tests (Gilles Thesee)
2. 12:55 AM - Re: Re: Coolant flammability tests (Gilles Thesee)
3. 04:54 AM - Re: Rotax 912 Idle Speed Setting (Thom Riddle)
4. 07:07 AM - Re: Rotax 912 Idle Speed Setting (Roger Lee)
5. 07:15 AM - Re: Coolant flammability tests (Roger Lee)
6. 12:31 PM - Re: Re: Rotax 912 Idle Speed Setting (Silvano Gai)
7. 12:32 PM - Re: Coolant flammability tests (Gilles Thesee)
8. 01:12 PM - Re: Re: Rotax 912 Idle Speed Setting (Steve Crimm)
Message 1
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| Subject: | Re: Coolant flammability tests |
Roger Lee a crit :
>
> Hi Rampil,
>
> No actually I use it because the regualr 50/50 can get into hot spots or poor
circulation areas within the heads and get too hot and vaporize. This causes
a vapor space and causes overheating in or around the head. This softens the metal
and causes leaks and warpping. Regular 50/50 boils around 275F or so, and
Evans boils at 375F. This also helps the engine from puking coolant all over
the ground when you are stuck on the tarmac for a while idling or long taxi's
and poor air movement for cooling. The articles written by several authors say
you should use Evans unless you are having an engine over heating problem. Evans
can make you run about 30F warmer, but if it doesn't over heat, so what. If
I was constantly over heating I might drop back to 50/50. Evans will not leave
deposits in the system or corrode parts because it doesn't have any water.
You should use it unless you are always over heating to drop the temps. 30F, but
you are a head of the game if you do not over heat !
> and you use Evans.
>
>
Roger and all,
You are right, as long as your are not overheating, using pure propylene
glycol like Evan's NPG+ won't harm your engine.
What is surprisingly not well known by magazine editors, is that
nucleate boiling is a normal phenomenon in any liquid cooled piston
engine. It helps reject tremendous amounts of heat from the engine.
Phase change from liquid to vapor absorbs many times more heat than just
raising the coolant temperature another degree, and helps convection.
This was clearly established by NACA researchers on liquid cooling
during the '40s.
See Contrails
http://contrails.free.fr/engine_liquide_refroid.php (only in French at
the moment)
Scroll down to the NACA reports.
Also some gneral info at :
http://www.tpub.com/content/doe/h1012v2/css/h1012v2_62.htm
Please note that we are speaking of nucleate boiling, and not of the
"boiling crisis", which is the transition from nucleate to "film
boiling". It is film boiling which tends to isolate the hot walls from
the coolant. It can happen
So the "no boil" argument put forth by propylene glycol sellers is not
so valid.
Also it is not water that leaves deposits, but wrongly formulated
coolants with no inhibitors.
Even the Evans (no water) contains a corrosion inhibitor.
Best regards,
Gilles
http://contrails.free.fr
Message 2
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| Subject: | Re: Coolant flammability tests |
Roger Lee a crit :
> How are you?
> If I remember right the big issue was Evans coolant?
> We discussed this a while back. Bottom line is how high the temps have to get
to cause it to burn and if it is in any type of fire it is a very limited quanity.
Why worry if there is a fire as you have fuel and oil, all the rubber and
plastic in the engine that is far worse and burns at lower temps. When you really
compare Evans to the other things in the engine compartment that burn it's
just at the bottom of the list and you have much bigger problems to worry about
if there is a fire. Some things look good by themselves or on paper, but
when you include the whole picture it's not worth worrying about. I'm a Fireman
and HazMat Tech. by trade for the last 28 years. I have been to, God only knows
how many car fires and I have been to aircraft fires. Knowing what is in the
general area to burn and at what temps. puts Evans Coolant at the bottom of
my list. The only thing hot enoug in our engine is the exhaust manifold. They
are worried about Evans, I think they should be more !
> worried about fuel. It will lite off at a much lower temp. and it will burn
up to 2000F. All the rubber parts and some plastic will lite off if it falls against
the exhaust manifold. There is a lot more of this stuff to start a fire.
There is very little coolant in your engine. Tell them to test all the other
components in the engine compartment. You may not want to fly then. Human nature
usually only carries things out to a certain point and then we quit looking
past that point. Follow it past the Evans to everything else and then this single
point they make isn't as big. The bottom line is any engine fire reguardless
of the cause can be deadly. Good maint. scheduling and checking your equipment
can go a long way to saving your hide. Don't be cheap is what I tell people
when it coes to parts and maint. . The part may look good on the outside,
but it's waiting to bite you on the backside if you neglect it or don't replace
it.
>
Hi Roger,
What is interesting in Ron's report is, he made experiments.
Of course many engine fluids burn, especially oil and fuel. But Ron and
Wayne's findings help us sorting out the coolant flammability issue by
providing hard facts.
Best regards,
Gilles
http://contrails.free.fr
Message 3
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| Subject: | Re: Rotax 912 Idle Speed Setting |
Hugh,
A few more points, some different from what others have said, based on
personal experience synching carbs on our Allegro w/ 912UL and on a
customer's Diamond Katana w/ 912F, also 80 hp.
1) The idle can be made smooth in the 1400-1500 rpm range.
2) Since the Allegro is such a great glider you will have difficulty
getting the airplane to come down on final with the idle speed set at
1800 rpm.
3) Idle above 1800 rpm CAN make the starting carburetor (what some
erroneously call choke) not function properly or at all.
4) With the balance tube disconnected during the pneumatic synch
process, pay attention only to the vaccuum readings and the idle speed.
The engine will seem rough even when the numbers are perfect but will
smooth out when the balance tube is reconnected. Rotax schools don't
always tell you that. Just make the numbers right and it will be silky
smooth with the balance tube reconnected.
Thom Riddle
Message 4
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| Subject: | Re: Rotax 912 Idle Speed Setting |
Hi Thom,
I mean no malice here, but only to debate some points.
The 80 hp v.s. the 100 hp engines are different. The compression is lower in the
80 hp. You might get away with a little lower rpm? All my training and experience
is with the 100 hp.
My Flight Design CT has a glide of 14:1 and at 1800 rpm landings and losing altitude
are not a problem. Setting your rpm down at 1400-1500 makes the gearbox
take a beating form our higher compression and porp inertia. If the engine feels
rough then it is rough. Both my Rotax instructors said not to run them down
this low. Your engine should run as smooth without the crossover as with if the
carbs are balanced exactlly. The crossover tries to keep equal pressure between
them during all running conditions. I have hooked up my gages with the crossover
connected. The lower the rpm the crossover does the least and they will
stay out of balance just not as far. The higher I ran my rpm the more the crossover
helped. It made them close, but still out of balance some. If you balanced
the carbs well you could fly with out the crossover. After time the carbs
slowly can get out of balance, usually not much, but still out. The crossover
was set up to help combat the out of balance carb and to help under normal conditions
to maintain equality between the two. These are constant pressure carbs
and that's why the crossover is so benifical.
The so called choke only adds more fuel for start up. It does not change anything
else.
The rough running will beat up your tranny. Kind of like smoking, won't get you
today, but the future is bad.
--------
Roger Lee
Tucson, Az.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=111133#111133
Message 5
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| Subject: | Re: Coolant flammability tests |
Hi Gilles,
I agree that when a liquid changes phase from the let's say water or coolant to
vapor it has absorbed more heat, momentarily. The problem with that is we can't
circulate vapor and it can and does leave dead spots in the head. Now we loose
the cooling in that spot. Rotax heads are cooled by the coolant and the cylinders
are air cooled. Get a dead vapor spot in the head and the temp. probe
may or may not pick up the heat problem because the spot is isolated and we don't
usually monitor all 4 head temps. Rotax has pictures to demonstrate this problem.
Engine MFG's. try real hard not to have vapor areas in their engines.
--------
Roger Lee
Tucson, Az.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=111135#111135
Message 6
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| Subject: | Re: Rotax 912 Idle Speed Setting |
I have given up with that tool you show in the picture and bought a
Carbtune 2-col and Toolpouch
http://www.carbtune.com/carbdtls.html.
Much superior.
As a matter of fact I have a brand new tool from Lockwood that I want to
sell ;-)
If you are interested contact me.
-- Silvano
Roger Lee wrote:
>
> Hi Hugh,
>
> Carb sync tool picture
>
> --------
> Roger Lee
> Tucson, Az.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=110993#110993
>
>
> Attachments:
>
> http://forums.matronics.com//files/carb_sync_1501_110.jpg
>
>
>
Message 7
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| Subject: | Re: Coolant flammability tests |
Hi Roger,
Thank you for responding.
> The problem with that is we can't circulate vapor and it can and does leave dead
spots in the head.
Nucleate ebullition does help liquid cooling and is present in the
majority of internal combustion engines when at working temperatures.
It is this phenomenon which provides the near constant temps.
Tiny bubbles are created at every hot spot in the engine, cool the area,
then are entrained in the general coolant flow. As soon as they leave
the hot wall, they collapse, due to the coolant temp being lower than
the overheating spots.
When the coolant flow slows, the proportion of nucleate ebullition
rises, helping cooling in adverse conditions.
> Now we loose the cooling in that spot.
If and when the heat flow through the engine wall exceeds the cooling
capacity of nucleate ebullition, then yes "film cooling" develops and
the heat transfer is impaired.
> Engine MFG's. try real hard not to have vapor areas in their engines.
>
Of course I'm not talking of boiling off the coolant, but things are
more subtle than commonly perceived at first glance. A certain amount of
ebullition really helps keeping temperatures under control.
The provided links to the NACA studies on engine liquid cooling, and on
thermal dissipation will shed some light on the phenomenon (and in much
better English ;-)
Evans also gives a clear explanation on nucleate ebullition.
Best regards,
Gilles
http://contrails.free.fr
Message 8
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| Subject: | Re: Rotax 912 Idle Speed Setting |
David,
I am in Roswell
Steve
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of David
Estapa
Sent: Saturday, May 05, 2007 20:34
Subject: Re: RotaxEngines-List: Re: Rotax 912 Idle Speed Setting
--> <davestapa@juno.com>
Steve, where in Atlanta are you? I live in Woodstock, but plane is based in
Calhoun. This morning we balanced carbs on a Zenith 701 with a 912ULS.
We balanced carbs on my Kitfox Series 5, 912ULS a couple of months ago. I
have the gauages.
C. David Estapa
Woodstock, GA
Kitfox 5, N97DE, 912ULS
Do not archive
On Sat, 5 May 2007 19:01:31 -0400 "Steve Crimm"
<steve.crimm@stephenscott.com> writes:
> <steve.crimm@stephenscott.com>
>
> Is there anyone on the forum in the Atlanta area that can do the idle
> and carb sync?
>
> I am in need of both.
>
> Thanks,
>
> Steve Crimm
>
>
> -----Original Message-----
> From: owner-rotaxengines-list-server@matronics.com
> [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of
> Roger Lee
> Sent: Saturday, May 05, 2007 17:58
> To: rotaxengines-list@matronics.com
> Subject: RotaxEngines-List: Re: Rotax 912 Idle Speed Setting
>
> --> <ssadiver1@yahoo.com>
>
> I don't particularlly like the tube type because you have to keep them
> oriented up and should be verticle and not leaned over. I like the
> dial type like in the picture. These can be any orientation and are
> easy to read.
> These are just gages you can pick up at an auto parts or online. The
> gages depending on how much you want to spend are $19-$30. Mine are
> liquid filled.
> The rest of the gage parts set is something you can pick up for about
> $10-$12 at your local hardware store. You do not need any special
> vacumm gages to do this carb sync. Something easy to use and read is
> the best.
>
> Once you do a carb balance you will find it quite easy from then on.
> Just
> remember that the gage with the highest vacumm is the carb getting the
> least fuel. If you need more rpm adjust the carb with the most vacumm
> which gives it more fuel and the vacumm will reduce (i.e. vacumm is
> 12, adjust the carb to get more fuel and the vacumm goes down let's
> say to 10). If you need to decrease rpm then pick the carb with the
> least vacumm and raise its vacumm number by reducing the amount of
> fuel it gets. These adjustments are done by turning the Bowden cable.
> That's the main throttle cable that comes into the carb when you use
> your throttle. You need to use the idle stop screw and the vacumm
> gages to make sure your idle is set at it's correct rpm and the carbs
> are equal when they are at idle.
>
> This doesn't tell you how to do it, but maybe a little insite as to
> what is going on when you look at the gages or your trying to set the
> idle when the gages are connected.
>
> Again if you have any questions call me anytime.
>
> --------
> Roger Lee
> Tucson, Az.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=111052#111052
>
>
>
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>
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