Today's Message Index:
----------------------
1. 04:15 AM - Re: 912 "cylinder type" (Richard Girard)
2. 05:49 AM - Re: Question about High EGTs on a 912 (Ollie Washburn)
3. 05:49 AM - Re: 912 "cylinder type" (Hugh McKay)
4. 05:50 AM - Re: Question about High EGTs on a 912 (John Cox)
5. 02:29 PM - Re: Question about High EGTs on a 912 (Richard Girard)
6. 03:53 PM - Re: Question about High EGTs on a 912 (jtortho@aol.com)
7. 04:03 PM - Re: Question about High EGTs on a 912 (FLYaDIVE)
8. 04:11 PM - Re: 912 "cylinder type" (Richard Girard)
9. 04:13 PM - Re: Question about High EGTs on a 912 (Ollie Washburn)
10. 07:13 PM - Re: 912 "cylinder type" (Hugh McKay)
11. 07:13 PM - Re: Question about High EGTs on a 912 (FLYaDIVE)
12. 09:47 PM - Re: Question about High EGTs on a 912 (Noel Loveys)
Message 1
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| Subject: | Re: 912 "cylinder type" |
Sounds like they're not used to dealing with the 912. What they probably se
e
is an elevated iron level from the gear box and they're thinking in terms o
f
the iron cylinders of a Lycosaur.
The 912 uses a process that deposits a hard coating (Nikasil) on an aluminu
m
cylinder. I doesn't wear a lot, or shouldn't at least.
Rick Girard
On Wed, Apr 28, 2010 at 11:27 AM, Les Goldner
<lgold@quantum-associates.com>wrote:
> I had my engine oil analyzed by Aviation Laboratories. They came back an
d
> said they can=92t tell if everything is normal until they know what =93cy
linder
> type=94 is in my 912ULS.
>
> I don=92t know what =93cylinder type=94 comes in a 912ULS and didn=92t kn
ow
> different cylinder types were available. Can someone clue me in here?
>
> Thanks,
>
> Les
>
>
> *
>
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===========
> *
>
>
Message 2
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| Subject: | Re: Question about High EGTs on a 912 |
EGT will tell you many things and everyone should read up up on the
telltale signs and yes a failed mag or failed plug will show a high EGT on
all cyls for mag and single cyl for failed plug. Electronics International
used to and probable still does give a lot of information in their manual.
You may be able to get it on line and if so it is worth the read.
On Wed, Apr 28, 2010 at 1:13 PM, FLYaDIVE <flyadive@gmail.com> wrote:
> Hi Scott:
>
> With a dual Mag system you are correct... Both Mags fire at the same time
.
> Or SHOULD!
> If because of timing or poor connection they do not there will probably b
e
> a poor burn in the cylinder and incomplete burnt fuel will be pushed out
the
> exhause pipes.
> The average EGT is between 1300 to 1400 F. So jumping from 1400 to 1600
is
> only a 200 F jump. That is not much - But it is a temp we do not want to
> see.
>
> Cars have experimented with CATALYTIC CONVERTS to burn the incomplete bur
nt
> fuel and they get quite hot. Of course that is also because of the
> catalytic element. And burning fuel in the exhaust system with spark plu
gs
> and nichrome wire have also been tried. All this to reduce out exhaust
> emissions.
>
> Barry
>
>
> On Wed, Apr 28, 2010 at 12:27 PM, Scott DeMeyer <scottsr1100rt@yahoo.com>
wrote:
>
>> Hmm, I don't understand how there could be much, if any unburnt gas in
>> the exhaust pipe while running on one ignition module. It is my
>> understanding that both plugs fire at the same time on a 912. I would th
ink
>> you would need a lot of raw fuel to make EGT increase that much. How cou
ld
>> there be enough unburnt gas to make a difference? I would suspect someth
ing
>> else like a plugged jet or intake vacuum leak.
>>
>> I know I've had many issues with the carb sockets coming apart. This
>> substantially increased my EGT.
>>
>> Scott
>>
>> --- On *Wed, 4/28/10, FLYaDIVE <flyadive@gmail.com>* wrote:
>>
>>
>> From: FLYaDIVE <flyadive@gmail.com>
>>
>> Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
>> To: rotaxengines-list@matronics.com
>> Date: Wednesday, April 28, 2010, 7:23 AM
>>
http://mc/compose?to=flyadive@gmail.com>
>> >
>>
>> Les:
>>
>> Rich hit the nail on the head. Unburnt gas burning in the exhaust
>> pipes will increase your EGT.
>>
>> Prove it to yourself... Fly with ans without a Mag on.
>>
>>
>> Barry
>>
>> On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
>> <lgold@quantum-associates.com<http://mc/compose?to=lgold@quantum-assoc
iates.com>>
>> wrote:
>> > After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 510
0
>> RPM
>> > yesterday I noticed an EGT problem. Toward the end of the flight, with
>> OAT
>> > about 65F at 2000=92, the EGTs started creeping up to 1620F (the maxim
um
>> > allowed temp) on one exhaust and about 1590F on the other. It dropped
>> when I
>> > reduced RPM to 4000 or raised it to 5500RPM.
>> >
>> > When I noticed this, I looked around. After getting my head out of a
>> clouds,
>> > I also noticed the engine was running on a single mag. I am hoping tha
t
>> this
>> > was the cause of the overheating, although I don=92t understand why th
is
>> > should be so.
>> >
>> > It=92s going to be raining here (in N. California) for a few days. Si
nce
>> I
>> > can=92t fly to check out if running on both mags will bring the EGTs d
own,
>> I
>> > was wondering if anyone in Rotax land had an opinion about whether
>> running
>> > on a single mag could causing the high EGTs. If you don=92t think run
ning
>> on
>> > a single mag caused the problem, and you have seen this before, I coul
d
>> use
>> > advice as to how to proceed before tearing the carbs apart.
>> >
>> > When I can fly again, I=92ll report if the mag issue was the culprit h
ere.
>> >
>> > Les
>> >
>> >
>> >
>> >
>>
>> http://www.matronics.com/Navigator?RotaxEngines-List -->
>> http://www.matronics.com/contribution <http://forums.matronics.com/>
>>
>>
>> *
>>
>> ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-L
ist
>> ttp://forums.matronics.com
>> _blank">http://www.matronics.com/contribution
>> *
>>
>>
> *
>
===========
===========
===========
===========
> *
>
>
--
>From Central Florida,
Ollie
Message 3
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| Subject: | Re: 912 "cylinder type" |
Les, I think what they need to know is if the engine cylinder walls are
ordinary steel, ceramic, stainless lined, ect.
For the Rotax Engine 912 series the cylinder is steel.
Hugh McKay
From: Les Goldner
Sent: Wednesday, April 28, 2010 12:27 PM
Subject: RotaxEngines-List: 912 "cylinder type"
I had my engine oil analyzed by Aviation Laboratories. They came back
and said they can't tell if everything is normal until they know what
"cylinder type" is in my 912ULS.
I don't know what "cylinder type" comes in a 912ULS and didn't know
different cylinder types were available. Can someone clue me in here?
Thanks,
Les
Message 4
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| Subject: | Question about High EGTs on a 912 |
Just a contrarian view. LOP which is less fuel equates to higher EGTs till you
are on the backside of the Combustion/EGT curve. Excess gas (including unburned)
reduce the temps hence why so many run ROP to save the exhaust valves and
lower EGTs. I will enjoy your explanation of the opposite conclusion.
John Cox
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
Sent: Wednesday, April 28, 2010 7:23 AM
Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
Les:
Rich hit the nail on the head. Unburnt gas burning in the exhaust
pipes will increase your EGT.
Prove it to yourself... Fly with ans without a Mag on.
Barry
On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
<lgold@quantum-associates.com> wrote:
> After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100 RPM
> yesterday I noticed an EGT problem. Toward the end of the flight, with OAT
> about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
> allowed temp) on one exhaust and about 1590F on the other. It dropped when I
> reduced RPM to 4000 or raised it to 5500RPM.
>
> When I noticed this, I looked around. After getting my head out of a clouds,
> I also noticed the engine was running on a single mag. I am hoping that this
> was the cause of the overheating, although I don't understand why this
> should be so.
>
> It's going to be raining here (in N. California) for a few days. Since I
> can't fly to check out if running on both mags will bring the EGTs down, I
> was wondering if anyone in Rotax land had an opinion about whether running
> on a single mag could causing the high EGTs. If you don't think running on
> a single mag caused the problem, and you have seen this before, I could use
> advice as to how to proceed before tearing the carbs apart.
>
> When I can fly again, I'll report if the mag issue was the culprit here.
>
> Les
>
>
Message 5
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| Subject: | Re: Question about High EGTs on a 912 |
John, Lean of Peak IS the backside of the combustion curve and as you say
EGT cools. EGT is measured anywhere from 1" to 4" from the exhaust port not
at the exhaust valve so while you can cool the valve with excess fuel you
will drive up EGT doing it.
Rick Girard
On Wed, Apr 28, 2010 at 2:14 PM, John Cox <johnwcox@pacificnw.com> wrote:
> johnwcox@pacificnw.com>
>
> Just a contrarian view. LOP which is less fuel equates to higher EGTs till
> you are on the backside of the Combustion/EGT curve. Excess gas (including
> unburned) reduce the temps hence why so many run ROP to save the exhaust
> valves and lower EGTs. I will enjoy your explanation of the opposite
> conclusion.
>
> John Cox
>
> -----Original Message-----
> From: owner-rotaxengines-list-server@matronics.com [mailto:
> owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
> Sent: Wednesday, April 28, 2010 7:23 AM
> To: rotaxengines-list@matronics.com
> Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
>
>
> Les:
>
> Rich hit the nail on the head. Unburnt gas burning in the exhaust
> pipes will increase your EGT.
>
> Prove it to yourself... Fly with ans without a Mag on.
>
>
> Barry
>
> On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
> <lgold@quantum-associates.com> wrote:
> > After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100
> RPM
> > yesterday I noticed an EGT problem. Toward the end of the flight, with
> OAT
> > about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
> > allowed temp) on one exhaust and about 1590F on the other. It dropped
> when I
> > reduced RPM to 4000 or raised it to 5500RPM.
> >
> > When I noticed this, I looked around. After getting my head out of a
> clouds,
> > I also noticed the engine was running on a single mag. I am hoping that
> this
> > was the cause of the overheating, although I don't understand why this
> > should be so.
> >
> > It's going to be raining here (in N. California) for a few days. Since I
> > can't fly to check out if running on both mags will bring the EGTs down,
> I
> > was wondering if anyone in Rotax land had an opinion about whether
> running
> > on a single mag could causing the high EGTs. If you don't think running
> on
> > a single mag caused the problem, and you have seen this before, I could
> use
> > advice as to how to proceed before tearing the carbs apart.
> >
> > When I can fly again, I'll report if the mag issue was the culprit here.
> >
> > Les
> >
> >
> >
> >
>
>
Message 6
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| Subject: | Re: Question about High EGTs on a 912 |
yeah but:
if you lean far enough combustion becomes incomplete, so the gas is still
burning as the exhaust vavle opens, resulting in a second, higher EGT.
I learned of this when running the leaning test per GAMI. I was alarme
d when one cylinder when very high quite rapidly during the lean test.
The engine was still running smooth as the 5 other cylinders ( Cherokee
6 , IO 550, , my certified airplane). The gami rep said there will be
a second peak, sometimes. The sent a new injector and now the peak is
the same for all cylinders.
-----Original Message-----
From: Richard Girard <aslsa.rng@gmail.com>
Sent: Thu, Apr 29, 2010 12:19 pm
Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
John, Lean of Peak IS the backside of the combustion curve and as you say
EGT cools. EGT is measured anywhere from 1" to 4" from the exhaust port
not at the exhaust valve so while you can cool the valve with excess fuel
you will drive up EGT doing it.
Rick Girard
On Wed, Apr 28, 2010 at 2:14 PM, John Cox <johnwcox@pacificnw.com> wrote:
m>
Just a contrarian view. LOP which is less fuel equates to higher EGTs til
l you are on the backside of the Combustion/EGT curve. Excess gas (includ
ing unburned) reduce the temps hence why so many run ROP to save the exhau
st valves and lower EGTs. I will enjoy your explanation of the opposite
conclusion.
John Cox
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengi
nes-list-server@matronics.com] On Behalf Of FLYaDIVE
Sent: Wednesday, April 28, 2010 7:23 AM
Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
Les:
Rich hit the nail on the head. Unburnt gas burning in the exhaust
pipes will increase your EGT.
Prove it to yourself... Fly with ans without a Mag on.
Barry
On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
<lgold@quantum-associates.com> wrote:
> After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100
RPM
> yesterday I noticed an EGT problem. Toward the end of the flight, with
OAT
> about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
> allowed temp) on one exhaust and about 1590F on the other. It dropped wh
en I
> reduced RPM to 4000 or raised it to 5500RPM.
>
> When I noticed this, I looked around. After getting my head out of a clo
uds,
> I also noticed the engine was running on a single mag. I am hoping that
this
> was the cause of the overheating, although I don't understand why this
> should be so.
>
> It's going to be raining here (in N. California) for a few days. Since
I
> can't fly to check out if running on both mags will bring the EGTs down,
I
> was wondering if anyone in Rotax land had an opinion about whether runni
ng
> on a single mag could causing the high EGTs. If you don't think running
on
> a single mag caused the problem, and you have seen this before, I could
use
> advice as to how to proceed before tearing the carbs apart.
>
> When I can fly again, I'll report if the mag issue was the culprit here.
>
> Les
>
>
-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-L
ist
http://forums.matronics.com
le, List Admin.
="_blank">http://www.matronics.com/contribution
========================
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Message 7
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| Subject: | Re: Question about High EGTs on a 912 |
John:
ROP & LOP ...
When I took my Complex Training in a Fuel Injected engine I was taught
to Lean - LOP.
I was also told that LOP is ONLY for FUEL INJECTED engines.
All the planes I fly are corroborated so I have never tried to lean LOP.
How much of a fuel savings is it? I have no idea. But, I would
venture to guess in 100 Hrs a year of flying your saving would be 1/4
a GPH so 100 Hrs = 25 Gal... BUT! How much of that 100 Hrs are you in
cruse?
ROP - Now running ROP is a Carburetor issue. And that is mainly
because when leaning not ALL cylinder have the same fuel air ratio. So
they do not all reach the same point at the same time. You lean until
the engine runs rough and then ritchen a bit... How much is a bit?
That will depend on what YOU feel comfortable with. There is NO real
scientific information to go by. It is after all a fishing
expedition. You drop your line in the water and hope you have the
right hook, line, bait and depth. EGT is ONLY an indication and is
variable with probe location, type of probe, air flow around the
engine and calibration of the unit. Probably a few more that I am
missing.
In the long and short of it... We fly for fun and at the end of a year
or even ten years will $200 mean that much? Especially when compared
to an engine overhaul.
Barry
On Wed, Apr 28, 2010 at 3:14 PM, John Cox <johnwcox@pacificnw.com> wrote:
>
> Just a contrarian view. LOP which is less fuel equates to higher EGTs till you
are on the backside of the Combustion/EGT curve. Excess gas (including unburned)
reduce the temps hence why so many run ROP to save the exhaust valves and
lower EGTs. I will enjoy your explanation of the opposite conclusion.
>
> John Cox
>
> -----Original Message-----
> From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
> Sent: Wednesday, April 28, 2010 7:23 AM
> To: rotaxengines-list@matronics.com
> Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
>
>
> Les:
>
> Rich hit the nail on the head. Unburnt gas burning in the exhaust
> pipes will increase your EGT.
>
> Prove it to yourself... Fly with ans without a Mag on.
>
>
> Barry
>
> On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
> <lgold@quantum-associates.com> wrote:
>> After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100 RPM
>> yesterday I noticed an EGT problem. Toward the end of the flight, with OAT
>> about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
>> allowed temp) on one exhaust and about 1590F on the other. It dropped when I
>> reduced RPM to 4000 or raised it to 5500RPM.
>>
>> When I noticed this, I looked around. After getting my head out of a clouds,
>> I also noticed the engine was running on a single mag. I am hoping that this
>> was the cause of the overheating, although I don't understand why this
>> should be so.
>>
>> It's going to be raining here (in N. California) for a few days. Since I
>> can't fly to check out if running on both mags will bring the EGTs down, I
>> was wondering if anyone in Rotax land had an opinion about whether running
>> on a single mag could causing the high EGTs. If you don't think running on
>> a single mag caused the problem, and you have seen this before, I could use
>> advice as to how to proceed before tearing the carbs apart.
>>
>> When I can fly again, I'll report if the mag issue was the culprit here.
>>
>> Les
>>
>>
>>
>>
>
>
Message 8
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|
| Subject: | Re: 912 "cylinder type" |
Hugh, The cylinders of the 912 are most definitely NOT steel. See the heavy
maintenance manual if you don't believe me.
Rick Girard
On Wed, Apr 28, 2010 at 1:28 PM, Hugh McKay <hgmckay@bellsouth.net> wrote:
> Les, I think what they need to know is if the engine cylinder walls are
> ordinary steel, ceramic, stainless lined, ect.
> For the Rotax Engine 912 series the cylinder is steel.
>
> Hugh McKay
>
> *From:* Les Goldner <lgold@quantum-associates.com>
> *Sent:* Wednesday, April 28, 2010 12:27 PM
> *To:* rotaxengines-list@matronics.com ; rotax@yahoogroups.com
> *Subject:* RotaxEngines-List: 912 "cylinder type"
>
> I had my engine oil analyzed by Aviation Laboratories. They came back an
d
> said they can=92t tell if everything is normal until they know what =93cy
linder
> type=94 is in my 912ULS.
>
> I don=92t know what =93cylinder type=94 comes in a 912ULS and didn=92t kn
ow
> different cylinder types were available. Can someone clue me in here?
>
> Thanks,
>
> Les
>
>
> *
>
> href="http://www.matronics.com/Navigator?RotaxEngines-List">http://www.
matronics.com/Navigator?RotaxEngines-List
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c
*
>
> *
>
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===========
===========
===========
> *
>
>
Message 9
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| Subject: | Re: Question about High EGTs on a 912 |
John, you are talking about two different scenarios, normal cyl and one
with plug not firing.
On Wed, Apr 28, 2010 at 3:14 PM, John Cox <johnwcox@pacificnw.com> wrote:
> johnwcox@pacificnw.com>
>
> Just a contrarian view. LOP which is less fuel equates to higher EGTs till
> you are on the backside of the Combustion/EGT curve. Excess gas (including
> unburned) reduce the temps hence why so many run ROP to save the exhaust
> valves and lower EGTs. I will enjoy your explanation of the opposite
> conclusion.
>
> John Cox
>
> -----Original Message-----
> From: owner-rotaxengines-list-server@matronics.com [mailto:
> owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
> Sent: Wednesday, April 28, 2010 7:23 AM
> To: rotaxengines-list@matronics.com
> Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
>
>
> Les:
>
> Rich hit the nail on the head. Unburnt gas burning in the exhaust
> pipes will increase your EGT.
>
> Prove it to yourself... Fly with ans without a Mag on.
>
>
> Barry
>
> On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
> <lgold@quantum-associates.com> wrote:
> > After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100
> RPM
> > yesterday I noticed an EGT problem. Toward the end of the flight, with
> OAT
> > about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
> > allowed temp) on one exhaust and about 1590F on the other. It dropped
> when I
> > reduced RPM to 4000 or raised it to 5500RPM.
> >
> > When I noticed this, I looked around. After getting my head out of a
> clouds,
> > I also noticed the engine was running on a single mag. I am hoping that
> this
> > was the cause of the overheating, although I don't understand why this
> > should be so.
> >
> > It's going to be raining here (in N. California) for a few days. Since I
> > can't fly to check out if running on both mags will bring the EGTs down,
> I
> > was wondering if anyone in Rotax land had an opinion about whether
> running
> > on a single mag could causing the high EGTs. If you don't think running
> on
> > a single mag caused the problem, and you have seen this before, I could
> use
> > advice as to how to proceed before tearing the carbs apart.
> >
> > When I can fly again, I'll report if the mag issue was the culprit here.
> >
> > Les
> >
> >
> >
> >
>
>
--
>From Central Florida,
Ollie
Message 10
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| Subject: | Re: 912 "cylinder type" |
Rick,
Your right! Stupid me.
Hugh
From: Richard Girard
Sent: Thursday, April 29, 2010 12:11 PM
Subject: Re: RotaxEngines-List: 912 "cylinder type"
Hugh, The cylinders of the 912 are most definitely NOT steel. See the
heavy maintenance manual if you don't believe me.
Rick Girard
On Wed, Apr 28, 2010 at 1:28 PM, Hugh McKay <hgmckay@bellsouth.net>
wrote:
Les, I think what they need to know is if the engine cylinder walls
are ordinary steel, ceramic, stainless lined, ect.
For the Rotax Engine 912 series the cylinder is steel.
Hugh McKay
From: Les Goldner
Sent: Wednesday, April 28, 2010 12:27 PM
To: rotaxengines-list@matronics.com ; rotax@yahoogroups.com
Subject: RotaxEngines-List: 912 "cylinder type"
I had my engine oil analyzed by Aviation Laboratories. They came back
and said they can=92t tell if everything is normal until they know what
=93cylinder type=94 is in my 912ULS.
I don=92t know what =93cylinder type=94 comes in a 912ULS and didn=92t
know different cylinder types were available. Can someone clue me in
here?
Thanks,
Les
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Message 11
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| Subject: | Re: Question about High EGTs on a 912 |
Yea, but!!
What is the point that you are trying to make?
That you had the wrong or bad injector and that cylinder was running
richer than the others?
That is all that was happening. Running too rich on one cylinder.
Lower the amount of fuel in the rich cylinder, so all the cylinders
will peak at OR close to the same time.
As for: "so the gas is still burning as the exhaust valve opens" -
That is always true. The exhaust valve is OPEN way before the burn
time of the fuel has been completed. There is a huge overlap of
ignition and valve opening.
Barry
On Thu, Apr 29, 2010 at 6:33 PM, <jtortho@aol.com> wrote:
>
> yeah but:
>
> if you lean far enough combustion becomes incomplete, so the gas is still
> burning as the exhaust vavle opens, resulting in a second, higher EGT. I
> learned of this when running the leaning test per GAMI. I was alarmed when
> one cylinder when very high quite rapidly during the lean test. The engine
> was still running smooth as the 5 other cylinders ( Cherokee 6 , IO 550, ,
> my certified airplane). The gami rep said there will be a second peak,
> sometimes. The sent a new injector and now the peak is the same for all
> cylinders.
>
>
> -----Original Message-----
> From: Richard Girard <aslsa.rng@gmail.com>
> To: rotaxengines-list@matronics.com
> Sent: Thu, Apr 29, 2010 12:19 pm
> Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
>
> John, Lean of Peak IS the backside of the combustion curve and as you say
> EGT cools. EGT is measured anywhere from 1" to 4" from the exhaust port not
> at the exhaust valve so while you can cool the valve with excess fuel you
> will drive up EGT doing it.
> Rick Girard
>
> On Wed, Apr 28, 2010 at 2:14 PM, John Cox <johnwcox@pacificnw.com> wrote:
>>
>> <johnwcox@pacificnw.com>
>>
>> Just a contrarian view. LOP which is less fuel equates to higher EGTs
>> till you are on the backside of the Combustion/EGT curve. Excess gas
>> (including unburned) reduce the temps hence why so many run ROP to save the
>> exhaust valves and lower EGTs. I will enjoy your explanation of the
>> opposite conclusion.
>>
>> John Cox
>>
>> -----Original Message-----
>> From: owner-rotaxengines-list-server@matronics.com
>> [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
>> Sent: Wednesday, April 28, 2010 7:23 AM
>> To: rotaxengines-list@matronics.com
>> Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
>>
>>
>> Les:
>>
>> Rich hit the nail on the head. Unburnt gas burning in the exhaust
>> pipes will increase your EGT.
>>
>> Prove it to yourself... Fly with ans without a Mag on.
>>
>>
>> Barry
>>
>> On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
>> <lgold@quantum-associates.com> wrote:
>> > After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100
>> > RPM
>> > yesterday I noticed an EGT problem. Toward the end of the flight, with
>> > OAT
>> > about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
>> > allowed temp) on one exhaust and about 1590F on the other. It dropped
>> > when I
>> > reduced RPM to 4000 or raised it to 5500RPM.
>> >
>> > When I noticed this, I looked around. After getting my head out of a
>> > clouds,
>> > I also noticed the engine was running on a single mag. I am hoping that
>> > this
>> > was the cause of the overheating, although I don't understand why this
>> > should be so.
>> >
>> > It's going to be raining here (in N. California) for a few days. Since
>> > I
>> > can't fly to check out if running on both mags will bring the EGTs down,
>> > I
>> > was wondering if anyone in Rotax land had an opinion about whether
>> > running
>> > on a single mag could causing the high EGTs. If you don't think running
>> > on
>> > a single mag caused the problem, and you have seen this before, I could
>> > use
>> > advice as to how to proceed before tearing the carbs apart.
>> >
>> > When I can fly again, I'll report if the mag issue was the culprit here.
>> >
>> > Les
>> >
>> >
>> >
>> >
>>
>>
>>
>>
>>
>>
>>
>> ==========
>> -List"
>> target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
>> ==========
>> http://forums.matronics.com
>> ==========
>> le, List Admin.
>> ="_blank">http://www.matronics.com/contribution
>> ==========
>>
>>
>>
>
>
> ===================================
>
> ator?RotaxEngines-List">http://www.matronics.com/Navigator?RotaxEngines-List
>
> ===================================
>
> ttp://forums.matronics.com
>
> ===================================
>
> ibution">http://www.matronics.com/contribution
>
> ===================================
>
>
Message 12
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| Subject: | Question about High EGTs on a 912 |
Generally both mags should fire at the same time but there are exceptions...
The C-172 used to have offset mag timing, Several Ads were out to change
the timing and then change it back. I'm not sure where it is now and of
course there is the question of impulse coupling where one mag will be
timing retarded below 500 rpm for starting. Usually those engines are
started on one mag then when it starts the second mag is turned on.
When catalytic convertors were first installed on cars some people
mistakenly fuelled up with leaded fuel. The catalytic converters, brand
new, would try harder and harder to burn off the lead deposits. This would
turn the convertors white hot and some melted the frames of their cars.
Shortly afterward an insert was put into the gas filler to not allow a
leaded nozzle to put gas into an unleaded fuel vehicle.
Just a bit of trivia.
Noel
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of FLYaDIVE
Sent: April 28, 2010 2:44 PM
Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
Hi Scott:
With a dual Mag system you are correct... Both Mags fire at the same time.
Or SHOULD!
If because of timing or poor connection they do not there will probably be a
poor burn in the cylinder and incomplete burnt fuel will be pushed out the
exhause pipes.
The average EGT is between 1300 to 1400 F. So jumping from 1400 to 1600 is
only a 200 F jump. That is not much - But it is a temp we do not want to
see.
Cars have experimented with CATALYTIC CONVERTS to burn the incomplete burnt
fuel and they get quite hot. Of course that is also because of the
catalytic element. And burning fuel in the exhaust system with spark plugs
and nichrome wire have also been tried. All this to reduce out exhaust
emissions.
Barry
On Wed, Apr 28, 2010 at 12:27 PM, Scott DeMeyer <scottsr1100rt@yahoo.com>
wrote:
Hmm, I don't understand how there could be much, if any unburnt gas in the
exhaust pipe while running on one ignition module. It is my understanding
that both plugs fire at the same time on a 912. I would think you would need
a lot of raw fuel to make EGT increase that much. How could there be enough
unburnt gas to make a difference? I would suspect something else like a
plugged jet or intake vacuum leak.
I know I've had many issues with the carb sockets coming apart. This
substantially increased my EGT.
Scott
--- On Wed, 4/28/10, FLYaDIVE <flyadive@gmail.com> wrote:
From: FLYaDIVE <flyadive@gmail.com>
Subject: Re: RotaxEngines-List: Question about High EGTs on a 912
<http://mc/compose?to=flyadive@gmail.com> >
Les:
Rich hit the nail on the head. Unburnt gas burning in the exhaust
pipes will increase your EGT.
Prove it to yourself... Fly with ans without a Mag on.
Barry
On Wed, Apr 28, 2010 at 12:51 AM, Les Goldner
<lgold@quantum-associates.com
<http://mc/compose?to=lgold@quantum-associates.com> > wrote:
> After flying my Zenith 701 w/a Rotax 912ULS a few hundred miles at 5100
RPM
> yesterday I noticed an EGT problem. Toward the end of the flight, with OAT
> about 65F at 2000', the EGTs started creeping up to 1620F (the maximum
> allowed temp) on one exhaust and about 1590F on the other. It dropped when
I
> reduced RPM to 4000 or raised it to 5500RPM.
>
> When I noticed this, I looked around. After getting my head out of a
clouds,
> I also noticed the engine was running on a single mag. I am hoping that
this
> was the cause of the overheating, although I don't understand why this
> should be so.
>
> It's going to be raining here (in N. California) for a few days. Since I
> can't fly to check out if running on both mags will bring the EGTs down, I
> was wondering if anyone in Rotax land had an opinion about whether running
> on a single mag could causing the high EGTs. If you don't think running
on
> a single mag caused the problem, and you have seen this before, I could
use
> advice as to how to proceed before tearing the carbs apart.
>
> When I can fly again, I'll report if the mag issue was the culprit here.
>
> Les
>
>
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