Today's Message Index:
----------------------
1. 07:05 AM - Temps (BobbyPaulk@comcast.net)
2. 08:08 AM - Re: low compression on Jabiru engine using AVGAS (Kayberg@aol.com)
3. 08:35 AM - Re: Temps (Mark Hubelbank)
4. 08:48 AM - Re: low compression on Jabiru engine using AVGAS (BobsV35B@aol.com)
5. 10:25 AM - Re: Temps (Marvin Williams)
6. 10:57 AM - Re: Temps (Mark Hubelbank)
7. 11:25 AM - Re: Temps (Marvin Williams)
8. 12:36 PM - Re: Temps (BobsV35B@aol.com)
9. 01:55 PM - Re: Temps (Mark Hubelbank)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
List,
I am reading all kinds of info on what is supposed to be but where is the info
on what is the proper jetting. I am particularly interested in a Jabiru 3300 (
with Hydraulic lifters ) on a Zodiac 601 XL. I am running a 260 Main Jet and
290 Needle Jet. It still appears I am running too lean. The EGT's go way up at
2500 ~ 2600 RPM and the 100 LL is burning very light gray. Is anyone running
larger jetting. How about a different needle??
I also heard of some changes in the intake manifold although I can not confirm
what has been done if anything.
Also would like to know what is an allowable Cylinder Head Temperature. I have
them all below 300 except #6.
It goes up to 335 ~ 340 at some power settings. The lowest I can maintain is about
310.
I have tilted the carb, divided the intake elbow, changed the Ram Air Ducts, added
baffles and I am still baffled : )
One day I would like to just get in the plane and enjoy the ride without having
to be constantly watching what the temps are doing and I would like for my engine
to last to TBO or at least near that.
Please comment on what your set up might be and the temps you are experiencing.
What is acceptable on CHT for long term life of the engine??
Bobby
601 XL B
103 hrs. & still experimenting.
Jacksonville Fl.
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: low compression on Jabiru engine using AVGAS |
Barry,
Do you have significant experience with Jabiru engines? Your comments
would indicate a background in other engines (Ly-Con) which are not the
same as a Jabiru.
For example, the carbs are not leanable, nor is leaning suggested by Jabiru
Further, since the Jab engines have such a low oil volume, your Marvel
Mystery Oil suggestion is not a good one, and might generate a whole other
set of problems.
Doug Koenigsberg
In a message dated 10/20/2010 11:10:11 P.M. Eastern Daylight Time,
flyadive@gmail.com writes:
Christian:
There is a VERY good chance you are experiencing the same problems MANY
engines here in the USA are experiencing while running on 100LL. 100LL is
really not Low Lead at all. It is four times the lead as the old AvGas 80.
Since you are having low compression I would bet that they are
experiencing lead/coke build up in the valve stems.
If the build up goes untreated the valve will stick in the down (open)
position and if the valve - cylinder clearance is an interference fit they
will be spitting out valve parts. AND even if it is not an interference fit,
the compression will go to zero and still again they will be looking for an
emergency field and new engine parts.
The options are:
Use TCP in the fuel to reduce lead build up
LEAN AGGRESSIVELY - ALL THE TIMES -- Even when taxing.
Use AUTO - MoGas or a mixture of MoGas & AvGas. Just keep the octane
where needed.
1 hour flight before every oil change put in one quart of MMO (Marvell
Mystery Oil) - This helps clean the build up.
Now, these suggestion come with the limited information you gave. We don't
know how the engines are being run.
The time between oil changes.
The type of oil being used.
The quality of the gas and at least a dozen more items.
Since you identified that the engines have low compression - Have you
identified where they are leaking from?
Valves or Rings?
Any gasket leaks?
Fill in the blanks on the above questions and I'll try to diagnose.
GOOD LUCK,
Barry
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Bobby,
Others may have this working but I never got a Bing to work in the
CH601 airframe. The right angle bend of the airflow was just too much
for it. I now have a TBI-40-3 (not S) mounted horizontally with a 2 inch
spacer from the engine and so far it is an order of magnitude
improvement. Of course, one can now set the mixture. I run it rich
(EGT's around 1250 or below at high/full throttle) then lean it as soon
as throttle is reduced. I have been posting pictures of this at
photo.hubbles.com.
On 10/22/2010 10:02 AM, BobbyPaulk@comcast.net wrote:
> List,
> I am reading all kinds of info on what is supposed to be but where is
> the info on what is the proper jetting. I am particularly interested
> in a Jabiru 3300 ( with Hydraulic lifters ) on a Zodiac 601 XL. I am
> running a 260 Main Jet and 290 Needle Jet. It still appears I am
> running too lean. The EGT's go way up at 2500 ~ 2600 RPM and the 100
> LL is burning very light gray. Is anyone running larger jetting. How
> about a different needle??
> I also heard of some changes in the intake manifold although I can not
> confirm what has been done if anything.
> Also would like to know what is an allowable Cylinder Head
> Temperature. I have them all below 300 except #6.
> It goes up to 335 ~ 340 at some power settings. The lowest I can
> maintain is about 310.
> I have tilted the carb, divided the intake elbow, changed the Ram Air
> Ducts, added baffles and I am still baffled : )
> One day I would like to just get in the plane and enjoy the ride
> without having to be constantly watching what the temps are doing and
> I would like for my engine to last to TBO or at least near that.
> Please comment on what your set up might be and the temps you are
> experiencing. What is acceptable on CHT for long term life of the engine??
>
> Bobby
> 601 XL B
> 103 hrs. & still experimenting.
> Jacksonville Fl.
> *
>
>
> *
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: low compression on Jabiru engine using AVGAS |
Good Morning Doug,
Your comment is correct as far as it goes.
However, you will note that Jabiru does suggest changing the jets and the
metering rod to get the mixtures desired. The Bing Carburetor does
automatically adjust the mixture due to changes in altitude, but the changes at
high
power and at cruise are made by changing the components in the carburetor
to compensate for different RPM on various engine applications.
Christian's problem still may be heavily associated with the 100/130 fuel
that is being used. 100/130 is NOT the same as 100LL. If the 100/130 AVGAS
still has the composition that we in the USA had before 100LL came on the
scene, he is getting an abominable amount of lead in the engine. If it is
running rich at relatively low power settings (below seventy-five percent or
so) lead will be built up on valve stems, spark plugs, and in the ring
lands. No more lead should be used than is absolutely required for the
compression being used.
Higher octane fuel does no good at all in an engine that does not have a
compression ratio requiring it. Getting a high octane rating by using lots of
lead is especially hard on the engine. The more modern USA standard 100 LL
has a LOT less lead than does/did 100/130 AVGAS.
Not sure which is available where Christian operates, but lead is bad and
should be avoided wherever possible.
While the fuel used at full takeoff power must be rich enough to have a
suitable octane rating to avoid detonation at that power, no lead at all is
needed at cruise power and operating on the lean side of best power for
cruise is always the best for the engine provided that distribution is adequate.
Jabiru attempts to get a suitably rich mixture at takeoff power and a
suitably lean mixture at cruise power by selecting appropriate fuel rods and
suitable jetting. The Bing Carburetor works great when it is suitably set up.
Personally, I would prefer to have manual mixture control, but I am
horribly old fashioned. <G>
Happy Skies,
Old Bob
In a message dated 10/22/2010 10:09:01 A.M. Central Daylight Time,
Kayberg@aol.com writes:
Barry,
Do you have significant experience with Jabiru engines? Your comments
would indicate a background in other engines (Ly-Con) which are not the
same as a Jabiru.
For example, the carbs are not leanable, nor is leaning suggested by Jabiru
Further, since the Jab engines have such a low oil volume, your Marvel
Mystery Oil suggestion is not a good one, and might generate a whole other
set of problems.
Doug Koenigsberg
In a message dated 10/20/2010 11:10:11 P.M. Eastern Daylight Time,
flyadive@gmail.com writes:
Christian:
There is a VERY good chance you are experiencing the same problems MANY
engines here in the USA are experiencing while running on 100LL. 100LL is
really not Low Lead at all. It is four times the lead as the old AvGas 80.
Since you are having low compression I would bet that they are
experiencing lead/coke build up in the valve stems.
If the build up goes untreated the valve will stick in the down (open)
position and if the valve - cylinder clearance is an interference fit they
will be spitting out valve parts. AND even if it is not an interference fit,
the compression will go to zero and still again they will be looking for an
emergency field and new engine parts.
The options are:
Use TCP in the fuel to reduce lead build up
LEAN AGGRESSIVELY - ALL THE TIMES -- Even when taxing.
Use AUTO - MoGas or a mixture of MoGas & AvGas. Just keep the octane
where needed.
1 hour flight before every oil change put in one quart of MMO (Marvell
Mystery Oil) - This helps clean the build up.
Now, these suggestion come with the limited information you gave. We don't
know how the engines are being run.
The time between oil changes.
The type of oil being used.
The quality of the gas and at least a dozen more items.
Since you identified that the engines have low compression - Have you
identified where they are leaking from?
Valves or Rings?
Any gasket leaks?
Fill in the blanks on the above questions and I'll try to diagnose.
GOOD LUCK,
Barry
(http://www.matronics.com/Navigator?JabiruEngine-List)
(http://www.matronics.com/contribution)
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Mark, would you please elaborate on your leaning techniques? Specifically, at
altitude and cruise power, what EGTs do you lean to?
Thanks,
marvin
N250MR
J250... 3300... w/ TBI40
________________________________
From: Mark Hubelbank <mhubel@nemon.com>
Sent: Fri, October 22, 2010 8:32:03 AM
Subject: Re: JabiruEngine-List: Temps
Bobby,
Others may have this working but I never got a Bing to work in the CH601
airframe. The right angle bend of the airflow was just too much for it. I
now have a TBI-40-3 (not S) mounted horizontally with a 2 inch spacer from
the engine and so far it is an order of magnitude improvement. Of course,
one can now set the mixture. I run it rich (EGT's around 1250 or below at
high/full throttle) then lean it as soon as throttle is reduced. I have been
posting pictures of this at photo.hubbles.com.
On 10/22/2010 10:02 AM, BobbyPaulk@comcast.net wrote:
>List,
>I am reading all kinds of info on what is supposed to be but where is
>the info on what is the proper jetting. I am particularly interested
in
>a Jabiru 3300 ( with Hydraulic lifters ) on a Zodiac 601 XL. I am
>running a 260 Main Jet and 290 Needle Jet. It still appears I am running
>too lean. The EGT's go way up at 2500 ~ 2600 RPM and the 100 LL is
>burning very light gray. Is anyone running larger jetting. How about a
>different needle??
>I also heard of some changes in the intake manifold although I can not
>confirm what has been done if anything.
>
>Also would like to know what is an allowable Cylinder Head Temperature.
>I have them all below 300 except #6.
>
>It goes up to 335 ~ 340 at some power settings. The lowest I can
>maintain is about 310.
>I have tilted the carb, divided the intake elbow, changed the Ram Air
>Ducts, added baffles and I am still baffled : )
>One day I would like to just get in the plane and enjoy the ride without
>having to be constantly watching what the temps are doing and I would
>like for my engine to last to TBO or at least near that.
>Please comment on what your set up might be and the temps you are
>experiencing. What is acceptable on CHT for long term life of the
>engine??
>
>Bobby
>601 XL B
>103 hrs. & still experimenting.
>Jacksonville Fl.
>
>
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Marvin,
Typically I reduce throttle to 2800-2900 RPM by the time I get to
1000 feet AGL Then if not staying in the pattern, I will initially lean
until EGT goes up to in the 1300-1350 range. This results in a fuel flow
rate of 6 GPH or a bit less depending on chosen RPM. Most of the time it
is more like 5.5-5.7 GPH. In theory 6 GPH is 75% power. I have just
started working on lean of peak settings so I don't have much to say
yet. So far it seems to come in at 5 or a bit under 5 GPH.
If the wind ever lets up here, I will get a better set of numbers.
It has been a bit hard to hold a constant airspeed in the past few weeks.
On 10/22/2010 1:18 PM, Marvin Williams wrote:
> Mark, would you please elaborate on your leaning techniques?
> Specifically, at altitude and cruise power, what EGTs do you lean to?
>
> Thanks,
>
> marvin
> N250MR
> J250... 3300... w/ TBI40
>
> ------------------------------------------------------------------------
> *From:* Mark Hubelbank <mhubel@nemon.com>
> *To:* jabiruengine-list@matronics.com
> *Sent:* Fri, October 22, 2010 8:32:03 AM
> *Subject:* Re: JabiruEngine-List: Temps
>
> Bobby,
> Others may have this working but I never got a Bing to work in the
> CH601 airframe. The right angle bend of the airflow was just too much
> for it. I now have a TBI-40-3 (not S) mounted horizontally with a 2
> inch spacer from the engine and so far it is an order of magnitude
> improvement. Of course, one can now set the mixture. I run it rich
> (EGT's around 1250 or below at high/full throttle) then lean it as
> soon as throttle is reduced. I have been posting pictures of this at
> photo.hubbles.com <http://photo.hubbles.com>.
>
> On 10/22/2010 10:02 AM, BobbyPaulk@comcast.net wrote:
>> List,
>> I am reading all kinds of info on what is supposed to be but where is
>> the info on what is the proper jetting. I am particularly interested
>> in a Jabiru 3300 ( with Hydraulic lifters ) on a Zodiac 601 XL. I am
>> running a 260 Main Jet and 290 Needle Jet. It still appears I am
>> running too lean. The EGT's go way up at 2500 ~ 2600 RPM and the 100
>> LL is burning very light gray. Is anyone running larger jetting. How
>> about a different needle??
>> I also heard of some changes in the intake manifold although I can
>> not confirm what has been done if anything.
>> Also would like to know what is an allowable Cylinder Head
>> Temperature. I have them all below 300 except #6.
>> It goes up to 335 ~ 340 at some power settings. The lowest I can
>> maintain is about 310.
>> I have tilted the carb, divided the intake elbow, changed the Ram Air
>> Ducts, added baffles and I am still baffled : )
>> One day I would like to just get in the plane and enjoy the ride
>> without having to be constantly watching what the temps are doing and
>> I would like for my engine to last to TBO or at least near that.
>> Please comment on what your set up might be and the temps you are
>> experiencing. What is acceptable on CHT for long term life of the
>> engine??
>>
>> Bobby
>> 601 XL B
>> 103 hrs. & still experimenting.
>> Jacksonville Fl.
>> *
>>
>>
>> *
>
> --
> Mark Hubelbank
> NorthEast Monitoring
> 2 Clock Tower Place
> Suite 555
> Maynard, MA, 01754 - USA
> mhubel@nemon.com
> 978-443-3955
> *
>
>
> *
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Thanks Mark,
I fully understand the difficulty in holding steady RPMs in turbulence!
Experience the same myself.
I am really interested in seeing your EGT spread at altitude and cruise power
when you get a chance to establish that data.
FWIW, I lean our TBI to 1382 deg F on the hottest cylinder and then live with
whatever the others are. EGT spread at altitude is typically around 90 deg F.
I'll be looking for any farther info you post.
Marvin
________________________________
From: Mark Hubelbank <mhubel@nemon.com>
Sent: Fri, October 22, 2010 10:54:36 AM
Subject: Re: JabiruEngine-List: Temps
Marvin,
Typically I reduce throttle to 2800-2900 RPM by the time I get to 1000
feet AGL Then if not staying in the pattern, I will initially lean until EGT
goes up to in the 1300-1350 range. This results in a fuel flow rate of 6 GPH
or a bit less depending on chosen RPM. Most of the time it is more like
5.5-5.7 GPH. In theory 6 GPH is 75% power. I have just started working on
lean of peak settings so I don't have much to say yet. So far it seems to
come in at 5 or a bit under 5 GPH.
If the wind ever lets up here, I will get a better set of numbers. It
has been a bit hard to hold a constant airspeed in the past few weeks.
On 10/22/2010 1:18 PM, Marvin Williams wrote:
Mark, would you please elaborate on your leaning techniques?
Specifically, at altitude and cruise power, what EGTs do you lean to?
>
>Thanks,
>
>marvin
>N250MR
>J250... 3300... w/ TBI40
>
>
________________________________
From: Mark Hubelbank <mhubel@nemon.com>
>To: jabiruengine-list@matronics.com
>Sent: Fri, October 22, 2010 8:32:03 AM
>Subject: Re: JabiruEngine-List: Temps
>
>Bobby,
> Others may have this working but I never got a Bing to work in
>the CH601 airframe. The right angle bend of the airflow was just too
>much for it. I now have a TBI-40-3 (not S) mounted horizontally with
>a 2 inch spacer from the engine and so far it is an order of
>magnitude improvement. Of course, one can now set the mixture. I run
>it rich (EGT's around 1250 or below at high/full throttle) then lean
>it as soon as throttle is reduced. I have been posting pictures of
>this at photo.hubbles.com.
>
>On 10/22/2010 10:02 AM, BobbyPaulk@comcast.net wrote:
>
>>List,
>>I am reading all kinds of info on what is supposed to be but
>>where is the info on what is the proper jetting. I am
>>particularly interested in a Jabiru 3300 ( with Hydraulic
>>lifters ) on a Zodiac 601 XL. I am running a 260 Main Jet and
>>290 Needle Jet. It still appears I am running too lean. The
>>EGT's go way up at 2500 ~ 2600 RPM and the 100 LL is burning
>>very light gray. Is anyone running larger jetting. How about
a
>>different needle??
>>I also heard of some changes in the intake manifold although
I
>>can not confirm what has been done if anything.
>>
>>Also would like to know what is an allowable Cylinder Head
>>Temperature. I have them all below 300 except #6.
>>
>>It goes up to 335 ~ 340 at some power settings. The lowest I
can
>>maintain is about 310.
>>I have tilted the carb, divided the intake elbow, changed the
>>Ram Air Ducts, added baffles and I am still baffled : )
>>One day I would like to just get in the plane and enjoy the ride
>>without having to be constantly watching what the temps are
>>doing and I would like for my engine to last to TBO or at least
>>near that.
>>Please comment on what your set up might be and the temps you
>>are experiencing. What is acceptable on CHT for long term life
>>of the engine??
>>
>>Bobby
>>601 XL B
>>103 hrs. & still experimenting.
>>Jacksonville Fl.
>>
>>
>>
>>
>>
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
>
>
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Good Afternoon Mark,
May I suggest that you try leaning at cruising speeds by first finding the
peak EGT on each of the cylinders. Check the fuel flow when at each peak.
The fuel flow should have a spread of no more than a couple of tenths of a
gallon from the first to peak to the last to peak. That is checking the
general distribution pattern.
(Just as a note, the actual temperature is immaterial! It is the point
where it reaches peak that we are interested in.)
Once you have fairly well balanced distribution, lean for about thirty
degrees on the lean side of peak EGT. That is, if the peak EGT occurs at 1400
EGT, continue leaning until the EGT is at 1370. That will be very close to
the best BSFC or the most power you can get out of each pound of fuel.
Leaner loses efficiency and richer loses efficiency. If what you need is more
power such as when you are climbing higher than ten or twelve thousand feet,
lean to find peak EGT, then richen about fifty or sixty degrees rich of
peak. That will get you the most power you can get for the amount of air being
pumped.
You don't want to lean that way above about seventy-five percent power. It
is the hottest place to operate your engine! Acceptable, even desirable, at
seventy-five percent power or less. Not good at the higher power settings.
Personally I don't lean that way until I can no longer get much above
sixty-five percent power. If you want to use more than seventy-five per cent
power, you need to run at least 150, preferably 250 degrees F above peak EGT.
At those higher power settings, we need the extra fuel to slow the burning
rate so that we can avoid detonation.
Any help at all?
Happy Skies,
Old Bob
In a message dated 10/22/2010 12:57:21 P.M. Central Daylight Time,
mhubel@nemon.com writes:
Marvin,
Typically I reduce throttle to 2800-2900 RPM by the time I get to 1000
feet AGL Then if not staying in the pattern, I will initially lean until EGT
goes up to in the 1300-1350 range. This results in a fuel flow rate of 6 GPH
or a bit less depending on chosen RPM. Most of the time it is more like
5.5-5.7 GPH. In theory 6 GPH is 75% power. I have just started working on
lean of peak settings so I don't have much to say yet. So far it seems to come
in at 5 or a bit under 5 GPH.
If the wind ever lets up here, I will get a better set of numbers. It has
been a bit hard to hold a constant airspeed in the past few weeks.
On 10/22/2010 1:18 PM, Marvin Williams wrote:
Mark, would you please elaborate on your leaning techniques?
Specifically, at altitude and cruise power, what EGTs do you lean to?
Thanks,
marvin
N250MR
J250... 3300... w/ TBI40
____________________________________
From: Mark Hubelbank _<mhubel@nemon.com>_ (mailto:mhubel@nemon.com)
(mailto:jabiruengine-list@matronics.com)
Sent: Fri, October 22, 2010 8:32:03 AM
Subject: Re: JabiruEngine-List: Temps
Bobby,
Others may have this working but I never got a Bing to work in the CH601
airframe. The right angle bend of the airflow was just too much for it. I
now have a TBI-40-3 (not S) mounted horizontally with a 2 inch spacer from
the engine and so far it is an order of magnitude improvement. Of course, one
can now set the mixture. I run it rich (EGT's around 1250 or below at
high/full throttle) then lean it as soon as throttle is reduced. I have been
posting pictures of this at _photo.hubbles.com_ (http://photo.hubbles.com/) .
On 10/22/2010 10:02 AM, _BobbyPaulk@comcast.net_
(mailto:BobbyPaulk@comcast.net) wrote:
List,
I am reading all kinds of info on what is supposed to be but where is the
info on what is the proper jetting. I am particularly interested in a
Jabiru 3300 ( with Hydraulic lifters ) on a Zodiac 601 XL. I am running a 260
Main Jet and 290 Needle Jet. It still appears I am running too lean. The
EGT's go way up at 2500 ~ 2600 RPM and the 100 LL is burning very light gray.
Is anyone running larger jetting. How about a different needle??
I also heard of some changes in the intake manifold although I can not
confirm what has been done if anything.
Also would like to know what is an allowable Cylinder Head Temperature. I
have them all below 300 except #6.
It goes up to 335 ~ 340 at some power settings. The lowest I can maintain
is about 310.
I have tilted the carb, divided the intake elbow, changed the Ram Air
Ducts, added baffles and I am still baffled : )
One day I would like to just get in the plane and enjoy the ride without
having to be constantly watching what the temps are doing and I would like
for my engine to last to TBO or at least near that.
Please comment on what your set up might be and the temps you are
experiencing. What is acceptable on CHT for long term life of the engine??
Bobby
601 XL B
103 hrs. & still experimenting.
Jacksonville Fl.
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
_mhubel@nemon.com_ (mailto:mhubel@nemon.com)
978-443-3955
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
_mhubel@nemon.com_ (mailto:mhubel@nemon.com)
978-443-3955
(http://www.matronics.com/Navigator?JabiruEngine-List)
(http://www.matronics.com/contribution)
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Bob,
In my previous PA24-260 (Lycoming IO540) I did something close to
what you are describing except I tended to keep it rich above 70% power
instead of 75%. Typically that plane was flown at 65% power.
For the moment, given the temperature recommendations from Jabiru
which are quite different from those from Lycoming or Contental, I am
temporarily sticking to absolute temperatures. Although EGT can be
questionable to measure in an absolute sense, today's instruments are
better and with careful placement of probes there is a little hope.
Mostly these settings are at least as conservative as the difference
from peak method. At least they are with the TBI-40-3 I am using.
Also with the Jabiru, I don't like to have the EGT around peak with
power above 60% even long enough to get good stable values across all
cylinders.
Weather has been getting in the way of a careful lean of peak analysis.
With the Bing, the temperatues were so unstable that any measure
was not meaningful. I think that was due to the very small space
available for the right angle bend in the air intake but I gave up
trying to make the Bing work acceptably.
On 10/22/2010 3:14 PM, BobsV35B@aol.com wrote:
> Good Afternoon Mark,
> May I suggest that you try leaning at cruising speeds by first finding
> the peak EGT on each of the cylinders. Check the fuel flow when at
> each peak. The fuel flow should have a spread of no more than a couple
> of tenths of a gallon from the first to peak to the last to peak. That
> is checking the general distribution pattern.
> (Just as a note, the actual temperature is immaterial! It is the point
> where it reaches peak that we are interested in.)
> Once you have fairly well balanced distribution, lean for about thirty
> degrees on the lean side of peak EGT. That is, if the peak EGT occurs
> at 1400 EGT, continue leaning until the EGT is at 1370. That will be
> very close to the best BSFC or the most power you can get out of each
> pound of fuel. Leaner loses efficiency and richer loses efficiency. If
> what you need is more power such as when you are climbing higher than
> ten or twelve thousand feet, lean to find peak EGT, then richen about
> fifty or sixty degrees rich of peak. That will get you the most power
> you can get for the amount of air being pumped.
> You don't want to lean that way above about seventy-five percent
> power. It is the hottest place to operate your engine! Acceptable,
> even desirable, at seventy-five percent power or less. Not good at the
> higher power settings.
> Personally I don't lean that way until I can no longer get much above
> sixty-five percent power. If you want to use more than seventy-five
> per cent power, you need to run at least 150, preferably 250 degrees F
> above peak EGT. At those higher power settings, we need the extra fuel
> to slow the burning rate so that we can avoid detonation.
> Any help at all?
> Happy Skies,
> Old Bob
> In a message dated 10/22/2010 12:57:21 P.M. Central Daylight Time,
> mhubel@nemon.com writes:
>
> Marvin,
> Typically I reduce throttle to 2800-2900 RPM by the time I get
> to 1000 feet AGL Then if not staying in the pattern, I will
> initially lean until EGT goes up to in the 1300-1350 range. This
> results in a fuel flow rate of 6 GPH or a bit less depending on
> chosen RPM. Most of the time it is more like 5.5-5.7 GPH. In
> theory 6 GPH is 75% power. I have just started working on lean of
> peak settings so I don't have much to say yet. So far it seems to
> come in at 5 or a bit under 5 GPH.
> If the wind ever lets up here, I will get a better set of
> numbers. It has been a bit hard to hold a constant airspeed in the
> past few weeks.
>
> On 10/22/2010 1:18 PM, Marvin Williams wrote:
>> Mark, would you please elaborate on your leaning techniques?
>> Specifically, at altitude and cruise power, what EGTs do you lean to?
>>
>> Thanks,
>>
>> marvin
>> N250MR
>> J250... 3300... w/ TBI40
>>
>> ------------------------------------------------------------------------
>> *From:* Mark Hubelbank <mhubel@nemon.com>
>> *To:* jabiruengine-list@matronics.com
>> *Sent:* Fri, October 22, 2010 8:32:03 AM
>> *Subject:* Re: JabiruEngine-List: Temps
>>
>> Bobby,
>> Others may have this working but I never got a Bing to work
>> in the CH601 airframe. The right angle bend of the airflow was
>> just too much for it. I now have a TBI-40-3 (not S) mounted
>> horizontally with a 2 inch spacer from the engine and so far it
>> is an order of magnitude improvement. Of course, one can now set
>> the mixture. I run it rich (EGT's around 1250 or below at
>> high/full throttle) then lean it as soon as throttle is reduced.
>> I have been posting pictures of this at photo.hubbles.com
>> <http://photo.hubbles.com/>.
>>
>> On 10/22/2010 10:02 AM, BobbyPaulk@comcast.net wrote:
>>> List,
>>> I am reading all kinds of info on what is supposed to be but
>>> where is the info on what is the proper jetting. I am
>>> particularly interested in a Jabiru 3300 ( with Hydraulic
>>> lifters ) on a Zodiac 601 XL. I am running a 260 Main Jet and
>>> 290 Needle Jet. It still appears I am running too lean. The
>>> EGT's go way up at 2500 ~ 2600 RPM and the 100 LL is burning
>>> very light gray. Is anyone running larger jetting. How about a
>>> different needle??
>>> I also heard of some changes in the intake manifold although I
>>> can not confirm what has been done if anything.
>>> Also would like to know what is an allowable Cylinder Head
>>> Temperature. I have them all below 300 except #6.
>>> It goes up to 335 ~ 340 at some power settings. The lowest I can
>>> maintain is about 310.
>>> I have tilted the carb, divided the intake elbow, changed the
>>> Ram Air Ducts, added baffles and I am still baffled : )
>>> One day I would like to just get in the plane and enjoy the ride
>>> without having to be constantly watching what the temps are
>>> doing and I would like for my engine to last to TBO or at least
>>> near that.
>>> Please comment on what your set up might be and the temps you
>>> are experiencing. What is acceptable on CHT for long term life
>>> of the engine??
>>>
>>> Bobby
>>> 601 XL B
>>> 103 hrs. & still experimenting.
>>> Jacksonville Fl.
>>> *
>>>
>>>
>>> *
>>
>> --
>> Mark Hubelbank
>> NorthEast Monitoring
>> 2 Clock Tower Place
>> Suite 555
>> Maynard, MA, 01754 - USA
>> mhubel@nemon.com
>> 978-443-3955
>> *
>>
>>
>> *
>
> --
> Mark Hubelbank
> NorthEast Monitoring
> 2 Clock Tower Place
> Suite 555
> Maynard, MA, 01754 - USA
> mhubel@nemon.com
> 978-443-3955
>
> *
>
> ===================================
> List href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.matronics.com/Navigator?JabiruEngine-List
> ===================================
> ms.matronics.com/">http://forums.matronics.com
> ===================================
> tp://www.matronics.com/contribution">http://www.matronics.com/contribution
> ===================================
>
> *
>
> *
>
>
> *
--
Mark Hubelbank
NorthEast Monitoring
2 Clock Tower Place
Suite 555
Maynard, MA, 01754 - USA
mhubel@nemon.com
978-443-3955
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|