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MHerder
Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX
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 Posted: Sat Mar 12, 2011 1:15 pm Post subject: Radiator Hose for Intake and 1,3,5 lean |
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Hey guys,
Scenario:
Jab 3300, wood 64x47 Zodiac 601 HD.
Recently rejetted from a .255 to .250 b/c I was running rich at high end.
Flew it for about 5-10 hrs with the .250 in it, all was good, left bank was a little on the lean side and I was getting about 3100 rpm level at cruise on a good day.
Decided last night to try to remove the scat hose from intake and replace with smooth lined radiator hose 2 1/8" diameter, and nice smooth molded 90 degree bend from airbox.
I had expectations that I would get more power, and more even distribution of fuel, the exact opposite happened. One bank is now running even leaner, and much to my supprise I was lucky to get 2850 rpm today. I'm kind of bummed about this. What gives?
My thoughts are that now that I'm getting more air to the engine, maybe my mixture might actually be too lean. But the reality is I have one rich bank and one low bank with egts ranging from 1080-1150 on 1,3,5 to 13-1350 on 2,4,6. The average of them is about right, but there is a pretty big desparity. As a side note everything is very happy and even at cruise 2200-2500. The measurements I'm giving are MWOT, which is really where I want to dial it in and get the most pwr. It seems what I really need is better and more distribution of the fuel/air I am sending into the manifold, not necissarily more or less fuel.
So I've changed back to the .255 main. I did one high speed taxi like this but it was too windy to fly so I didn't get any good data.
WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose and have to readjust?
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Zodiac 601 HD
Jabiru 3300
Wood Sensinich 64x47
Finally Flying |
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aerobiz1(at)gmail.com
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| Posted: Sat Mar 12, 2011 6:47 pm Post subject: Radiator Hose for Intake and 1,3,5 lean |
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Hi Michael,
Sounds like you have made a pretty poor situation worse, The plenum design on the 3.3 is the cause of a lot of mixture related issues. I know of some that have had some success by simply rotating the carb a few degrees while others have designed and built their own plenum and intake runners.. There is also a mod that removes the flow divider in the plenum and replaces it with a half inch round tube. But you only have to look and see the different inlet runner lengths to see part of the problem. I know that Rotec have designed a plenum and intake runner system that mates to its TBI, that replicates something you would find on a Lycoming.
Obviously your smooth intake mod has upset the flow going into the carb and probably biased the fuel spray pattern to one side. You could try twisting the carb slightly so that the fuel leaving the needle jet is aimed more to the lean bank of cylinders.....
Martin
On Sun, Mar 13, 2011 at 7:15 AM, MHerder <michaelherder(at)beckgroup.com (michaelherder(at)beckgroup.com)> wrote:
[quote] --> JabiruEngine-List message posted by: "MHerder" <michaelherder(at)beckgroup.com (michaelherder(at)beckgroup.com)>
Hey guys,
Scenario:
Jab 3300, wood 64x47 Zodiac 601 HD.
Recently rejetted from a .255 to .250 b/c I was running rich at high end.
Flew it for about 5-10 hrs with the .250 in it, all was good, left bank was a little on the lean side and I was getting about 3100 rpm level at cruise on a good day.
Decided last night to try to remove the scat hose from intake and replace with smooth lined radiator hose 2 1/8" diameter, and nice smooth molded 90 degree bend from airbox.
I had expectations that I would get more power, and more even distribution of fuel, the exact opposite happened. One bank is now running even leaner, and much to my supprise I was lucky to get 2850 rpm today. I'm kind of bummed about this. What gives?
My thoughts are that now that I'm getting more air to the engine, maybe my mixture might actually be too lean. But the reality is I have one rich bank and one low bank with egts ranging from 1080-1150 on 1,3,5 to 13-1350 on 2,4,6. The average of them is about right, but there is a pretty big desparity. As a side note everything is very happy and even at cruise 2200-2500. The measurements I'm giving are MWOT, which is really where I want to dial it in and get the most pwr. It seems what I really need is better and more distribution of the fuel/air I am sending into the manifold, not necissarily more or less fuel.
So I've changed back to the .255 main. I did one high speed taxi like this but it was too windy to fly so I didn't get any good data.
WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose and have to readjust?
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=333642#333642
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http://forums.matronics.com
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le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
[b]
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Sat Mar 12, 2011 7:22 pm Post subject: Radiator Hose for Intake and 1,3,5 lean |
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Michael-
First off, if 1,3, and 5 are 1080-1150, that's NOT lean, that's rich.
The 2,4, and 6 at 13-1350 is on the lean side....unless it is late,
and my brain is fried.
To further explain what Martin is saying...imagine that the spray of
fuel leaving the carb is positioned at the 6 o'clock position inside
the carb (it is, actually). If the lean bank is 2,4, and 6, you need
to rotate the carb bottom so that the 6 o'clock moves toward the
2,4,6 bank of cylinders....this would be toward the 7 o'clock
position in your 601/ tractor installation. This rotation will make
the fuel discharge go on the left side of the flow divider, richening
the left bank of cylinders...the 2,4,6 side. When I was running a
Bing, I made a small pointer that I affixed near the carb and then
made a scratch on the carb so I would have a starting point and could
always return there if I needed to. Be aware that it doesn't take
much of a twist of the carb to make a big difference.
Further, is that 90 degree bend a vertical bend? According to the
wisdom (?) of about 5 years ago, the Bing likes to get its air from
above or below the carb and not coming in from the side. If your new
smooth hose comes to the carb from the side, that alone might have
caused the problem you are now having.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 35mm)
Status: flying...1086 hrs (since 3-27-2006)
On Mar 12, 2011, at 9:43 PM, Martin Hone wrote:
| Quote: | Hi Michael,
Sounds like you have made a pretty poor situation worse, The
plenum design on the 3.3 is the cause of a lot of mixture related
issues. I know of some that have had some success by simply
rotating the carb a few degrees while others have designed and
built their own plenum and intake runners.. There is also a mod
that removes the flow divider in the plenum and replaces it with a
half inch round tube. But you only have to look and see the
different inlet runner lengths to see part of the problem. I know
that Rotec have designed a plenum and intake runner system that
mates to its TBI, that replicates something you would find on a
Lycoming.
Obviously your smooth intake mod has upset the flow going into the
carb and probably biased the fuel spray pattern to one side. You
could try twisting the carb slightly so that the fuel leaving the
needle jet is aimed more to the lean bank of cylinders.....
Martin
On Sun, Mar 13, 2011 at 7:15 AM, MHerder
<michaelherder(at)beckgroup.com> wrote:
<michaelherder(at)beckgroup.com>
Hey guys,
Scenario:
Jab 3300, wood 64x47 Zodiac 601 HD.
Recently rejetted from a .255 to .250 b/c I was running rich at
high end.
Flew it for about 5-10 hrs with the .250 in it, all was good, left
bank was a little on the lean side and I was getting about 3100 rpm
level at cruise on a good day.
Decided last night to try to remove the scat hose from intake and
replace with smooth lined radiator hose 2 1/8" diameter, and nice
smooth molded 90 degree bend from airbox.
I had expectations that I would get more power, and more even
distribution of fuel, the exact opposite happened. One bank is now
running even leaner, and much to my supprise I was lucky to get
2850 rpm today. I'm kind of bummed about this. What gives?
My thoughts are that now that I'm getting more air to the engine,
maybe my mixture might actually be too lean. But the reality is I
have one rich bank and one low bank with egts ranging from
1080-1150 on 1,3,5 to 13-1350 on 2,4,6. The average of them is
about right, but there is a pretty big desparity. As a side note
everything is very happy and even at cruise 2200-2500. The
measurements I'm giving are MWOT, which is really where I want to
dial it in and get the most pwr. It seems what I really need is
better and more distribution of the fuel/air I am sending into the
manifold, not necissarily more or less fuel.
So I've changed back to the .255 main. I did one high speed taxi
like this but it was too windy to fly so I didn't get any good data.
WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose
and have to readjust?
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=333642#333642
===========
-List" target="_blank">http://www.matronics.com/Navigator?
JabiruEngine-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
www.matronics.com/contribution _-
============================================================
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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ple190
Joined: 03 Sep 2010
Posts: 23
Location: Australia
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| Posted: Sat Mar 12, 2011 9:53 pm Post subject: Re: Radiator Hose for Intake and 1,3,5 lean |
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Have you tried a cross insert in the airbox outlet pipe, this has helped a lot of people even out their EGT's. Just epoxy in some .5mm Al or use thin glass
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MHerder
Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX
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| Posted: Sun Mar 13, 2011 8:30 am Post subject: Re: Radiator Hose for Intake and 1,3,5 lean |
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Lynn you're correct I misentered it. 1,3,5 are the hot ones are cooler. My bad.
6 is very cool. At some settings 200-250 degress cooler than the leanest. Which makes sense since it's the first intake closest to the carb. I'm going to try the tilt thing today I'm supprised to hear you say that the tilt makes such a big difference but I'll take your word for it and try about 10-15 degrees bottom of bowl toward 1,3,5.
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
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_________________
Zodiac 601 HD
Jabiru 3300
Wood Sensinich 64x47
Finally Flying |
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flyadive(at)gmail.com
Guest
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| Posted: Sun Mar 13, 2011 9:12 am Post subject: Radiator Hose for Intake and 1,3,5 lean |
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Mike:
I have a real crazy for you. SMOOTH is not always better.
Many years back I changed the intake for a race car from the old wire type ducting to a smooth tube. EXACTLY as you just did. I lost HP.
WHY you ask?
Because the ripples in the old tube caused all sorts of eddies and that caused the carb to draw EVENLY. The smooth tubing actually forced high speed air down the side of the carb past the center and the atomizer for the fuel.
Results:
Poor airflow
Poor atomisation of the fuel.
Poor distribution.
All the same results you have seen.
To prove or disprove this just replace the smooth with the old and see what happens.
Bottom line: Don't over engineer something and become fixated on what you theorize should happen. Just analyze what does happen.
Barry
On Sat, Mar 12, 2011 at 4:15 PM, MHerder <michaelherder(at)beckgroup.com (michaelherder(at)beckgroup.com)> wrote:
[quote]--> JabiruEngine-List message posted by: "MHerder" <michaelherder(at)beckgroup.com (michaelherder(at)beckgroup.com)>
Hey guys,
Scenario:
Jab 3300, wood 64x47 Zodiac 601 HD.
Recently rejetted from a .255 to .250 b/c I was running rich at high end.
Flew it for about 5-10 hrs with the .250 in it, all was good, left bank was a little on the lean side and I was getting about 3100 rpm level at cruise on a good day.
Decided last night to try to remove the scat hose from intake and replace with smooth lined radiator hose 2 1/8" diameter, and nice smooth molded 90 degree bend from airbox.
I had expectations that I would get more power, and more even distribution of fuel, the exact opposite happened. One bank is now running even leaner, and much to my supprise I was lucky to get 2850 rpm today. I'm kind of bummed about this. What gives?
My thoughts are that now that I'm getting more air to the engine, maybe my mixture might actually be too lean. But the reality is I have one rich bank and one low bank with egts ranging from 1080-1150 on 1,3,5 to 13-1350 on 2,4,6. The average of them is about right, but there is a pretty big desparity. As a side note everything is very happy and even at cruise 2200-2500. The measurements I'm giving are MWOT, which is really where I want to dial it in and get the most pwr. It seems what I really need is better and more distribution of the fuel/air I am sending into the manifold, not necissarily more or less fuel.
So I've changed back to the .255 main. I did one high speed taxi like this but it was too windy to fly so I didn't get any good data.
WHAT ELSE COULD IT BE. Anyone else switch to a smooth intake hose and have to readjust?
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=333642#333642
h as List Un/Subscription,
www.matronics.com/Navigator?JabiruEngine-List" target="_blank">http://www.matronics.com/Navigator?JabiruEngine-List
ronics.com/" target="_blank">http://forums.matronics.com
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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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| Posted: Sun Mar 13, 2011 9:51 am Post subject: Radiator Hose for Intake and 1,3,5 lean |
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Actually, being the closest one to the carb doesn't necessarily make
sense that it will be the coolest. My #1 cylinder is the coolest. I
*think* this is because the air/fuel mixture gets revved up and
doesn't want to take the early exits off the freeway, but when the
freeway ends, it takes an off-ramp into #1...forgive me the
automotive example, but that's how I've got it figured. Bottom line
is we are dealing with a very short manifold with the Jabiru engine
(even my updraft manifold with a plenum has its' quirks), which was
designed with compactness and economy in mind, and not necessarily
good function.
I first learned about rotating the carb on this site...but I'll take
part credit for the explanation of why rotating it works, which I
discovered by probing a little further than the "just do it." : )
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Prince prop (64 x 30, P-tip)
Electroair direct-fire ignition system
Rotec TBI-40 injection (sleeved to 35mm)
Status: flying...1086 hrs (since 3-27-2006)
On Mar 13, 2011, at 12:30 PM, MHerder wrote:
| Quote: |
<michaelherder(at)beckgroup.com>
Lynn you're correct I misentered it. 1,3,5 are the hot ones are
cooler. My bad.
6 is very cool. At some settings 200-250 degress cooler than the
leanest. Which makes sense since it's the first intake closest to
the carb. I'm going to try the tilt thing today I'm supprised to
hear you say that the tilt makes such a big difference but I'll
take your word for it and try about 10-15 degrees bottom of bowl
toward 1,3,5.
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=333741#333741
|
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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DaveG601XL
Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh
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| Posted: Tue Mar 15, 2011 6:44 pm Post subject: Re: Radiator Hose for Intake and 1,3,5 lean |
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The flow divider I put inside the Intakehoses.com rubber hose was the best improvement I found for getting left/right bank mixtures and temperatures closer together. This is an old picture showing an early divider. Instead of using .025 and folding the sides, I am now using a .050 piece of aluminum with beveled sides as to not cut into the hose. Been going strong for almost 170 hours and three years now.
Good luck,
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David Gallagher
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