Today's Message Index:
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1. 09:33 AM - Re: Radiator Hose for Intake and 1,3,5 lean (MHerder)
2. 10:12 AM - Re: Radiator Hose for Intake and 1,3,5 lean (FLYaDIVE)
3. 10:51 AM - Re: Re: Radiator Hose for Intake and 1,3,5 lean (Lynn Matteson)
4. 01:36 PM - Intake Hose (BobbyPaulk@comcast.net)
5. 01:50 PM - Re: Intake Hose (Martin Hone)
6. 02:57 PM - Re: Intake Hose (Lynn Matteson)
7. 07:47 PM - Re: Intake Hose (MHerder)
Message 1
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| Subject: | Re: Radiator Hose for Intake and 1,3,5 lean |
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
Message 2
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| Subject: | Re: Radiator Hose for Intake and 1,3,5 lean |
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@beckgroup.com>wrote:
> michaelherder@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
>
>
Message 3
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| Subject: | Re: Radiator Hose for Intake and 1,3,5 lean |
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:
> <michaelherder@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
>
>
Message 4
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Guys,
I am using a 260 main and 290 needle jet and still just barely on the rich side
at full throttle. When I pull back to 2600 ~ 2650 it will lean out. My front
2 cylinders will run 1350 EGT at cruise while the other 4 are below 1200. I believe
this to be due an inherent design problem. I have tried most all the ideas
I have read and nothing seems to work at all throttle settings. I have to cruise
at 2550 or lower or go above 2850 to maintain cooling. Has anyone toyed
with a needle change. I am using the newer leaner tapered needle and black floats.
PLEASE BE ADVISED OF THE PROBLEM I HAD USING SMOOTH RADIATOR HOSE. WHEN IT WARMS
UP IT BECOMES PLIABLE AND WILL COLLAPSE AT FULL THROTTLE. PLEASE INSTALL VANES
TO PREVENT THIS . My engine quit cold on take off roll just prior to lift off.
Another minute and I would have been in the trees.
Bobby
Jab 3300
601 XL "B"
116 hrs.
Message 5
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Hi Bobby,
Have you checked the actual size of the main jet ? Ours had #255 stamped on
it but measured at 0.25mm so we took it out to 0.260 mm which helped. The
EGT is irrelevant below 75% power in my opinion, but you could try placing a
small washer under the needle clip in order to raise it slightly, hence
richening the mixture.
Martin
On Mon, Mar 14, 2011 at 6:32 AM, <BobbyPaulk@comcast.net> wrote:
> Guys,
> I am using a 260 main and 290 needle jet and still just barely on the rich
> side at full throttle. When I pull back to 2600 ~ 2650 it will lean out. My
> front 2 cylinders will run 1350 EGT at cruise while the other 4 are below
> 1200. I believe this to be due an inherent design problem. I have tried most
> all the ideas I have read and nothing seems to work at all throttle
> settings. I have to cruise at 2550 or lower or go above 2850 to maintain
> cooling. Has anyone toyed with a needle change. I am using the newer leaner
> tapered needle and black floats.
> PLEASE BE ADVISED OF THE PROBLEM I HAD USING SMOOTH RADIATOR HOSE. WHEN IT
> WARMS UP IT BECOMES PLIABLE AND WILL COLLAPSE AT FULL THROTTLE. PLEASE
> INSTALL VANES TO PREVENT THIS . My engine quit cold on take off roll just
> prior to lift off. Another minute and I would have been in the trees.
>
> Bobby
> Jab 3300
> 601 XL "B"
> 116 hrs.
>
> *
>
> *
>
>
Message 6
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"I believe this to be due an inherent design problem."
Yup, you got it, Bobby...it's called a compromise solution, and
that's what Jabiru decided to go with in their intake manifold
design. A thing of beauty, that doesn't work worth a damn, in my
estimation....that's the manifold I'm talking about....the rest of
the engine is also a thing of beauty, and some of it works pretty
well most of the time.
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 4:32 PM, BobbyPaulk@comcast.net wrote:
>
(snip)
> I believe this to be due an inherent design problem. I have tried
> most all the ideas I have read and nothing seems to work at all
> throttle settings.
(snip)
>
>
> Bobby
> Jab 3300
> 601 XL "B"
> 116 hrs.
> ============================================================ _-
> ============================================================ _-
> contribution_-
> ===========================================================
Message 7
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Bobby,
I thank you for sharing your experience with your collapsing tube! I take it there
was no warning, but I'm wondering now if my "warning" could be lower than
anticipated RPM. Did you fly at all before this happened or was it on your first
takeoff roll in this configuration? I've got about 1.5 hrs like this now
without the dividers and with the Radiator hose, but with your comments I wont
push it more without some reconsideration as to how to be sure the hose doesn't
collapse.
I will say however that my hose is very rigid (nearly 1/4" tck), but I could see
your point when warm. I would also figure that once it starts to collapse,
it happens almost instantaneously rather than slowly.
--------
One Rivet at a Time!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=333813#333813
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