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3300A - Full Throttle Roughness
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challgren(at)mac.com
Guest

Posted: Tue Jan 13, 2009 10:04 pm Post subject: 3300A - Full Throttle Roughness

Don:



I believe Jon's DVD "3300 Engine Installation" video may have the answer to your problem.  This was shot by Jon at one of Pete's engine installation seminars.

Pete says on the video that at wide-open-throttle if you are getting too much fuel it would result in cooler EGT's and shaking.  If your EGT's are closer to 1,000F than 1300F it is running cool due to the rich mixture.  He says the solution is a smaller main jet.  He says about two-thirds of the Jabiru engines have had to decrease their jet size.  At another point he says they are shipped with 285's and you should ask for the next lower.  bingcarb .com has a good book on the carb and it helped me with carb problems on our first 3300 on a 601.  Pete also said that they would be carrying the smaller jets but you can also talk to the experts at Bing which I believe is in Kansas.

For information on the 3300 installation I think Jon's DVD is a must have.  Five hours of excellent information.

Stan Challgren

701/3300

Evergreen, CO





On Jan 12, 2009, at 23:03 , Don Honabach wrote:

 	  Quote: 	
		  I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.

 

Interestingly, I have no problem with full throttle roughness on take-off/climb-out.

 

I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.

 

Background info:

 

Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.

 

On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.

 

Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).

 

Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.

 

Thanks!

Don Honabach

Tempe, AZ

 



 	  Quote: 	
		  	


	


 [quote][b]

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Jan 14, 2009 5:47 am Post subject: 3300A - Full Throttle Roughness

I'll have to report on the last inch of travel the next time I fly  

it...I think I do get more power, but just how much I haven't paid  

that much attention to.



I just bought a Northstar F210 fuel flow indicator, which is (I've  

heard) similar to the Navman, but don't have it installed yet.



Regarding the seat removal...the first time I bought a seat,  

directions came with it, but not the last two times. I used a slide- 

hammer style device to pull the seat after first tapping the seat  

body with a 5/16 24 tap...I think the directions called for an 8mm  

tap, to which the 5/16-24 is close. I used the same slide hammer  

device to install it, but substituted a close-fitting smooth mandrel  

to drive it home.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 600.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

New skis done and flying





On Jan 13, 2009, at 11:37 PM, Peter Harris wrote:



[quote] 

 <peterjfharris(at)bigpond.com>



 Lynn I think your 3.7mm seat should be fine with gravity feed. I found

 removal of the 2.25 seat and fitting the 1.5 seat made a very big  

 difference

 to mixture at the higher throttle settings using the mech pump.  

 Remove and

 refit was not easy, I made a screw puller and heated the carb to about

 80degC. The seat is a tight interference fit.

 I am continuing with the fuel injection twin injector throttle  

 body. At this

 stage no additional power but total control of mixture. I think the  

 power

 output is limited by restricted flow through the Jab induction  

 collector,

 but had problems using a tapered plenum due to the effect near WOT  

 when most

 of the charge is delivered to the end into #1 and 2. I may spend  

 some time

 building a bottom feed plenum later.

 I get very little increase in power over the last inch of throttle,  

 do you

 also?

 I am also using a Navman fuel flow indicator and find it one of the  

 most

 useful instruments especially for cross country when you can adjust  

 throttle

 to get the desired fuel flow rate and also read fuel remaining  

 accurate to

 2%.

 Peter



 --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Wed Jan 14, 2009 2:17 pm Post subject: 3300A - Full Throttle Roughness

Lynn my tests were done on the ground in static runs. You could try the

throttle movement test on the ground for comparison.

I think after many hours of ground runs the last test I did with the plenum

proves that resistance in the Jab collector is affecting performance, as

follows:



1.	Breakdown at WOT is caused by an unrestricted rush of fuel to the

end of the plenum to #1 and 2. In use of the tapered plenum there is only

one way to stop spectacular engine breakdown at WOT and that is by fitting a

full width baffle 35mm wide and 30mm from the entry inside the plenum.

2.	The baffle neutralizes the effect of the butterfly so that the last

1" of throttle has no effect. The baffle is acting like a partly closed

butterfly downstream. Without the baffle, throttle increases power up to the

point of breakdown ie there is no dead throttle. 

3.	Similarly the last 1" of throttle into the Jab. collector has no

effect but because of internal losses there is normally no breakdown at WOT,

only #1 and 2 go rich.



My tests were conducted on the ground static. I am using a 55 X 72" prop. on

the Quickie which climbs at 1500FPM and cruises at 170KTS at 2950RPM WOT. 

You can appreciate why I am trying to make sure the engine is doing it's

best. The engine is still very tight when hot. It has done about 50hours.



Peter

--

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Wed Jan 14, 2009 2:23 pm Post subject: 3300A - Full Throttle Roughness

Stan,  

The problem I have with that approach is that the selection of jets and needles is being made to compensate for a leaking float valve needle seat.  

The fuel needle seats are not all going to leak at the same rate.   

It seems to me that this is a poor way to tune an engine. I think the carb should first be assembled to Bing specifications for the application with pump feed.  

Then select jets and needles.  

Peter  

         

  

From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of Stanley Challgren

 Sent: Wednesday, 14 January 2009 3:39 PM

 To: jabiruengine-list(at)matronics.com

 Subject: Re: JabiruEngine-List: 3300A - Full Throttle Roughness  

  

   

Don:    

   

    

I believe Jon's DVD "3300 Engine Installation" video may have the answer to your problem.  This was shot by Jon at one of Pete's engine installation seminars.  

    

   

    

Pete says on the video that at wide-open-throttle if you are getting too much fuel it would result in cooler EGT's and shaking.  If your EGT's are closer to 1,000F than 1300F it is running cool due to the rich mixture.  He says the solution is a smaller main jet.  He says about two-thirds of the Jabiru engines have had to decrease their jet size.  At another point he says they are shipped with 285's and you should ask for the next lower.  bingcarb .com has a good book on the carb and it helped me with carb problems on our first 3300 on a 601.  Pete also said that they would be carrying the smaller jets but you can also talk to the experts at Bing which I believe is in Kansas.  

    

   

    

For information on the 3300 installation I think Jon's DVD is a must have.  Five hours of excellent information.  

    

   

    

Stan Challgren  

    

701/3300  

    

Evergreen, CO  

    

   

    

   

    

On Jan 12, 2009, at 23:03 , Don Honabach wrote:  

      



 

           

I'm having an issue where during cruise flight if I go full throttle either in straight and level or climb, the engine gets rough enough that it feels like it will quit. At this point, I obviously don't want to push the issue so I pull back on the throttle until the roughness goes away.  

    

   

    

Interestingly, I have no problem with full throttle roughness on take-off/climb-out.  

    

   

    

I also did some additional testing today and found that if I ease real slow into full throttle from cruise that I still get the roughness but not as bad and that the RPM will increase up to ~2,9xx and then start to degrade as I continue to add power along with additional roughness.  

    

   

    

Background info:  

    

   

    

Full Throttle Static RPM/Ground Run Up is ~2,800RPM. No issues with roughness.  

    

   

    

On my 601HDS, I have a 3300A with the Sensenich Carbon Prop (64"? 2A0J5R64Z-N) that was purchased from Jabiru USA/Pete K. back in 2006.  

    

   

    

Any help greatly appreciated. I've sent this same question to Jabiru USA and haven't gotten a response yet (sent last Thursday and sent another today asking for status).  

    

   

    

Initially thought it was the SCAT intake hose which I replaced with the rubber 90 degree elbow. Same issue with either intake method.  

    

   

    

Thanks!  

    

Don Honabach  

    

Tempe, AZ  

    

   

  

  

  

   

  

   

  

     [quote]



href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.matronics.com/Navigator?JabiruEngine-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/c

[b]

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Wed Jan 14, 2009 3:59 pm Post subject: 3300A - Full Throttle Roughness

Peter-



Just to be sure I'm understanding your prop, I assume that you are  

listing the diameter (55") first, and the pitch (72") second, as is  

the normal way to describe a propellor, correct? (I've seen props  

described the other way around, and their performance numbers didn't  

add up) That seems like the only way that you could do 170 KTS at  

2950 rpm...to me at least. That must be one very light aircraft to  

climb that well and go that fast. You'll have to forgive me as I know  

nothing about the Quickie. I would have thought that you'd have more  

hours on your engine by now Peter....a lot of research and not much  

flying, eh? : ) Maybe when you have more hours on the engine it will  

loosen up and the effects of the last 1" of throttle travel will change?



I'm a bit confused by your description of the rush of fuel to the end  

of the plenum to #1 and 2. It seems like the fuel must be being drawn  

to those cylinders by vacuum from those cylinders. Do you suppose  

this is because the fuel is not being atomized enough, and is  

"clumping" together and cannot break apart to go to #3 and 4? This is  

hard to visualize/imagine for me. I guess I do not understand your  

description of the "tapered plenum" and how it works.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 600.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

New skis done and flying

do not archive



On Jan 14, 2009, at 5:15 PM, Peter Harris wrote:



[quote] 

 <peterjfharris(at)bigpond.com>



 Lynn my tests were done on the ground in static runs. You could try  

 the

 throttle movement test on the ground for comparison.

 I think after many hours of ground runs the last test I did with  

 the plenum

 proves that resistance in the Jab collector is affecting  

 performance, as

 follows:



 1.	Breakdown at WOT is caused by an unrestricted rush of fuel to the

 end of the plenum to #1 and 2. In use of the tapered plenum there  

 is only

 one way to stop spectacular engine breakdown at WOT and that is by  

 fitting a

 full width baffle 35mm wide and 30mm from the entry inside the plenum.

 2.	The baffle neutralizes the effect of the butterfly so that the last

 1" of throttle has no effect. The baffle is acting like a partly  

 closed

 butterfly downstream. Without the baffle, throttle increases power  

 up to the

 point of breakdown ie there is no dead throttle.

 3.	Similarly the last 1" of throttle into the Jab. collector has no

 effect but because of internal losses there is normally no  

 breakdown at WOT,

 only #1 and 2 go rich.



 My tests were conducted on the ground static. I am using a 55 X 72"  

 prop. on

 the Quickie which climbs at 1500FPM and cruises at 170KTS at  

 2950RPM WOT.

 You can appreciate why I am trying to make sure the engine is doing  

 it's

 best. The engine is still very tight when hot. It has done about  

 50hours.



 Peter

 --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Wed Jan 14, 2009 8:17 pm Post subject: 3300A - Full Throttle Roughness

Lynn

The prop is 55 dia X 72 pitch.

The 500KG gross Quickie is a fast 2 seat low drag Rutan canard design and

rated at 200MPH when powered by an 0-200. Performance is similar to a

Varieze but with a shorter take off roll. The J 3300 advertises an extra

20HP and I am looking for the extra air speed but not satisfied the engine

is performing to full potential.

Feeding from a Jenvey throttle body with two injectors at WOT I am getting

much the same problem as referred when the Bing is fully open. Rough running

and according to my plugs it is caused by a surge of fuel to #1 and 2 at the

end of the plenum. With the plenum the rough running is extreme and causes

breakdown. With the Jab collector the effect is masked by losses in the

collector. As referred before I can fix the problem with the use of a large

baffle but this restricts the effect of the throttle and there is a loss of

power. There appears to me to be a similar loss in the Jab collector.

Therefore I don't think it is a Bing problem but based on the tests I have

done with a tapered plenum I think the problem is due to the design of the

plenum (also the Jab collector) by attempting to feed from the end and with

outlets along each side. By contrast if we look at the 0-200 the feed is an

updraft central between the four outlets and with equal length headers this

makes for uniform distribution over the full power range. 

Near WOT when the butterfly is near level the Bing (and the Jenvey) fuel/air

charge although atomized the fuel droplets have sufficient energy to travel

to the end of the system and over richen #1 and 2.

The reason to taper the plenum is to attempt to get a uniform pressure

gradient along the axis allowing for expansion of the charge at each pair of

outlets. Take a look at a Dyson vacuum cleaner. It works well for air and it

works well when bench tested using water in a pressure paint spray gun but

apparently not for the fuel/air charge at the higher velocity under WOT. 

When the butterfly is deflected further to reduce throttle the turbulence is

increased and the charge is more evenly distributed. Using the plenum

without the internal baffle I found that the butterfly position is critical

and the breakdown is sudden and complete.

I also tried with fuel pressure increased to 60PSI for better atomization

but without success.

Hope that helps, I tried to attach a pic of the plenum which does not look

very pretty but is sexy on the inside.

Re engine hours you are right I have spent too long on the ground

experimenting.

Peter



--

PLENUM_TAPERED_005.jpg

Description:

Filesize:

594.97 KB

Viewed:

687 Time(s)

jetboy

Joined: 22 Jul 2006
Posts: 233

Posted: Wed Jan 14, 2009 9:01 pm Post subject: Re: 3300A - Full Throttle Roughness

If this is any help I recall reading on the lists about the rubber coupling from carb to intake spider having a groove or step inside where fuel droplets cavitate  and sit in a pool at times of operation. some have dealt to this by fitting an 'inner' sleeve tapered to make a smooth transition with no step.



Ralph

_________________
Ralph - CH701 / 2200a

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Thu Jan 15, 2009 3:24 am Post subject: 3300A - Full Throttle Roughness

Andy alerted us to this problem, and when I looked at mine last year,  

I found that there was a cast-in ridge that effectively bridges that  

gap between the carb and the plenum. Although not a smooth  

transition, it does fill the gap and thus avoids the "groove or step"  

you mentioned. My 2200 serial number is 2062, delivered  in August  

2005, just to put it in a time perspective.



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 600.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

New skis done and flying

do not archive



On Jan 15, 2009, at 12:01 AM, jetboy wrote:



 	  Quote: 	
		   

 <sanson.r(at)xtra.co.nz>



 If this is any help I recall reading on the lists about the rubber  

 coupling from carb to intake spider having a groove or step inside  

 where fuel droplets cavitate  and sit in a pool at times of  

 operation. some have dealt to this by fitting an 'inner' sleeve  

 tapered to make a smooth transition with no step.



 Ralph



 --------

 Ralph - CH701 / 2200a





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 24860#224860

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

andy(at)suncoastjabiru.co
Guest

Posted: Thu Jan 15, 2009 7:12 am Post subject: 3300A - Full Throttle Roughness

Lynn,



Actually, the gap between the end of the carb. and the start of the intake

adapter can be a bit of an issue; the rubber coupler which bridges this gap,

which is necessary for vibration isolation, creates a definite groove

(annulus?) into which liquid fuel floods and then exits at any angle

depending on the influence of the airstream going through. One of our OEM

customers did extensive testing using a clear plastic transition and

reported that, at the point of exit from the carb, the fuel is still very

much in liquid form, and not the homogenous fuel/air vapour we might expect

from the theory. Of course, the mixture becomes more (er) mixed as it

travels up the intake tubes but Peter is absolutely right; there is little

opportunity for the fuel / air 'mix' to divide itself 50/50 by the vertical

splitter in the induction in the short distance it travels from the jet,

especially if the air going through the carb. is at all twisting. This extra

(though small) reservoir in the coupling-gap therefore adds to the

uncertainty of how the mixture splits left-and-right, often leading to an

imbalance of mixture at the cylinders. The same OEM fitted oxygen (lambda)

sensors on the 3300's combined exhaust headers (i.e. before the current

individual pipe setup), and found that there could be a ratio of 10:1 on one

side and as high as 16:1 on the other, where Jabiru's own reported 'ideal'

ratio is about 14:1. Interestingly, the lean and rich sides would swap over

as rpm increased, more-or-less proving the view that fuel distribution was

uneven before the splitter. I saw graphs of this a couple of years ago, and

the source of the analysis is impeccable. Now that we have comprehensive

engine monitoring and EGTs on all cylinders, it's easy to see these effects

through the rev. range as you fly. Even better are monitors like the GRT

Horizon/EFIS instrument which can graph EGT in real-time so you can see the

effects of mixture distribution at different power settings. 

As I suggested in the post a while back, we found some success by inserting

a filler-ring made of rigid plastic (about the same consistency as the

coupler) which would fill said gap and provide a smoother bore. It wasn't a

complete fix, but definitely improved mixture distribution. Ideally, the

carb delivering into a plenum about 30% of the engine's cubic capacity

should give a better opportunity for fuel and air to mix, but space and

neatness of design precludes this. Jabiru's original plenum on the 2200 and

very few 3300s wasn't a success as the fuel in liquid state would tend to be

thrown to the front of the plenum and then run along the walls and up the

front two intake tubes, so the front cylinders were richer than the back.

Now, if the intake tubes protruded into the plenum by a few mm, the liquid

fuel wouldn't run up 'em, would it? 



The experts at Jabiru were fed all this information at the time, but no

doubt had better reasons than me for keeping the design, and why not? It's

theirs!



Andy



--

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Thu Jan 15, 2009 3:02 pm Post subject: 3300A - Full Throttle Roughness

Andy,

That is a very informative post. 

I have been testing with a twin injector throttle body feeding an

unobstructed plenum, then for comparison feeding the Jab collector. My

fuel/air mix should be better, in fact I tried 60PSI for greater

atomization, but the charge entered the plenum and too much of the fuel

carried through to over richen #1 and 2 near WOT.

This is an issue independent of the splitter or the type of turbulence.

I think it is happening because near WOT a proportion of the fuel droplets

have enough energy to accelerate through the plenum (or the collector) until

they reach the end.

This is similar to the principle used by Dyson when dust is separated from

the air stream by using it's kinetic energy in a cyclone.

After endless tests I think the problem is due to the fact that we have an

end fed plenum (or collector).

I plan to reconfigure my plenum for bottom feed similar to the 0-200, but

headers will still be unequal and it will not be easy to target the charge

for uniform distribution between the 6 outlets.

Peter



--

jd(at)lawsonimaging.ca
Guest

Posted: Thu Jan 15, 2009 4:47 pm Post subject: 3300A - Full Throttle Roughness

Peter Harris wrote:

 	  Quote: 	
		   

 

 Andy,

 That is a very informative post. 

 I have been testing with a twin injector throttle body feeding an

 unobstructed plenum, then for comparison feeding the Jab collector. My

 fuel/air mix should be better, in fact I tried 60PSI for greater

 atomization, but the charge entered the plenum and too much of the fuel

 carried through to over richen #1 and 2 near WOT.

 This is an issue independent of the splitter or the type of turbulence.

 I think it is happening because near WOT a proportion of the fuel droplets

 have enough energy to accelerate through the plenum (or the collector) until

 they reach the end.

 This is similar to the principle used by Dyson when dust is separated from

 the air stream by using it's kinetic energy in a cyclone.

 After endless tests I think the problem is due to the fact that we have an

 end fed plenum (or collector).

 I plan to reconfigure my plenum for bottom feed similar to the 0-200, but

 headers will still be unequal and it will not be easy to target the charge

 for uniform distribution between the 6 outlets.

 Peter




	


Just wondering... there seems to be a preponderance of posting on this 

list that has to do with Bing carb 

tuning/jetting/adjusting/modifying/etc. Has anyone considered an 

alternative? AeroConversion's AeroCarb comes to mind :') I'm quite happy 

with mine (Sonex/3300/AeroCarb), and I know that there are  many other 

Sonex/3300 drivers that are, also.

-- 

Regards,  J.



-------------------------------------------------

J. Davis, M.Sc. (computer science)

*NIX consulting, SysAdmin

-------------------------------------------------



The day Microsoft makes a product that doesn't suck, is the day they 

make a vacuum cleaner.

don(at)pcperfect.com
Guest

Posted: Thu Jan 15, 2009 8:06 pm Post subject: 3300A - Full Throttle Roughness

I'd love to hear any real world results of the AeroCarb on Zenith 601s.



I also personally would love a fuel ejected fully computerized control

setup for the 3300 as well!!!!!



Don

--

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Thu Jan 15, 2009 8:46 pm Post subject: 3300A - Full Throttle Roughness

J

I would recommend against using Aerocarb especially on the J3300 based on

personal experience. I was supplied with an Aerocarb with no Teflon liner.

The slide worked on anodized metal to metal and jammed hard.

The slide is pulled and pushed by an outrigged lever which causes the slide

to twist and jam whenever pressure is applied. The attachment to cable is

off centre and not even co planar with the slide.

A Teflon liner is offered on the website but my several requests were

ignored.

I packed it with grease but it still jammed under the vacuum at low throttle

settings and any attempt to quickly open throttle for a missed approach

makes it jam harder because of the offset cable attachment.

I attempted to discuss changes to the design but was abused. I have a copy

of the correspondence.

When I asked for a refund I was told to sell it on eBay.

I would not have the conscience to give it away .

Peter 



--

Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Fri Jan 16, 2009 3:12 am Post subject: 3300A - Full Throttle Roughness

But do you remember, Andy, when I reported back in about April of  

last year that my rubber coupler had a built-up ridge that filled  

this gap? I mentioned this and you said that the coupler supplier  

must have made this change in the later models. Here is picture of  

that ridge. It is the square-ish ridge between the two humps that fit  

into the grooves of the carb and the intake adapter.



It is a bit hard to visualize because of the coupler being all black,  

but it's there. I show this to let folks know that maybe by changing  

to this style coupler that maybe some of the imbalance might be  

modified in their engines if they presently have the coupler which  

doesn't have this "gap-filling" ridge. What do you think?



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 600.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

New skis done and flying

do not archive



On Jan 15, 2009, at 10:10 AM, Andy Silvester wrote:



[quote] 

 <andy(at)suncoastjabiru.com>



 Lynn,



 Actually, the gap between the end of the carb. and the start of the  

 intake

 adapter can be a bit of an issue; the rubber coupler which bridges  

 this gap,

 which is necessary for vibration isolation, creates a definite groove

 (annulus?) into which liquid fuel floods and then exits at any angle

 depending on the influence of the airstream going through. One of  

 our OEM

 customers did extensive testing using a clear plastic transition and

 reported that, at the point of exit from the carb, the fuel is  

 still very

 much in liquid form, and not the homogenous fuel/air vapour we  

 might expect

 from the theory. Of course, the mixture becomes more (er) mixed as it

 travels up the intake tubes but Peter is absolutely right; there is  

 little

 opportunity for the fuel / air 'mix' to divide itself 50/50 by the  

 vertical

 splitter in the induction in the short distance it travels from the  

 jet,

 especially if the air going through the carb. is at all twisting.  

 This extra

 (though small) reservoir in the coupling-gap therefore adds to the

 uncertainty of how the mixture splits left-and-right, often leading  

 to an

 imbalance of mixture at the cylinders. The same OEM fitted oxygen  

 (lambda)

 sensors on the 3300's combined exhaust headers (i.e. before the  

 current

 individual pipe setup), and found that there could be a ratio of  

 10:1 on one

 side and as high as 16:1 on the other, where Jabiru's own reported  

 'ideal'

 ratio is about 14:1. Interestingly, the lean and rich sides would  

 swap over

 as rpm increased, more-or-less proving the view that fuel  

 distribution was

 uneven before the splitter. I saw graphs of this a couple of years  

 ago, and

 the source of the analysis is impeccable. Now that we have  

 comprehensive

 engine monitoring and EGTs on all cylinders, it's easy to see these  

 effects

 through the rev. range as you fly. Even better are monitors like  

 the GRT

 Horizon/EFIS instrument which can graph EGT in real-time so you can  

 see the

 effects of mixture distribution at different power settings.

 As I suggested in the post a while back, we found some success by  

 inserting

 a filler-ring made of rigid plastic (about the same consistency as the

 coupler) which would fill said gap and provide a smoother bore. It  

 wasn't a

 complete fix, but definitely improved mixture distribution.  

 Ideally, the

 carb delivering into a plenum about 30% of the engine's cubic capacity

 should give a better opportunity for fuel and air to mix, but space  

 and

 neatness of design precludes this. Jabiru's original plenum on the  

 2200 and

 very few 3300s wasn't a success as the fuel in liquid state would  

 tend to be

 thrown to the front of the plenum and then run along the walls and  

 up the

 front two intake tubes, so the front cylinders were richer than the  

 back.

 Now, if the intake tubes protruded into the plenum by a few mm, the  

 liquid

 fuel wouldn't run up 'em, would it?



 The experts at Jabiru were fed all this information at the time,  

 but no

 doubt had better reasons than me for keeping the design, and why  

 not? It's

 theirs!



 Andy



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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

andy(at)suncoastjabiru.co
Guest

Posted: Fri Jan 16, 2009 6:24 am Post subject: 3300A - Full Throttle Roughness

You're right, Lynn, apologies. Must be advancing years or British beer for

the last couple of months that have taken their toll. Back in Brazil very

soon with a healthier diet and more brain exercise, no doubt.  There may

well be others with the older couplers and the 'gap' who might be interested

though. Unfortunately, the only way to find out is to remove it and look

inside.

Cheers, Andy 



--

jd(at)lawsonimaging.ca
Guest

Posted: Fri Jan 16, 2009 6:25 am Post subject: 3300A - Full Throttle Roughness

Peter Harris wrote:

[quote] 

 

 J

 I would recommend against using Aerocarb especially on the J3300 based on

 personal experience. I was supplied with an Aerocarb with no Teflon liner.

 The slide worked on anodized metal to metal and jammed hard.

 The slide is pulled and pushed by an outrigged lever which causes the slide

 to twist and jam whenever pressure is applied. The attachment to cable is

 off centre and not even co planar with the slide.

 A Teflon liner is offered on the website but my several requests were

 ignored.

 I packed it with grease but it still jammed under the vacuum at low throttle

 settings and any attempt to quickly open throttle for a missed approach

 makes it jam harder because of the offset cable attachment.

 I attempted to discuss changes to the design but was abused. I have a copy

 of the correspondence.

 When I asked for a refund I was told to sell it on eBay.

 I would not have the conscience to give it away .

 Peter 

 

 --

JOE RONCO

Joined: 04 Aug 2007
Posts: 31
Location: CENTENNIAL COLORADO

Posted: Fri Jan 16, 2009 8:22 am Post subject: 3300A - Full Throttle Roughness

Or you could trade it in for a new UL Power (www.ulpower.com) Model UL350i (same or better performance as the 3300) and get EFI/FADEC as standard. No messing with carburetors, carb heat or carb ice, fuel distribution etc. ULP has also introduced redundancy options for the ECU. 

 

   

See: http://www.ulpower.com/ul260i-qa-ecu.htm. Click on link at bottom of page for schematics of optional ECU arrangements.  

   

See attachments for preliminary UL350i specifications and performance. ULP is fine tuning/optimizing the UL350i design with release to the market expected 2Q/3Q 2009.  

   

Joe R  

   

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Lynn Matteson

Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan

Posted: Fri Jan 16, 2009 9:57 am Post subject: 3300A - Full Throttle Roughness

"Back in Brazil"? R U UK'ing it now?



Lynn Matteson

Kitfox IV Speedster, taildragger

Jabiru 2200, #2062, 600.2 hrs

Sensenich 62x46

Electroair direct-fire ignition system

New skis done and flying

do not archive



On Jan 16, 2009, at 9:24 AM, Andy Silvester wrote:



[quote] 

 <andy(at)suncoastjabiru.com>



 You're right, Lynn, apologies. Must be advancing years or British  

 beer for

 the last couple of months that have taken their toll. Back in  

 Brazil very

 soon with a healthier diet and more brain exercise, no doubt.   

 There may

 well be others with the older couplers and the 'gap' who might be  

 interested

 though. Unfortunately, the only way to find out is to remove it and  

 look

 inside.

 Cheers, Andy



 --

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Fri Jan 16, 2009 12:47 pm Post subject: 3300A - Full Throttle Roughness

J 

The throttle quadrant does nothing to solve the basic design fault which is

due to the cable attachment off centre and not co planar causing the slide

to twist when moved, and the increased load due to friction on the slide

when it is moved at low throttle settings.

But it is not only the design issues but also the attitude of the CEO as he

was not prepared to supply me with the Teflon insert listed on his web site

and resorted to personal abuse when I suggested some design changes that

would solve the problem.

There have been engine failures and a forced landing due to jammed slides.

Peter



--

sonex229(at)windstream.ne
Guest

Posted: Fri Jan 16, 2009 3:24 pm Post subject: 3300A - Full Throttle Roughness

BALONEY TO your failed engine statement due to the Aero-Vee carb. Verify one 

that can be proven to be caused by the carb,,..Regards Wayne

---

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