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EGTs and fuel quality

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cffd(at)pgrb.com
Guest

Posted: Sat Apr 19, 2008 8:16 am Post subject: EGTs and fuel quality

Lynn,



The 4 inch comment has my 2200 running its best.  My SN is 988, Bob Vossman 

has SN 8XX.  He has more than one groove in his needle.  I think the carb 

data from Jabiru also shows mine with 3 grooves.  My needle is a Bing and 

not from the Jab tuning kit.  I will check my egt's one more time and then 

attack the carb, if need be.



Chuck

 	  Quote: 	
		   ________________________________  Message 2 

 _____________________________________

 Time: 12:10:47 PM PST US

 From: Lynn Matteson <lynnmatt(at)jps.net>

 Subject: Fwd: [jabiruengines] Re: EGTs and fuel quality

 Begin forwarded message:



> From: Lynn Matteson <lynnmatt(at)jps.net>

> Date: April 18, 2008 2:37:32 PM GMT-04:00

> To: jabiruengines(at)yahoogroups.com

> Subject: Re: [jabiruengines] Re: EGTs and fuel quality

>

> Chuck-

> You may not have another groove to move the clip to...mine only had

> one groove, but I'm serial #2062, with 40mm Bing.

> I've got the Bing Aircraft Manual (if I could put my hands on my

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Lynn Matteson

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

Posted: Sat Apr 19, 2008 9:39 am Post subject: EGTs and fuel quality

Chuck-

I just flew my newly-modified and installed air duct (from airbox to  

carb) and it works fine. I'd say great, but it didn't even out the  

EGT's like I hoped, but it did *seem* to give me more WOT rpm. Of  

course the weather has changed since I last checked for WOT rpm, but  

before I'd have to point the nose down just a little to get 3000 rpm.

Today I could fly level and get 3130 rpm. Again, the air density  

might have something to do with it. I'm also climbing out at about  

90-100 rpm higher. It's a bitch to take down performance figures in  

the cold air, and by the time the changes are made, the weather does  

an "about face," and you have squat to compare to. Suffice it to say,  

the engine runs good now, so be it air-straightening vanes or better  

weather, I'm happy. One other thing I'm going to try...just for  

kicks...is to swap the SCAT hose for some SCEET hose from airbox to  

the vaned air duct. I just saw some SCEET hose, and that stuff is  

smooth inside! For just a few bucks more per foot, I'm going for it.

After the initial flight today, I also changed to a 2.78 needle jet,  

up from the original 2.76 jet. (I had done this a few weeks ago, but  

changed float level too, and the combo had the engine stumbling, so I  

removed it at the time) That didn't change the EGT's all that much,  

but it did chase the hot EGT from #4 over to #3. I wasn't in the mood  

to write down a bunch of figures at the time, but I will, and report  

what I find.

My carb had the 2005 Economy Kit on board when I bought it, and the  

jet and needle sizes were etched on the side of the carb. My needle  

number ended in -1, meaning one groove, as I understand it, and  

indeed it was a one-groove needle.

Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/490+ hrs

On Apr 19, 2008, at 12:13 PM, Chuck Deiterich wrote:

 	  Quote: 	

 <cffd(at)pgrb.com>

 Lynn,

 The 4 inch comment has my 2200 running its best.  My SN is 988, Bob  

 Vossman has SN 8XX.  He has more than one groove in his needle.  I  

 think the carb data from Jabiru also shows mine with 3 grooves.  My  

 needle is a Bing and not from the Jab tuning kit.  I will check my  

 egt's one more time and then attack the carb, if need be.

 Chuck

> ________________________________  Message 2  

> _____________________________________

> Time: 12:10:47 PM PST US

> From: Lynn Matteson <lynnmatt(at)jps.net>

> Subject: Fwd: [jabiruengines] Re: EGTs and fuel  

> quality

> Begin forwarded message:

>

>> From: Lynn Matteson <lynnmatt(at)jps.net>

>> Date: April 18, 2008 2:37:32 PM GMT-04:00

>> To: jabiruengines(at)yahoogroups.com

>> Subject: Re: [jabiruengines] Re: EGTs and fuel quality

>>

>> Chuck-

>> You may not have another groove to move the clip to...mine only had

>> one groove, but I'm serial #2062, with 40mm Bing.

>> I've got the Bing Aircraft Manual (if I could put my hands on my

- The Matronics JabiruEngine-List Email Forum -

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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

Peter H

Joined: 20 Mar 2007
Posts: 197

Posted: Sat Apr 19, 2008 2:41 pm Post subject: EGTs and fuel quality

Lynn 

I have also been chasing a better fuel/air distribution and have finished

with the Bing because I was looking for better control of mixture. I have

been test flying with a TBI conversion using a 45mm throttle body with two

injectors controlled by ECU in the Q-200 airframe powered by the J3300.

I have total control of mix and can over ride the fuel map using a

potentiometer.

But EGT is still uneven and it varies according to engine load and rpm. I am

monitoring EGT at #5 and #6 and see even T at top of climb but then have

seen up to 100degC variance as the load and rpm changes in level flight. I

discussed this with one of the engineers at the factory. He has seen up to

200 deg variance. His advice is to experiment with the intake hose as you

have done but I do not believe it will solve for even EGT. The variance is

worst when the engine is lean but the Bing has been set up to go rich above

2700rpm. When my EGT variance was at its worst the engine began to shake

because of the uneven power strokes R to L and I think this condition could

contribute to the fly wheel bolt problem.

Like you I have been testing for best rpm at WOT but I am over propped

somewhat and the engine has only done about 40 hrs. It is too tight to re

start when hot. I am getting a TAS of 184 KTS in the Quickie at 2950 RPM WOT

but I think there is more potential.

I think the uneven mix is caused by the lack of a reasonable sized induction

manifold. The jab has only a collector of less than 1/2L capacity and

induction pulses as valves close are interfering with the incoming fuel air

mix. The condition varies with RPM.

As an experiment I am making dual manifolds with a cross pipe using standard

SS tube fittings in 64mm diameter x 1.6, The throttle body will feed the

cross pipe from a 63mm tee. Total capacity is about 3.5L.

I hope to test fly within a couple of weeks and will be able to report with

pics then.

If successful I have since found a source prepared to make the fittings in

1.6mm Al tube. My SS manifold has added about 1.5KG net to the weight.The

fittings are expensive .

Peter

--

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Lynn Matteson

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

Posted: Sat Apr 19, 2008 3:18 pm Post subject: EGTs and fuel quality

Sounds exciting, Peter...be sure to let us know how it goes.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/490+ hrs

do not archive

On Apr 19, 2008, at 6:37 PM, Peter Harris wrote:



[quote] 

 <peterjfharris(at)bigpond.com>



 Lynn

 I have also been chasing a better fuel/air distribution and have  

 finished

 with the Bing because I was looking for better control of mixture.  

 I have

 been test flying with a TBI conversion using a 45mm throttle body  

 with two

 injectors controlled by ECU in the Q-200 airframe powered by the  

 J3300.

 I have total control of mix and can over ride the fuel map using a

 potentiometer.

 But EGT is still uneven and it varies according to engine load and  

 rpm. I am

 monitoring EGT at #5 and #6 and see even T at top of climb but then  

 have

 seen up to 100degC variance as the load and rpm changes in level  

 flight. I

 discussed this with one of the engineers at the factory. He has  

 seen up to

 200 deg variance. His advice is to experiment with the intake hose  

 as you

 have done but I do not believe it will solve for even EGT. The  

 variance is

 worst when the engine is lean but the Bing has been set up to go  

 rich above

 2700rpm. When my EGT variance was at its worst the engine began to  

 shake

 because of the uneven power strokes R to L and I think this  

 condition could

 contribute to the fly wheel bolt problem.

 Like you I have been testing for best rpm at WOT but I am over propped

 somewhat and the engine has only done about 40 hrs. It is too tight  

 to re

 start when hot. I am getting a TAS of 184 KTS in the Quickie at  

 2950 RPM WOT

 but I think there is more potential.

 I think the uneven mix is caused by the lack of a reasonable sized  

 induction

 manifold. The jab has only a collector of less than 1/2L capacity and

 induction pulses as valves close are interfering with the incoming  

 fuel air

 mix. The condition varies with RPM.

 As an experiment I am making dual manifolds with a cross pipe using  

 standard

 SS tube fittings in 64mm diameter x 1.6, The throttle body will  

 feed the

 cross pipe from a 63mm tee. Total capacity is about 3.5L.

 I hope to test fly within a couple of weeks and will be able to  

 report with

 pics then.

 If successful I have since found a source prepared to make the  

 fittings in

 1.6mm Al tube. My SS manifold has added about 1.5KG net to the  

 weight.The

 fittings are expensive .

 Peter

 --

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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

andy(at)suncoastjabiru.co
Guest

Posted: Sun Apr 20, 2008 8:47 am Post subject: EGTs and fuel quality

Lynn,



Good work on the improvements! I'm sure many of us have found the same

situation of not knowing *exactly* what brings better performance,

especially when we are talking about a few % only, but those RPM increases

are significant. A note about SCEET ducting; I've used it with success on

the intake. Someone once told me that SCAT ducting has an equivalent

resistance of 23, meaning that 1 foot of SCAT ducting has the same

resistance to airflow as 23 feet of smooth-bore pipe! SCEET will be better,

but bear in mind one down-side which I'm sure won't affect you. The inner

'skin' of the duct can perish and suck flat if given enough time and bad

maintenance. It's a fair point, and a few A&Ps have told me it's a no-no to

use it on anything below ambient pressure, i.e. a carburettor intake. My

response (while being sympathetic to the argument) was that most

Experimental aircraft get better maintenance than certificated types(!) and

therefore the idea of a piece of duct not being internally inspected for

(say) 5 years or more is less likely in our world (.....or is it??!!)



Keep up the good work, Andy



--

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Lynn Matteson

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

Posted: Sun Apr 20, 2008 10:30 am Post subject: EGTs and fuel quality

Thanks for the input, Andy....I sure didn't know about, or probably  

would not have thought about, the inner skin sucking in, but it makes  

sense. I'll give that one some thought, but like you said, maintain  

it and it'll probably be OK.



Lynn Matteson

Grass Lake, Michigan

Kitfox IV Speedster  w/Jabiru 2200

flying w/490+ hrs

On Apr 20, 2008, at 12:43 PM, Andy Silvester wrote:



[quote] 

 <andy(at)suncoastjabiru.com>



 Lynn,



 Good work on the improvements! I'm sure many of us have found the same

 situation of not knowing *exactly* what brings better performance,

 especially when we are talking about a few % only, but those RPM  

 increases

 are significant. A note about SCEET ducting; I've used it with  

 success on

 the intake. Someone once told me that SCAT ducting has an equivalent

 resistance of 23, meaning that 1 foot of SCAT ducting has the same

 resistance to airflow as 23 feet of smooth-bore pipe! SCEET will be  

 better,

 but bear in mind one down-side which I'm sure won't affect you. The  

 inner

 'skin' of the duct can perish and suck flat if given enough time  

 and bad

 maintenance. It's a fair point, and a few A&Ps have told me it's a  

 no-no to

 use it on anything below ambient pressure, i.e. a carburettor  

 intake. My

 response (while being sympathetic to the argument) was that most

 Experimental aircraft get better maintenance than certificated types 

 (!) and

 therefore the idea of a piece of duct not being internally  

 inspected for

 (say) 5 years or more is less likely in our world (.....or is it??!!)



 Keep up the good work, Andy



 --

- 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

_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM

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