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Full Thorttle Roughness Issue.

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don(at)pcperfect.com
Guest

Posted: Thu Jan 15, 2009 8:29 pm Post subject: Full Thorttle Roughness Issue.

Clive,  

   

I've had some positive results in fixing my roughness issue, but I'm still working out the details.  

   

Here's what I've got so far...  

   

I appear to have an air intake issue. Flying without the air intake system and just the carb open to the cowling area and the plane flies extremely smooth. This fixed the roughness for everything except the last 1/4" of throttle travel. Repitching the prop so I had an in flight max of ~3300 RPM fixed the last 1/4" of roughness. Before the pitch change, my max out in straight and level was 3000 RPM.  

   

I'm going to be installing various modified air intake setups over the next few weeks and will post my results.  

   

For what it's worth, after re-pitching and flying without the air intake system, the plane is amazing. I've gained about 5 to 10 MPH in speed and 300 feet per minute or more in climb and the engine is much smoother in all RPM ranges. I'm really excited about getting a good intake system designed  now that I'm seen the "other side" of this engine.  

   

Don  

   

       

From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of James, Clive R

 Sent: Thursday, January 15, 2009 15:22

 To: jabiruengine-list(at)matronics.com

 Subject: RE: Full Thorttle Roughness Issue.  

  

  

   

Don, I don't have a functioning EGT but what you describe with RPM and roughness is just what I'm experiencing on my Esqual with a 3300 Jabiru #1460. I've only got 15 hours on the engine and am chasing other issues for now so I'm very interested in the resolution. From what I've heard in the past and read about the Bing I'm in the main jet size change solution camp. Very interested in how you get on working the solution.   

   

Regards, Clive  

       

  

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

 Sent: 14 January 2009 16:19

 To: jabiruengine-list(at)matronics.com

 Subject: Full Thorttle Roughness Issue...  

I just wanted to take  moment and thank everyone that responded to my question both on-list and off (WOW - just absolutely amazing the response - THANK YOU!).  

   

From the various suggestions I decided that I needed to do a bit more investigation...  

   

During take-off AND WOT the EGTs on the right side of my engine are significantly higher than the left. The max difference being ~1400 versus 1100F. However, during cruise, everything tends to even out but now my left side (or at least cylinders #6 and #4) have higher EGTs than the right side in general (~1359  verus 1290).   

   

What is interesting is that my max RPM on take-off at WOT is ~2,850 and there is no roughness at all despite the same EGT profile. In contrast, when I do WOT in cruise the RPM maxes out at 3,000 and the roughness is pretty bad and starts at about 2900RPM and gets worse as the RPM increases. Also, pulling back so that the RPM is less than 2900 always gets rid of the roughness.  

   

So while the EGT profiles are essentially the same for both WOT situations, it would appear that when the engine is capable of going above 2900 RPM that the roughness occurs.   

   

Any thoughts?  

   

If interested, here are the two plot graphs for take-off and full power cruise:  

   

http://support.pcperfect.com/EGTs-TakeOff.pdf  

http://support.pcperfect.com/EGTs-WOT-Cruise.pdf  

   

Thanks!

 Don  

   

    	  Quote: 	
		    href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.matronics.com/Navigator?JabiruEngine-Listhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/chttp://www.matronics.com/Navigator?JabiruEngine-Listhttp://forums.matronics.com         - List Contribution Web generous nbsp;           �            --> http://www.matronics.com/c=[/b] 	
  

No virus found in this incoming message.

 Checked by AVG - http://www.avg.com

 1/15/2009 07:46  

      [quote][b]

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Clive J

Joined: 03 Nov 2007
Posts: 340
Location: UK

Posted: Thu Jan 15, 2009 11:05 pm Post subject: Full Thorttle Roughness Issue.

Thanks Don, mine is just the last bit and only at high  revs. In the climb at 2800 it's smooth enough but then that a different  situation to 3000 plus.

 I will drop off the scat from the carb for elimination of  that issue, that's a great idea.

 I have oversized scat tube on the carb which I'm hoping  will help with airflow but then I suppose that could be the cause.  

 Regards, Clive



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

Sent: 16 January 2009 04:27

To:  jabiruengine-list(at)matronics.com

Subject: RE: Full  Thorttle Roughness Issue.

 

  

Clive, 

  

I've had some positive results  in fixing my roughness issue, but I'm still working out the  details. 

  

Here's what I've got so  far... 

  

I appear to have an air intake  issue. Flying without the air intake system and just the carb open to the  cowling area and the plane flies extremely smooth. This fixed the roughness for  everything except the last 1/4" of throttle travel. Repitching the prop so I had  an in flight max of ~3300 RPM fixed the last 1/4" of roughness. Before the pitch  change, my max out in straight and level was 3000 RPM. 

  

I'm going to be installing  various modified air intake setups over the next few weeks and will post my  results. 

  

For what it's worth, after  re-pitching and flying without the air intake system, the plane is amazing. I've  gained about 5 to 10 MPH in speed and 300 feet per minute or more in climb and  the engine is much smoother in all RPM ranges. I'm really excited about getting  a good intake system designed  now that I'm seen the "other side" of this  engine. 

  

Don 

  

    

From:  owner-jabiruengine-list-server(at)matronics.com  [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of James,  Clive R

Sent: Thursday, January 15, 2009 15:22

To:  jabiruengine-list(at)matronics.com

Subject: RE: Full  Thorttle Roughness Issue.



 

  

Don, I  don't have a functioning EGT but what you describe with RPM and roughness is  just what I'm experiencing on my Esqual with a 3300 Jabiru #1460. I've only  got 15 hours on the engine and am chasing other issues for now so I'm very  interested in the resolution. From what I've heard in the past and read about  the Bing I'm in the main jet size change solution camp. Very interested in how  you get on working the solution.  

  

Regards,  Clive 

    

 

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

Sent: 14 January 2009 16:19

To:  jabiruengine-list(at)matronics.com

Subject: Full  Thorttle Roughness Issue... 

I just wanted to take  moment and thank everyone that  responded to my question both on-list and off (WOW - just absolutely amazing the  response - THANK YOU!). 

  

From the various suggestions I decided that I needed to do a  bit more investigation... 

  

During take-off AND WOT the EGTs on the right side of my  engine are significantly higher than the left. The max difference being ~1400  versus 1100F. However, during cruise, everything tends to even out but now my  left side (or at least cylinders #6 and #4) have higher EGTs than the right side  in general (~1359  verus 1290).  

  

What is interesting is that my max RPM on take-off at WOT is  ~2,850 and there is no roughness at all despite the same EGT profile. In  contrast, when I do WOT in cruise the RPM maxes out at 3,000 and the roughness  is pretty bad and starts at about 2900RPM and gets worse as the RPM increases.  Also, pulling back so that the RPM is less than 2900 always gets rid of the  roughness. 

  

So while the EGT profiles are essentially the same for both  WOT situations, it would appear that when the engine is capable of going above  2900 RPM that the roughness occurs.  

  

Any thoughts? 

  

If interested, here are the two plot graphs for take-off and  full power cruise: 

  

http://support.pcperfect.com/EGTs-TakeOff.pdf 

http://support.pcperfect.com/EGTs-WOT-Cruise.pdf 

  

Thanks!

Don 

  

  	  Quote: 	
		    href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.matronics.com/Navigator?JabiruEngine-Listhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/c    �    - List Contribution Web generous nbsp;           �            --> http://www.matronics.com/c= 	
 

No virus  found in this incoming message.

Checked by AVG -  http://www.avg.com

1/15/2009 07:46

 	  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

	
  [quote][b]

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zeprep251(at)aol.com
Guest

Posted: Fri Jan 16, 2009 5:17 am Post subject: Full Thorttle Roughness Issue.

Here is an interesting web site,if  they only would supply a set up for the Jabiru. (Experimental fuel injection.com).Lots of help for Rotax. 

 

   

 

   

 

 --

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don(at)pcperfect.com
Guest

Posted: Fri Jan 16, 2009 7:19 am Post subject: Full Thorttle Roughness Issue.

David,



Great tail number, my is N601DX 



It may be that the warm arm or additional air input to the airbox causes

less turbulence at the carb intake and distributes the air/fuel mix

better ???



Don

--

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don(at)pcperfect.com
Guest

Posted: Fri Jan 16, 2009 7:30 am Post subject: Full Thorttle Roughness Issue.

Clive,  

   

I don't know if it matters, but I also plugged up the air intake scat inlet with a hand towel to prevent a bunch of air blowing right behind the carb intake for my tests. (My intake output sits on the firewall and the output points at angle towards the carb.)  

   

Don  

   

       

From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of James, Clive R

 Sent: Friday, January 16, 2009 00:04

 To: jabiruengine-list(at)matronics.com

 Subject: RE: Full Thorttle Roughness Issue.  

  

  

   

Thanks Don, mine is just the last bit and only at high revs. In the climb at 2800 it's smooth enough but then that a different situation to 3000 plus.  

I will drop off the scat from the carb for elimination of that issue, that's a great idea.  

I have oversized scat tube on the carb which I'm hoping will help with airflow but then I suppose that could be the cause.   

Regards, Clive  

       

  

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

 Sent: 16 January 2009 04:27

 To: jabiruengine-list(at)matronics.com

 Subject: RE: Full Thorttle Roughness Issue.  

Clive,  

   

I've had some positive results in fixing my roughness issue, but I'm still working out the details.  

   

Here's what I've got so far...  

   

I appear to have an air intake issue. Flying without the air intake system and just the carb open to the cowling area and the plane flies extremely smooth. This fixed the roughness for everything except the last 1/4" of throttle travel. Repitching the prop so I had an in flight max of ~3300 RPM fixed the last 1/4" of roughness. Before the pitch change, my max out in straight and level was 3000 RPM.  

   

I'm going to be installing various modified air intake setups over the next few weeks and will post my results.  

   

For what it's worth, after re-pitching and flying without the air intake system, the plane is amazing. I've gained about 5 to 10 MPH in speed and 300 feet per minute or more in climb and the engine is much smoother in all RPM ranges. I'm really excited about getting a good intake system designed  now that I'm seen the "other side" of this engine.  

   

Don  

   

       

From: owner-jabiruengine-list-server(at)matronics.com [mailto:owner-jabiruengine-list-server(at)matronics.com] On Behalf Of James, Clive R

 Sent: Thursday, January 15, 2009 15:22

 To: jabiruengine-list(at)matronics.com

 Subject: RE: Full Thorttle Roughness Issue.  

  

  

   

Don, I don't have a functioning EGT but what you describe with RPM and roughness is just what I'm experiencing on my Esqual with a 3300 Jabiru #1460. I've only got 15 hours on the engine and am chasing other issues for now so I'm very interested in the resolution. From what I've heard in the past and read about the Bing I'm in the main jet size change solution camp. Very interested in how you get on working the solution.   

   

Regards, Clive  

       

  

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

 Sent: 14 January 2009 16:19

 To: jabiruengine-list(at)matronics.com

 Subject: Full Thorttle Roughness Issue...  

I just wanted to take  moment and thank everyone that responded to my question both on-list and off (WOW - just absolutely amazing the response - THANK YOU!).  

   

From the various suggestions I decided that I needed to do a bit more investigation...  

   

During take-off AND WOT the EGTs on the right side of my engine are significantly higher than the left. The max difference being ~1400 versus 1100F. However, during cruise, everything tends to even out but now my left side (or at least cylinders #6 and #4) have higher EGTs than the right side in general (~1359  verus 1290).   

   

What is interesting is that my max RPM on take-off at WOT is ~2,850 and there is no roughness at all despite the same EGT profile. In contrast, when I do WOT in cruise the RPM maxes out at 3,000 and the roughness is pretty bad and starts at about 2900RPM and gets worse as the RPM increases. Also, pulling back so that the RPM is less than 2900 always gets rid of the roughness.  

   

So while the EGT profiles are essentially the same for both WOT situations, it would appear that when the engine is capable of going above 2900 RPM that the roughness occurs.   

   

Any thoughts?  

   

If interested, here are the two plot graphs for take-off and full power cruise:  

   

http://support.pcperfect.com/EGTs-TakeOff.pdf  

http://support.pcperfect.com/EGTs-WOT-Cruise.pdf  

   

Thanks!

 Don  

   

    	  Quote: 	
		    href="http://www.matronics.com/Navigator?JabiruEngine-List">http://www.matronics.com/Navigator?JabiruEngine-Listhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/c<O&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; href="http://www.matronics.com/Navigator?JabiruEngine-List" http://www.matronics.com/Navigator?JabiruEngine-List<O:PNBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; href="http://forums.matronics.com" http://forums.matronics.com        - List Contribution Web generous nbsp;           �            --> http://www.matronics.com/c= 	
  

No virus found in this incoming message.

 Checked by AVG - http://www.avg.com

 1/15/2009 07:46   	  Quote: 	
		     	
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No virus found in this incoming message.

 Checked by AVG - http://www.avg.com

 1/15/2009 07:46  

      [quote][b]

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