X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.122] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3839044 for flyrotary@lancaironline.net; Sun, 06 Sep 2009 11:57:26 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.122; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta01.mail.rr.com with ESMTP id <20090906155651519.CVQV5638@cdptpa-omta01.mail.rr.com> for ; Sun, 6 Sep 2009 15:56:51 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: DNA muffler Date: Sun, 6 Sep 2009 11:55:30 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0022_01CA2EE8.EF3133F0" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: Acou7+W+avCwXe3XSuO5xyMlE+e1KgAFyNoQ In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20090906155651519.CVQV5638@cdptpa-omta01.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0022_01CA2EE8.EF3133F0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Well, I can always be wrong, Bill. However, more air mass flow at the same rpm (due to "theoretical" better flow, i.e. Better volumetric efficiency) would mean the EC2 would see higher manifold pressure and should respond by enrichening the mixture to match - I mean that is what the EC does- match fuel flow to manifold pressure. Now you would think that if it matched the higher manifold pressure accurately then while more fuel would be flowing - the air/fuel ratio (which is what we are looking at on our indicator) should theoretically remain the same. Could be the EC "over compensated" ? Perhaps another way of looking at is with the old muffler which gave a certain manifold pressure at rpm X would then point to the corresponding manifold pressure bin in the EC2 MCT. Now if at the same rpm with the new muffler the airflow mass flow is greater - then the manifold pressure at X rpm will be corresponding greater. Since the EC2/3 is using manifold pressure to point to the correct bin - it is now pointing a couple of bins higher in the map. Normally the higher you are in the map the more fuel is signaled to flow. So Mike would then have to "re-adjust" the MCT table to match the new volumetric efficiency increase. Now if the new muffler was producing more back pressure then the airflow would be lower for the same RPM or the Volumetric efficiency would be somewhat worst than the with the old muffler. So if the lower air mass flow corresponds to a lower manifold pressure then the EC2 should be point a couple of bins lower in the MCT which normally would signal less fuel is required and injected to match the lower air flow. Or at least that is my take on it. Perhaps Tracy is loafing around today {:>) and will come on line the real explanation. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry Sent: Sunday, September 06, 2009 8:45 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: DNA muffler Ed, We are on opposite sides of this possibility. Seems that if there were more air allowed, the mixture would lean, not richen. This is exactly what I was thinking when I suggested that the muffler might cause more back pressure, lower the air flow, and cause richness.??? What I may be missing is just what the EC-2/3 would do if it saw a certain condition. Explain, please. Bill B _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson Sent: Sunday, September 06, 2009 8:20 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: DNA muffler Hi Mike, Interesting reaction of engine to your DNA muffler. A possible explanation for richer across the board. It appears that the DNA muffler may offer less back pressure to the engine meaning you get more air into the engine at any given rpm. That could increase your manifold pressure and drive the EC2 to enrichen the mixture to compensate. The reason the top end rpm may not change is that at that point there is some other restriction such as the intake, TB, etc that may come into play. Just a theory of course. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills Sent: Saturday, September 05, 2009 11:47 PM To: Rotary motors in aircraft Subject: [FlyRotary] DNA muffler Received my DNA muffler this past week and got it installed and running. Havent flown it yet, but have done some taxi and full power runups. So far I'm a little disappointed. It doesnt appear to be any quieter than my home made muffler. I'll reserve judgement until I actually fly it, but from the cockpit the noise level seems the same, and my buddy standing about 50 ' away said he thought the noise level was the same. One thing not the same - the muffler screwed up my tuning. It appears to be considerably richer now all across the RPM range. And the big bog at the staging point that took me so long to tune out is back with a vengeance. Oddly, in spite of the tune issues it still appears to reach the same static RPM as previously. Looks like the solution for me is going to be the high $ headset and the rest of the world is just going to have to live with it. Mike Wills RV-4 N144MW __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_0022_01CA2EE8.EF3133F0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Well, I can always be wrong, = Bill.  However, more air mass flow at the same rpm (due to = “theoretical” better flow, i.e. Better volumetric efficiency) would mean the EC2 would = see higher manifold pressure and should respond by enrichening the mixture = to match – I mean that is what the EC does- match fuel flow to manifold pressure.  Now you would think that if it matched the higher = manifold pressure accurately then while more fuel would be flowing – the = air/fuel ratio (which is what we are looking at on our indicator) should = theoretically remain the same.  Could be the EC “over compensated” ? =

 

Perhaps another way of looking at = is with the old muffler which gave a certain manifold pressure at rpm X would = then point to the corresponding manifold pressure bin in the EC2 MCT.  = Now if at the same rpm with the new muffler the airflow mass flow is greater - = then the manifold pressure at X rpm will be corresponding greater.  = Since the EC2/3 is using manifold pressure to point to the correct bin – it = is now pointing a couple of bins higher in the map.  Normally the higher = you are in the map the more fuel is signaled to flow.  So Mike would then = have to “re-adjust” the MCT table to match the new volumetric efficiency = increase.

 

Now if the new muffler was = producing more back pressure then the airflow would be lower for the same RPM or the Volumetric efficiency would be somewhat worst than the with the old muffler.  So if the lower air mass flow corresponds to a lower = manifold pressure then the EC2 should be point a couple of bins lower in the MCT = which normally would signal less fuel is required and injected to match the lower air = flow.

 

Or at least that is my take on = it.

 

Perhaps Tracy is loafing around today = {:>) and will come on line the real explanation.

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry
Sent: Sunday, September = 06, 2009 8:45 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = DNA muffler

 

Ed,

We are on opposite sides of this possibility.  Seems that = if there were more air allowed, the mixture would lean, not richen.  This is exactly what I was thinking when I suggested that the muffler might = cause more back pressure, lower the air flow, and cause = richness.???

 

What I may be missing is just what the EC-2/3 would do if it saw = a certain condition.  Explain, please.

 

Bill B 

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Sunday, September = 06, 2009 8:20 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = DNA muffler

Hi = Mike,

 

Interesting reaction of engine to = your DNA muffler.  A possible explanation for richer across the board.  = It appears that the DNA muffler may offer less back pressure to the engine = meaning you get more air into the engine at any given rpm.  That could = increase your manifold pressure and drive the EC2 to enrichen the mixture to compensate.  The reason the top end rpm may not change is that at = that point there is some other restriction such as the intake, TB, etc that = may come into play.  Just a theory of course.

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Wills
Sent: Saturday, September = 05, 2009 11:47 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] DNA = muffler

 

Received my DNA muffler this past week and got it = installed and running. Havent flown it yet, but have done some taxi and full power runups. So far I'm a little disappointed. It doesnt appear to be any = quieter than my home made muffler. I'll reserve judgement until I actually fly = it, but from the cockpit the noise level seems the same, and my buddy standing = about 50 ' away said he thought the noise level was the = same.

 

 One thing not the same - the muffler screwed up = my tuning. It appears to be considerably richer now all across the RPM = range. And the big bog at the staging point that took me so long to tune out is = back with a vengeance. Oddly, in spite of the tune issues it still appears to = reach the same static RPM as previously.

 

 Looks like the solution for me is going to be = the high $ headset and the rest of the world is just going to have to live with = it.

 

Mike Wills

RV-4 N144MW



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

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