X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao102.cox.net ([68.230.241.44] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3839029 for flyrotary@lancaironline.net; Sun, 06 Sep 2009 11:18:59 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.44; envelope-from=rv-4mike@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao102.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20090906151823.VEVA12000.fed1rmmtao102.cox.net@fed1rmimpo01.cox.net> for ; Sun, 6 Sep 2009 11:18:23 -0400 Received: from wills ([68.105.80.138]) by fed1rmimpo01.cox.net with bizsmtp id dTJL1c0032z3ATG03TJNQi; Sun, 06 Sep 2009 11:18:23 -0400 X-VR-Score: 0.00 X-Authority-Analysis: v=1.0 c=1 a=kviXuzpPAAAA:8 a=XDditBqTDVtVVITLGjYA:9 a=_3CnO51duulKU8fAWigA:7 a=qTNVTBl5ZJp_m47HnNCaTgNRjnsA:4 a=4vB-4DCPJfMA:10 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=Vub2CtzEpBOy0XZ31xcA:9 a=Q4JTzybetkuJXkhFZTAA:7 a=4_NsxGgw8xjhvyVLcefy6Lqs2BYA:4 a=MSl-tDqOz04A:10 a=EzXvWhQp4_cA:10 X-CM-Score: 0.00 Message-ID: <96E81FDB281F400B979861EBBE1FE4AF@wills> From: "Mike Wills" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: DNA muffler Date: Sun, 6 Sep 2009 08:18:20 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0016_01CA2ECA.983B3910" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0016_01CA2ECA.983B3910 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mark/Ed/Bill, I did not buy the same DNA that you bought. Mine is a truck muffler with = 2 1/4 inlets and outlets. I figured the larger body/volume of the truck = mufflers would help quiet things down. And the truck series mufflers are = almost identical in dimension to the muffler I started with. At this = point I'm hesitant to choke the thing down anymore by putting a reducer = on the outlet, but I guess there really isnt anything to loose. Except = HP. I was thinking along the same lines as Bill - that the DNA is more = restrictive resulting in richer mixtures at equivalent MAP. My home made = muffler was a copy of the Moroso spiral flow mufflers, but with a larger = center tube. With my home made muffler I can look all the way through it = so the DNA is clearly more restrictive. Which is why I'm surprised it = didnt work better. The DNA sure looks better than my home made muffler. Weld quality is = great. Time will tell how it holds up. The home made muffler was Inconel = so I expect it would be more durable in the long run. The point of something else in the airflow path limiting HP is a good = point. One of things I've noticed is that I reach max power long before = I reach max throttle. Since I'm making enough power for good performance = I wasnt too worried about this, but I am curious. Once I reach about 3/4 = throttle I'm maxed out - the last 1/4 doesnt do anything. Mike Wills RV-4 N144MW ----- Original Message -----=20 From: Mark Steitle=20 To: Rotary motors in aircraft=20 Sent: Sunday, September 06, 2009 5:55 AM Subject: [FlyRotary] Re: DNA muffler Mike,=20 I had the same impression of the DNA muffler. Then I remembered what = Tracy said about big pipes being louder than smaller pipes. So, I = ordered a tapered transition piece from Burns Stainless, bringing it = down from 3" to 2 1/4". That helped reduce the noise considerably and I = couldn't detect any reduction in hp. Or, you could spring for a pair of = those $800 headsets, or you could do both. =20 Mark S. On Sat, Sep 5, 2009 at 10:46 PM, Mike Wills wrote: 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 ------=_NextPart_000_0016_01CA2ECA.983B3910 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Mark/Ed/Bill,
 
I did not buy the same DNA that you = bought. Mine is=20 a truck muffler with 2 1/4 inlets and outlets. I figured the larger = body/volume=20 of the truck mufflers would help quiet things down. And the truck series = mufflers are almost identical in dimension to the muffler I started = with. At=20 this point I'm hesitant to choke the thing down anymore by putting a = reducer on=20 the outlet, but I guess there really isnt anything to loose. Except=20 HP.
 
I was thinking along the same lines as = Bill - that=20 the DNA is more restrictive resulting in richer mixtures at equivalent = MAP. My=20 home made muffler was a copy of the Moroso spiral flow mufflers, but = with a=20 larger center tube. With my home made muffler I can look all the way = through it=20 so the DNA is clearly more restrictive. Which is why I'm surprised it = didnt work=20 better.
 
The DNA sure looks better than my home = made=20 muffler. Weld quality is great. Time will tell how it holds up. The home = made=20 muffler was Inconel so I expect it would be more durable in the long=20 run.
 
The point of something else in the = airflow path=20 limiting HP is a good point. One of things I've noticed is that I reach = max=20 power long before I reach max throttle. Since I'm making enough power = for good=20 performance I wasnt too worried about this, but I am curious. Once I = reach about=20 3/4 throttle I'm maxed out - the last 1/4 doesnt do = anything.
 
Mike Wills
RV-4 N144MW
----- Original Message -----
From:=20 Mark = Steitle=20
Sent: Sunday, September 06, = 2009 5:55=20 AM
Subject: [FlyRotary] Re: DNA=20 muffler

Mike,
 
I had the same impression of the DNA muffler.  Then I = remembered=20 what Tracy said about big pipes being louder than smaller = pipes. =20 So, I ordered a tapered transition piece from Burns Stainless, = bringing it=20 down from 3" to 2 1/4".  That helped reduce the = noise considerably=20 and I couldn't detect any reduction in hp.  Or, you could spring = for=20 a pair of those $800 headsets, or you could do both.  =
 
Mark S.
On Sat, Sep 5, 2009 at 10:46 PM, Mike Wills = <rv-4mike@cox.net>=20 wrote:
Received my DNA muffler this past = week and got=20 it installed and running. Havent flown it yet, but have done some = taxi and=20 full power runups. So far I'm a little disappointed. It doesnt = appear to be=20 any quieter than my home made muffler. I'll reserve judgement until = I=20 actually fly it, but from the cockpit the noise level seems the = same, and my=20 buddy standing about 50 ' away said he thought the noise level was = the=20 same.
 
 One thing not the same - the = muffler=20 screwed up my tuning. It appears to be considerably richer now all = across=20 the RPM range. And the big bog at the staging point that took me so = long to=20 tune out is back with a vengeance. Oddly, in spite of the tune = issues it=20 still appears to reach the same static RPM as = previously.
 
 Looks like the solution for = me is going=20 to be the high $ headset and the rest of the world is just going to = have to=20 live with it.
 
Mike Wills
RV-4=20 = N144MW

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