X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-d03.mx.aol.com ([205.188.157.35] verified) by logan.com (CommuniGate Pro SMTP 5.1c.5) with ESMTP id 1453647 for flyrotary@lancaironline.net; Tue, 10 Oct 2006 11:10:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.35; envelope-from=WRJJRS@aol.com Received: from WRJJRS@aol.com by imo-d03.mx.aol.com (mail_out_v38_r7.6.) id q.582.5290828 (49387) for ; Tue, 10 Oct 2006 11:09:42 -0400 (EDT) Received: from FWM-R06 (fwm-r06.webmail.aol.com [152.163.211.134]) by ciaaol-d07.mail.aol.com (v112_r1.5) with ESMTP id MAILCIAAOLD073-c0eb452bb7b4ed; Tue, 10 Oct 2006 11:09:40 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Exhaust Update Date: Tue, 10 Oct 2006 11:09:40 -0400 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: wrjjrs@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MailBlocks_8C8BA953E537428_804_9106_FWM-R06.sysops.aol.com" X-Mailer: AOL WebMail 20458 Received: from 65.161.241.3 by FWM-R06.sysops.aol.com (152.163.211.134) with HTTP (WebMailUI); Tue, 10 Oct 2006 11:09:40 -0400 Message-Id: <8C8BA953E55D67D-804-4C40@FWM-R06.sysops.aol.com> X-AOL-IP: 152.163.211.134 X-Spam-Flag: NO ----------MailBlocks_8C8BA953E537428_804_9106_FWM-R06.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" FYI Folks, comercial exhaust headers are welded on the inside, and tacked on the outside. Motorcycles have always been welded in the inside or rolled inside a flange. For performance btw it is better for the exit pipe to be slightly larger than the exhaust port. Bill Jepson -----Original Message----- From: finn.lassen@verizon.net To: flyrotary@lancaironline.net Sent: Tue, 10 Oct 2006 7:25 AM Subject: [FlyRotary] Re: Exhaust Update One possible advantage of welding them on the inside could be it may protect the edges of the pipe from those devastating exhaust pulses. My last exhaust had the pipes sticking through the flanges maybe 1/2" into the port. It was possible to shape the 0.035 SS into an oval snugly fitting into the oval port. In the course of 100's of hours the edges of the pipe slowly got eaten away. Another reason is strees relief. The weakest point is often just next to a weld. If the pipe fits snugly through the flange the pipe is mechanically supported by the flange and not just hanging in the weld. But as other posters have commented, probably not an issue as most commercial systems are welded on the outside. Probably depends on thickness of material and how well the pipe is supported (also taking into consideration vibration and resonance frequencies which brings us back to looking at it with a strobelight as run run the engine and prop through its entire RPM range). Finn kenpowell@comcast.net wrote: > Hi Joe, > Those are really great results. I would love to know the HP > increase. Just a heads up - it looks like your new "header flange to > pipe" (picture 5) was welded on the outside. I think that 'acceptable > practices' state that there should only be a tack weld on the outside > and the actual structural weld should be on the inside. What does > everyone else say? In any event be sure to keep an eye on the welds. > > Ken Powell > Bryant, Arkansas > 501-847-4721 > C150 / RV-4 under construction > -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ________________________________________________________________________ Check out the new AOL. Most comprehensive set of free safety and security tools, free access to millions of high-quality videos from across the web, free AOL Mail and more. ----------MailBlocks_8C8BA953E537428_804_9106_FWM-R06.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii"

FYI Folks, comercial exhaust headers are welded on the inside, and tacked on the outside. Motorcycles have always been welded in the inside or rolled inside a flange. For performance btw it is better for the exit pipe to be slightly larger than the exhaust port.

Bill Jepson

-----Original Message-----
From: finn.lassen@verizon.net
To: flyrotary@lancaironline.net
Sent: Tue, 10 Oct 2006 7:25 AM
Subject: [FlyRotary] Re: Exhaust Update

One possible advantage of welding them on the inside could be it may protect the edges of the pipe from those devastating exhaust pulses. My last exhaust had the pipes sticking through the flanges maybe 1/2" into the port. It was possible to shape the 0.035 SS into an oval snugly fitting into the oval port. In the course of 100's of hours the edges of the pipe slowly got eaten away.

Another reason is strees relief. The weakest point is often just next to a weld. If the pipe fits snugly through the flange the pipe is mechanically supported by the flange and not just hanging in the weld.

But as other posters have commented, probably not an issue as most commercial systems are welded on the outside.
Probably depends on thickness of material and how well the pipe is supported (also taking into consideration vibration and resonance frequencies which brings us back to looking at it with a strobelight as run run the engine and prop through its entire RPM range).

Finn

kenpowell@comcast.net wrote:

> Hi Joe,
> Those are really great results. I would love to know the HP > increase. Just a heads up - it looks like your new "header flange to > pipe" (picture 5) was welded on the outside. I think that 'acceptable > practices' state that there should only be a tack weld on the outside > and the actual structural weld should be on the inside. What does > everyone else say? In any event be sure to keep an eye on the welds.
>
> Ken Powell
> Bryant, Arkansas
> 501-847-4721
> C150 / RV-4 under construction
>

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Homepage: http://www.flyrotary.com/
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