X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-d23.mx.aol.com ([205.188.139.137] verified) by logan.com (CommuniGate Pro SMTP 5.0.7) with ESMTP id 967370 for flyrotary@lancaironline.net; Sat, 04 Feb 2006 12:03:52 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.139.137; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-d23.mx.aol.com (mail_out_v38_r6.3.) id q.2cf.2c540cf (16930) for ; Sat, 4 Feb 2006 12:03:01 -0500 (EST) From: Lehanover@aol.com Message-ID: <2cf.2c540cf.31163845@aol.com> Date: Sat, 4 Feb 2006 12:03:01 EST Subject: Re: [FlyRotary] Re: Mazda mufflers To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1139072581" X-Mailer: 9.0 SE for Windows sub 5022 X-Spam-Flag: NO -------------------------------1139072581 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 2/4/2006 10:33:30 AM Eastern Standard Time, sladerj@bellsouth.net writes: Lynn, Does having a turbo make any difference to the ability of certain packing materials to survive? Dave's experience would seem to prove not. My new turbo has a 3 inch outlet. What if I inserted a 2 inch outlet pipe as shown in the attached? How many / how big on the holes? Sounds like a lot of drilling. :( Can the perforated pipe be bought? Regards, John The perforated material is just stainless sheet stock. It is rolled into tubes and welded to form the inner tube of the muffler. You can see through the length of the muffler. The high pressure pulse then partially leaks into the void between the outer diameter of the perf tube and the muffler shell. It then leaks back through the perf tube as the high pressure wave passes. The swarf filler just slows the induction on the up side, and slows the escape on the downside. So, the muffler trims the top (As seen on a scope) of the pulse, and that loss of energy drops the velocity below supersonic at the outlet. Like an accumulator for exhaust gasses. The carbon steel version of perf stock is available at Sears. OK for experimenting, but it won't last long. Any metals supply house will have a selection of the perf material, in a number of hole sizes and spacings. The NA housings have a stainless wedge cast into the exhaust liner to shape part of the pulse into a lower velocity, and that too reduces the amount of energy in the pulse. So, that a less complex muffler can be used. In all cases the total flow is still based on displacement X RPM, but the highest pressures are spread out in time to reduce the peak pressure. The turbo housings have no such wedge, because the turbine wheel mechanically removes so much energy that the flow leaves the hot side housing as subsonic flow, and much less complex muffling can be used. So I think the stuffing would do much better behind a turbo. AT 6,500 RPM, I suspect that an inner tube size as small as 2 1/2" would be big enough. My 4" ID perf tube muffler is good up to 9,600 + RPM. We don't use RPM that low (6,500) so I have no readings for that area. Lynn E. Hanover -------------------------------1139072581 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 2/4/2006 10:33:30 AM Eastern Standard Time,=20 sladerj@bellsouth.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Lynn,
Does having a=20= turbo=20 make any difference to the ability of certain packing materials to=20 survive?
Dave's experie= nce=20 would seem to prove not. 
 
My new turbo h= as a 3=20 inch outlet. What if I inserted a 2 inch outlet pipe as shown in the=20 attached?
How many / how= big on=20 the holes? Sounds like a lot of drilling. :(
Can the perfor= ated=20 pipe be bought?
Regards,
John
The perforated material is just stainless sheet stock. It is rolled int= o=20 tubes and welded to form the inner tube of the muffler. You can see through=20= the=20 length of the muffler.
 
The high pressure pulse then partially leaks into the void between the=20 outer diameter of the perf tube and the muffler shell. It then leaks back=20 through the perf tube as the high pressure wave passes. The swarf filler jus= t=20 slows the induction on the up side, and slows the escape on the downside.
 
So, the muffler trims the top (As seen on a scope) of the pulse, and th= at=20 loss of energy drops the velocity below supersonic at the outlet. Like an=20 accumulator for exhaust gasses.
 
The carbon steel version of perf stock is available at Sears. OK for=20 experimenting, but it won't last long. Any metals supply house will have a=20 selection of the perf material, in a number of hole sizes and spacings.
 
The NA housings have a stainless wedge cast into the exhaust liner to s= hape=20 part of the pulse into a lower velocity, and that too reduces the amount of=20 energy in the pulse. So, that a less complex muffler can be used. In all cas= es=20 the total flow is still based on displacement X RPM, but the highest pressur= es=20 are spread out in time to reduce the peak pressure.
 
The turbo housings have no such wedge, because the turbine wheel=20 mechanically removes so much energy that the flow leaves the hot side housin= g as=20 subsonic flow, and much less complex muffling can be used. So I think t= he=20 stuffing would do much better behind a turbo.
 
AT 6,500 RPM, I suspect that an inner tube size as small as 2 1/2" woul= d be=20 big enough.
 
My 4" ID perf tube muffler is good up to 9,600 + RPM. We don't use RPM=20= that=20 low (6,500) so I have no readings for that area.
 
Lynn E. Hanover
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