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Re: [Healeys] exhaust

To: healeys@autox.team.net
Subject: Re: [Healeys] exhaust
From: Oudesluys <coudesluijs@chello.nl>
Date: Fri, 15 Feb 2013 07:36:11 +0100
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There is a difference in working principal involved here. The original 
type mild steel exhaust dampers are usually of the reflective type, the 
exhaust gasses pass through a series of chambers of a predetermined 
size. These chambers are separated by barriers that are perforated or 
fitted with one or more tubes of varying diameter etc to enlarge the 
path the gasses have to go and to absorb certain frequencies. It is a 
fairly complicated matter. They can be rather restrictive.
Stainless Steel systems are usually straight through systems with much 
less restriction. The noise absorption is effected by ceramic wool or 
stainless steel wool with which the damper is filled that fits over the 
perforated exhaust pipe. Initially this gives a rather harsh sound but 
after a while the ceramic or ss wool gets coated with soot and partially 
gets blown out which will dull the sound but increases the sound level.
In general the reflective systems do a better job damping the noise but 
offer less performance.
There are also systems that are a combination of the two.
There are some stainless steel exhaust systems that are of the 
reflective type and made with the same gauge material. These sounds the 
same as the original mild steel exhausts.
Sound is not a question of stainless or mild steel, it is a question of 
construction.
As classic/vintage/antique not catalyst cars are only little used in 
general stainless steel is mostly used to prevent having to renew the 
exhaust system frequently because of rust from the inside out. The 
manufacturers design their ss systems with a certain sound in mind. 
Usually loud and dark.
If mild steel is used in combination with ceramic or (stainless) steel 
wool this will often cause rapid serious corrosion as non catalyst 
exhaust gasses produce acids together with condensation, especially on 
short runs where the exhaust has not been fully warmed up. The wool will 
absorb the moisture.

Kees Oudesluijs
NL


Op 15-2-2013 4:59, Bob Spidell schreef:
> We put a Falcon SS on our BN2.  It sounded tinny at first but has 
> mellowed with only a few dozen miles on it.
>
> Bob
>
>
> On 2/14/2013 7:22 PM, healeymanjim@hansencc.net wrote:
>> i put two falcon ss exhausts on a BJ7 and BN6 within a year.  both 
>> had to have the flange holes enlarged to get on the manifold studs.  
>> i have heard that problem is now solved, but be good to check.  had 
>> to do some rewelding on hanger straps as they were not lined up.  
>> like the sound on the BN6, but the BJ7 sounds kind of tinny.  of 
>> course, it's not my car, so what do i care.
>>
>>
>>
>>
>>
>> B
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