question regarding header & tuned pipe

[Gray E Fowler]

Without actually being privy to what these guys are using resin wise, but 
experienced in identifying cured resins, I would venture to say the the ES 
pipe is an aromatic amine cured epoxy that is made by Shell Chemical , 
8500 series. It is a liquid that cures at a temperature about 200-250 F 
then can be post cured to give a glass transition temperature (Tg) of 
about 350F.  This means at 350F the resin goes from the hard glassy state 
to a more "rubbery" state. The Tg is usually when there is little to no 
structural capability, but these temperatures do not necessarily damage 
the resin. When over exposed to temperature above the Tg like the 425-450F 
exhaust, the resin will break down.   The Bolly appears to be a 
Bismaleimide resin which is a room temp semisolid resin that has a Tg of 
425-450 hence better header exhaust resistance.  The leaking of the pipe 
is most likely a result of the wet-layup manufacturing method used, 
leaving pinholes. Bolly's also have a kevlar outer layer which absorbs 
water which gases off during cure creating pinholes. 
And then there is the chance I am guessing wrong......





Gray Fowler
Principal Chemical Engineer
Composites Engineering




s.vannostrand at kodak.com
Sent by: discussion-request at nsrca.org
03/25/2003 12:47 PM
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        Subject:        Re: question regarding header & tuned pipe



Bolly mufflers use a very different kind of resin that is more temp 
resistent than the ES pipes.  It will become brittle over time, but will 
not ablate.  Bolly's also eventually leak like a seive over their length 
eventually. 

--Lance 




Ron Lockhart <ronlock at comcast.net> 
Sent by: discussion-request at nsrca.org 
03/25/2003 10:11 AM 
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        To:        discussion at nsrca.org 
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        Subject:        Re: question regarding header & tuned pipe



Lance,

Would you know, is the end of the pipe being exposed to exhaust 
gas a concern with the Bolly pipes & mufflers?

TIA   Ron Lockhart

----- Original Message -----
From: s.vannostrand at kodak.com
Date: Tuesday, March 25, 2003 10:52 am
Subject: Re: question regarding header & tuned pipe

> Every change in backpressure, due to the expansion chamber or 
> header change will cause a wave reflection, however, the effects of 
> necking down from 7/8 to the approx 3/4" OS pipe will not be much. 
The bigger problem is that if the pipe is composite (CF) you will 
ablate the pipe input and ruin the pipe.  I've seen 3 of these for 
repair.  The hot exhaust gasses can not be allowed to contact the end 
of the fibers and resin for most resins.  ES pipes fail in this 
fashion.  Some people have been successful in using a squishy coupler 
(like the Macs grey) but this is not a reliable setup for most people. 
> 
> The Mintor carbon fiber pipe (I have a N.I B. one for sale for 
> $160 including shipping) uses an aluminum inlet to prevent this.  I 
> also have a Macs to OS adapter made from aluminum for $12.
> 
> -Lance


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