Additional Factors Re: <VV> Re: [fastvair] Wrapping turbo pipes

[FrankCB at aol.com]

    I can confirm that the stock turbo exhaust crossover piping will not hold 
up very long to wrapping.  Mine lasted just a few months of driving to work 
and back every day before it disintegrated at the upward elbow.  The chief 
metallurgist at work said it was due to "overtemperature" meaning, of course, the 
steel couldn't withstand the higher temps brought about by the insulation.  
While it lasted, however, the boost "came up" more quickly (turbo lag was 
reduced) and the full load boost on the same long hill went from 8 psig to 10 psig 
(on an after-market gauge that could read to the nearest 1/2 psig).
    Another disadvantage I noticed when I replaced the pipe, was that BOTH 
flanges were loose at the ends of the exhaust manifolds.  This leads me to 
believe the considerably higher temps from the wrapping caused greater than stock 
expansion of the crossover piping putting undue stress on the flange bolts 
causing them to loosen.  So if you DO wrap the crossover, I'd suggest first 
installing an expansion joint (maybe a bellows) to avoid the "untightening" of the 
manifold flanges resulting in subsequent loss of boost pressure.
    Since the turboexpander "wheel" recovers energy from both the pressure 
AND the temperature of the exhaust, insulating the piping to keep the temp up is 
advantageous for street driving as well as track events where the throttle is 
not continually "flat on the floor."
    If you find anybody willing to make turbo exhaust piping out of SS, let 
me know so I can sign up for a set.  I wonder just how many of us would have to 
sign up (and deposit $$$) to get Borla to fabricate these out of SS.
    Frank "likes turbos hot and drivers cool" Burkhard  

In a message dated 8/12/05 7:36:27 PM Eastern Daylight Time, 
ral1963 at comcast.net writes:
>From a post that you posted in the archives I believe that 310 Stainless
was the pipe of choice after some debate...

Does anyone know of anyone who is willing to make a stainless crossover
and turbo pipe?

Rick Loving

<SNIP>
Subject: <VV> Re: [fastvair] Wrapping turbo pipes

The issue isn't one of salt corrosion or moisture really... The basic 
elcheapo mild steel metallurgy will not hold up to the temperature.  I 
agree with Mike Mann. Coat the pipes, but do not wrap them (unless this 
is an all-out track car where you are willing to replace pipes very 
regularly).   The aluminization is worthless for protection for the 
temperatures we are talking about!  Matt was spot on with regard to SS 
exhaust.  If you want a super insulated exhaust to last, have it custom 
made out of 300 series SS.

Jim Burkhard