[Diy_efi] Can constant WOT operation destroy a muffler?

[John Gross]

>From my experience in endurance road racing (I work in the Rolex Series),
extended operation at or near WOT can and will destroy a muffler if this
occurs for long durations.  (with our stuff, it's not uncommon to repack the
muffler every race).  1/4 mile stuff does not heat saturate the exhaust
system enough to do it.  Having a cat in there, if the cal is producing very
rich mixtures at WOT, can increase the EGT downstream of the cat enough to
heat saturate the muffler.  Typically mufflers are more resilient to this,
though it does depend on the proximity of the mufflers to the cat, how rich
the fuel mixture is, and how good your mufflers are.  Crappy mufflers won't
take it well, but good stainless mufflers and the like might.  Better
solution.... re-gear the Jeep so you don't work the engine so hard.  I
assume you didn't do that when the tires and lift kit went on.  If you do,
your engine and trans will last a whole lot longer, you'll get much better
fuel mileage, and the thing will accelerate MUCH better.

John 

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
Behalf Of Jim Butterfield
Sent: Wednesday, June 14, 2006 11:29 PM
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] Can constant WOT operation destroy a muffler?

Hello Andy, 
  There are a few of us in our club that have cars only for racing... and
that means WOT for `1/4 strip... none of our mufflers wear out... have your
good supports on the exhaust system???
   
  jim
  

Andy Harvilla <higrafey at gmail.com> wrote:
  Hey guys,

I have an unusual "problem" (if you can even call it that) with my 
Jeep Wrangler that I think can be attributed to near-constant WOT 
operation. Every year, no joke, I have to install a new muffler on 
my Jeep because the old one cracks underneath in exactly the same 
spot. Even after only a few hundred miles of use, you can see the 
metal casing begin to warp and swell, presumably from high heat.

It occurred to me that this might be happening because of the way I 
drive the vehicle. The little four-cylinder engine has no power 
(considering the 33-inch tires it's pushing) and I'm nearly always at 
full-throttle just to get the sucker to move... going up hills, 
highway driving, etc. Do you think the computer is enabling WOT mode 
and richening up the mixture, which in turn heats up the catalytic 
converter and slowly melts the muffler? There's always a constant 
rich smell and the tailpipe is usually black. I had to install a cat 
due to inspection reasons (the previous owner hollowed it out), but 
before then, I never had an issue with mufflers blowing out. It 
seems like the converter might be the root of the problem. One of my 
friends owns a Wrangler, drives it the same way, and also replaces 
mufflers annually. We always thought it was "just a Jeep thing"... :-)

Andy
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