REFLECTOR:Re: Exhaust system

[Scott]

I have an updraft IO360, straight back SS exhaust.

I tried it with and with out tape.  I would say the tape may, and I am 
stretching here,  may have reduced my CHT's by 5 degrees.  I took um 
off.  I want to be able to see my exhaust pipes when I'm poking around 
under the cowling and I've heard they do shorten a systems life, and at 
$800 a pop I don;t want to shorten that one to much.

I'd say I got my CHT's down by being extremely anal about sealing up the 
cowling and running LOP.

I have a hard time keeping them above 300 degrees now that's its winter.

Scott

At 10:25 PM 12/9/2003, you wrote:
><... You are putting on the same exhaust system that you have already 
>proven is unsafe
>....>
>The short answer is no.  This is the part I was a little reluctant to 
>share, absent a
>direct question, but it appears I can't get out of it so I might as well 
>get into it
>.... :o(
>
>When the airplane came my way it had kind of raggedy looking steel 
>exhaust.  Last year
>at annual I found cracks so I replaced it with SS unit.  Flange just 
>barely did fit
>and pipe end fouled the exhaust nipple in the lower cowl so I had to bend 
>it.  Bending
>SS pipes is not a trivial matter.  Anyway, this year I got snatched up 
>short at Rough
>River about flying around (nearly) full rich because CHTs went up way too 
>high if I
>leaned the engine, so I redid most of the baffling and sealed everything 
>up including
>the exhaust pipes near the nipples.  CHTs were still way high, so I 
>inspected the
>pipes and wrapped them with exhaust tape (the asbestos looking stuff you 
>get at hot
>rod shops) so I wouldn't be pre-heating the cooling air so much in the 
>plenum.  It
>worked marginally and I then solved my CHT problem for the most part 
>another way
>(that's irrelevant so I needn't share :o).
>
>Anyway, taping the pipes is going to make them retain a lot of the heat 
>that used to
>conduct out into the plenum, so the pipes will be a good bit hotter than 
>without wraps
>and will not live so long.  Figured I'd pull the wrap at annual MINIMUM 
>and check for
>cracks and hints of cracks.  Stuff was only on there less than 10 hrs when 
>pipe broke
>off, and there were other nearly and minor cracks on the part of the pipe that
>remained.  The pipe on there now is a steel unit that I am going to 
>exchange with
>Valerie for the SS unit when she gets one in.  I will then be able to do a 
>good
>comparison of CHTs with and without wraps.  If they aren't dramatically 
>beneficial I
>will pull the wrap off the port side pipe.  If they are, I will downdraft 
>the f%*^($
>airplane.
>
>So now you've heard "... the rest of the story ..." :o)  ... Jim S.
>
>KeithHallsten wrote:
>
> > Jim,
> >
> > I'm happy to hear that your recent exhaust failure didn't result in a more
> > serious incident, but. . .
> >
> > You are putting on the same exhaust system that you have already proven is
> > unsafe?!?!  Say it isn't so!  It seems to me you should be doing some
> > serious thinking about designing a more reliable exhaust system.  You might
> > start with talking to Clint Anderson at Custom Aircraft Parts (see
> > http://www.customaircraft.com/).  He built a custom exhaust for my IO-540
> > that I believe will be much less prone to shedding the tailpipe through the
> > prop than the Velocity exhaust, for about the same price.  The life you 
> save
> > may be you own!
> >
> > Keith
>
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