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Author Topic: exhaust wrap  (Read 8066 times)
cody
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« on: January 30, 2008, 09:40:34 PM »

In another thread the topic came up about an exhaust wrap, rather than hijack that thread I thought I'd start a new one, I'm interested in finding out more on this.  One thing that was brought up was that it would increase HP and MPG on a turboed DD, along with the added benefit of a cooler engine compartment, sounds like a win/win situation but it must have drawbacks too, whats the good and bad of this and cost involved, any idea's?
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JohnEd
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« Reply #1 on: January 30, 2008, 10:52:49 PM »

Cody,

The cost is the only down side and I don't know what the cost is.  I have heard it is not cheap but look at the pains we go thru to insulate the darlings.  How much is too expensive? 

I have seen this on Prevost 8V92 engines and I think it was installed by the manufacturer but don't know.

This was a long topic on a board that I frequent that deals with turbochargers.  They always do a test before and after and the wrap worked measurably well.  Real gains.

The logic of this is HEAT IS ENERGY.  If you cool the gas before it goes into the turbo the gas will shrink in volume, loose some of it velocity and can do less work.  I thought cooling the gas AFTER the turbo would not matter but it seems that cool gas is more dense and doesn't flow as well as hot gas.  I don't think it should matter all that much but they measure those pressures, compute the impact and then verify the results on a dyno.  The friggen "teenagers" are so smart it scares me and there doesn't seem to be all that much bull shXXt about them.  When the gas enters the muffler it expands and cools dramatically so they don't bother with the wrap after the muf inlet.  The tests and evals I read did not have efficiency as a subject but more power from a given ....is more efficiency and that is power and MPG.

I have read posts by bus owners that absolutely raved about how cool the engine compartment had become.  I don't think they were related to the mfr.  They wrap all these hot pipes in Navy ships and I understand the environment would be lethal without that feature.  Unfortunately they used asbestos till not to long ago.  This isn't cutting edge science but it is valid.

Hope you get more opinions,

John
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« Reply #2 on: January 31, 2008, 06:26:50 AM »

Cody,

We talked about this last summer.  Do a search here for wraps, heat wraps or something like that.   Believe you will find a coupld websites that sale the stuff.  It's not that expensive, for what it gets you.

If you can't find it,,,, let me know.

Bill
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TrevorH
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« Reply #3 on: January 31, 2008, 08:58:48 AM »

It looks like there is some affordable stuff on ebay but how much would one need for this size engine?
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1987 MCI 102A3 8V92TA 5 spd MT
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Tom Y
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« Reply #4 on: January 31, 2008, 09:11:03 AM »

Cody, I had mine custom made down in Texas. I sent the drawings and pics of what I had. Price seemed reasonable. I'll get the # if you are intrested. Tom Y
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Tom Yaegle
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« Reply #5 on: January 31, 2008, 11:02:58 AM »

Most Speed shops carry the stuff  comes in different widths.  I  own a Corvette and it is common to use it to prevent the ultimate burn out Grin   as well as Starter heat soak.  I also used it on my 6.5 Onan works great.  One line name is DEI
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skipn
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« Reply #6 on: January 31, 2008, 11:42:25 AM »

Cody,

    There has been volumes written about keeping the hot side of the turbo hot and the cold side cold.

    Some trivia.......
       There can be a 200 deg drop in temp from the head exhaust and the turbo exhaust.
        There can be > 100 deg rise in temp from the ambient temp to the head intake.
         (not including intercoolers at this point)

    Both situations reduce the effectiveness of the turbos ability to raise the air to fuel ratio.
    Diesel top ratio is 16:1 air/fuel. A raise in the intake temp has a noticeable effect.

   So wrapping the hot side helps keep the intake cooler and the exhausts warmer.
   Another trick that is being used is coolant cooled turbos.

   The only things I have read that is negative is moisture trapping causing exhaust pipe rusting.

    Of coarse any HP modifications can add more to the complexity.

  FWIW
     Mine is wrapped with a blanket style and does keep things a lot cooler. No scientific stats on that.
   Skip

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JohnEd
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« Reply #7 on: January 31, 2008, 11:43:33 AM »

Cody,

All the stuff I found on ebay and the net under "wet wrap" or "DEI" or "exhaust wrap" is NOT the correct stuff.  All that is is a fiberglass webbing that you wind on the ex pipe/header.  They say that reduces underhood temps by 70% and would a vendor lie?  Me thinks exaggerate most assuredly.  Imagine what the "REAL" stuff achieves.

The stuff I saw on the Prevost was at least 3/4 inch thick and had a fiber glass "mat" covering that was stitched along the longitudinal axis of the pipe.  Under the glass was a thick layer of fluffy ceramic cloth.  I don't know what they painted the glass with but it had a really firm feel.  The stuff had to be hand sewn/stitched to the pipe.  Owner said that the glass was cool to the touch so not much ex heat was getting in there.

It sounds like Tom got the "real" stuff if he had to send measurements and such and have it made for his engine.

Tom,

Can you send me the source info on the insulation you got....better yet post that data for Cody and me and others.  Please!

Thanks,

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
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« Reply #8 on: January 31, 2008, 11:47:57 AM »

From the research I just did, you should coat the wrap with a paint sealant that is designed for this.  To keep things from soaking into the wrap and keep it from falling apart.  I could easily be wrong so take this at face value
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« Reply #9 on: January 31, 2008, 11:48:20 AM »

Skip,

"Blanket" style?  Can you give us more info on that?  All the stuff I see advertised is a belt like webbing made of fiberglass.

Thanks,

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
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« Reply #10 on: January 31, 2008, 11:54:37 AM »

Trevor,

The stuff I saw WAS painted with something that made the fiberglass exterior hard/real firm.  You are right.  I never considered it being to keep the wrap from admitting water spray but that sure makes sense.  I not some of the stuff in kits has a couple cans of high temp paint included.  At least it looks like high temp paint.  It might be some sort of sealant though.  I would sure as heck paint my ex system before wrapping regardless.

Thanks for your post,

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
skipn
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« Reply #11 on: January 31, 2008, 11:59:47 AM »

 No problem...I'll take a picture tonight and post. There is a tag on it so hopefully
 I will be able to read the manufacture.

   It looks like a grey canvas type material sewn to fit the pipe. with a batting.

   Please remember I am running an inline not a V block Smiley So my set up is easier to
  do. (no cross over pipes and the like)

  There is one on this board that if memory serves used a type where
  you get wet, install and it dries in place (kind of like setting Plaster) and has a foil exterior.
   I still haven't been able to find a supplier for that or his post (picture) Smiley


 Skip
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skipn
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« Reply #12 on: January 31, 2008, 12:08:27 PM »


 One persons solution. (he did a nice job)

go look at
ChuckMC8 pictures page 5

 His web site is in his profile.


 Skip
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JohnEd
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« Reply #13 on: January 31, 2008, 12:37:27 PM »

Skip,

That is the stuff.  Looks like canvas....me thinks it is fiberglass with a painted on coating.  Under that "blanket" should be some sort of ceramic blanket material..."I think".

The foil with batting attached stuff is used to wrap the convoluted pipes on the input to a turbo.  It is on the net under heat wrap or exhaust wrap.  I know the real stuff got its name of "wet wrap" because you wet the stuff before application and the engine heat "fixed" it to that contour.

The comment about "WATER COOLED" turbo's isn't quite complete.  It should read "water cooled turbo bearings".  Just like oil cooled didn't mean you cooled the entire turbo, water cooled doesn't either.  Heat kills the bearings with "coke" build up from the oil so they added water to that so the things don't get as hot under load and you don't have to let the turbos cool before shutting down the engine.

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
skipn
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« Reply #14 on: January 31, 2008, 01:15:18 PM »


 John,

   You are correct I was sloppy in my water cooled comment.

  The main reason is to keep the bearing cool (relative term)
 I would also submit to you the concept that by keeping the
 bearing cool one also sets up a minor thermal barrier to absorb
 some of the heat that normally would be transfered through the
 cartridge to the intake.

 in short every little bit helps when dealing with 1100+ deg F.
 
Dejavu I think we have been here before Smiley

Thanks
Skip
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