From: "David Leonard" <flyrotary@lancaironline.net>
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Date: Fri, 20 Jan 2017 18:22:35 -0800
Message-ID: <CAOFHbnrHaicL9NF9M=TC4tdiy2Dfy8x6=pYT9opMJ9PxiY8aoA@mail.gmail.com>
Subject: Re: [FlyRotary] Re: exhaust wraps and blankets
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Todd,

I have used both wraps and ceramic coating.  I will not use wraps
anymore because of the reasons Lynn mentioned.  The coating sometimes
flake off, but most of it is there years later.  if you need to
modify, then it leaves a small uncoated area but that is no big deal.
The stock heat shields over the turbo hold up OK except for the
attachment area..  My very poor TIG skills were good enough to fix
that.

I use heat shields over any hoses, wires or engine mount that are
seeing the radiant heat.

Otherwise, the air flow that has passed through the oil, water, and
intercoolers is still plenty cool to keep temps under the cowl in a
tolerable range.

BTW, even the best wraps only last a couple hundred hours before they
start falling apart and make a perpetual mess.  Corrosion underneath
them is evident in short order.

Dave Leonard

On 1/20/17, William Jepson <flyrotary@lancaironline.net> wrote:
> David,
> I really like the coating rather than the heat wraps. The wraps do work,
> but as Lynn said the pipes frequently corrode inside them. They seem to
> grab the moisture on cool down or just let the inside oxidize due to the
> contained high temperature. I have used both and the Jet-Hot seemed to wo=
rk
> just as well without the oxidation problem. One other thing is the wraps
> add significant size to the pipes which can be a problem when routing too=
.
> Bill Jepson
>
> On Fri, Jan 20, 2017 at 2:44 PM, hoursaway1 <flyrotary@lancaironline.net>
> wrote:
>
>> Bill, that is the sys on our 13B RV6A Rotary now, inside/outside
>> coatings,
>> down to the Y pipe, so far, so good.  David R. Cook  RV6A Rotary
>>
>> ------------------------------
>> *From: *"William Jepson" <flyrotary@lancaironline.net>
>> *To: *"Rotary motors in aircraft" <flyrotary@lancaironline.net>
>> *Sent: *Friday, January 20, 2017 2:13:41 PM
>> *Subject: *[FlyRotary] Re: exhaust wraps and blankets
>>
>> Lynn, EtAll,
>> I want to mention the alternative to heat wraps, ceramic coatings. I hav=
e
>> used Jet-Hot on headers for insulation and performance. Early Jet-Hot
>> didn't have a super high temp coating that would stand up to rotary
>> exhaust
>> temperatures. They have had an 1800=C2=B0F+ material for some time now. =
They
>> needed to have a coating that would stand up to turbo header
>> temperatures.
>> They have a service where they apply to the inside and outside of the
>> pipes. There is a very minor smoothing effect that even help HP. The
>> insinuative effect is as good or better than most heat wraps, and the
>> pipes
>> look great too. I have used them for pipes on racing motorcycles that
>> have
>> tight fairings. I measured a 30=C2=B0 difference inside my fairing with =
no
>> other
>> changes using color change tape, but I think is was even better than tha=
t
>> in terms of radiated heat. I had a battery located in the fairing mounte=
d
>> low in front of the headers. This no longer was showing bubbling and
>> melting effects, and survived a 4 hour endurance race as a total loss
>> system. I don't work for those guys, and wasn't sponsored by them either=
.
>> I
>> highly recommend them.
>> Bill Jepson
>>
>> On Fri, Jan 20, 2017 at 10:07 AM, Lehanover <flyrotary@lancaironline.net=
>
>> wrote:
>>
>>> The good news is: Heat wrap tape works great. Amazing drop in temps
>>> around the engine.
>>>
>>> The bad news is: Carbon steel headers, even in .140" wall turn to dust
>>> in
>>> one racing season.
>>> Literally you can crush the header pipes with one hand. The outside
>>> radius of bent tubes is thinner and will  fail sooner.That bright orang=
e
>>> header you see in tapes of dyno runs is exactly what your heat taped
>>> header
>>> looks like. How strong is bright orange steel? Even stainless?   Steel
>>> under stress fails sooner.  Each down pipe should be free to twist and
>>> squirm a bit as it heats and cools. Only stainless down tubes and only
>>> thick wall stainless at that. If you wrap the whole thing the exiting
>>> exhaust gasses will be close the EGT readings on the gage. Will your ca=
r
>>> muffler hold up to 1600 degrees. If some heat tape falls off along thos=
e
>>> pipes will the bright orange pipe damage anything important?
>>>
>>> Then a collector to take the two or three tubes (all exactly the same
>>> length) in and then the beginning of the exhaust system. Collector
>>> attaches
>>> with stiff springs the down pipes. A strap fail safe in case a spring
>>> fails. Two strands of safety wire through the spring loosely in case th=
e
>>> spring fails (they like to sing along with the engine) you know and a
>>> piece
>>> of spring will find a place to get stuck that will be the least helpful=
.
>>> The collector is supported  loosely by a bracket that moves with the
>>> engine.
>>>
>>> Then a slip joint or flex joint of some kind to account for the engine
>>> moving about with power changes. Then the exhaust system, mufflers and
>>> so-on may be mounted to the chassis.
>>> Non rigid mountings to keep the noise down would be good.
>>>
>>> The whole system may  may be covered with .015" stainless shielding
>>> spaced one inch at least off of the tubes.  Air blowing between the
>>> shielding and the header/exhaust tubing does a good job of reducing
>>> temperatures under hood/cowl, and keeps the shielding from radiating
>>> higher
>>> temps.
>>>
>>> Been there. Done that.
>>>
>>> Lynn E. Hanover
>>>
>>> In a message dated 1/20/2017 9:11:57 A.M. Eastern Standard Time,
>>> flyrotary@lancaironline.net writes:
>>>
>>> My problem with the wrap is that it makes inspection somewhere between
>>> difficult and impossible.  I opted for wrapping the muffler in a .025
>>> stainless shroud that went all the way to the air exit,  and ducting
>>> airflow through it.  Sort of a muffler over the muffler.  It'd be heavy=
,
>>> but the shroud could have been lined on the inside with blanket materia=
l
>>> for more heat isolation.
>>>
>>>
>>>
>>>
>>> On Friday, January 20, 2017 1:48 AM, Todd Bartrim <
>>> flyrotary@lancaironline.net> wrote:
>>>
>>>
>>> So I'm interested to hear about thoughts on exhaust wraps? I know that
>>> some people like them and others don't. Also some header manufactures
>>> don't
>>> like them. But the fact is that we have one heck of a lot of radiant
>>> heat
>>> under the cowl. Heat shields help some but I really just want to try to
>>> keep most of the heat going down the exhaust pipe. I know ceramic
>>> coating
>>> on the inside of the pipe is the best solution, but once a pipe is no
>>> longer new it becomes more difficult to apply and hope for it to stay.
>>> On
>>> my first ever engine build I had my rotors ceramic coated as that was
>>> supposed to reduce oil heating, but after I had a little detonation
>>> incident I found during the rebuild that much of the ceramic had come
>>> off
>>> due to the shock of detonation. In my mind, I don't feel that ceramic
>>> coating the outside of the pipe is any better than wrapping them as the
>>> heat is still absorbed by the metal but unable to radiate out.
>>>    But the biggest argument against ceramic coating is that once it's
>>> done, you can't modify your pipe (welding etc.) without having it redon=
e
>>> again. A good example of this just happened as I'd already had my
>>> exhaust
>>> completed some months ago, not expecting that it would change again...
>>> But
>>> then somebody on this list started saying how great his PLX wideband
>>> sensor
>>> was, blah, blah, blah, and suddenly I'm out a couple of hundred bucks
>>> and
>>> having to redo my exhaust because it's recommended that the sensor be
>>> located at an 15 degree angle, no less than 36" downstream from a turbo=
,
>>> while my old narrow band sensor was only 14" downstream. So rather than
>>> leaving the old sensor in place I decided to cut it off along with
>>> another
>>> (long ago) incorrectly placed EGT port and weld a patch over it, then
>>> install a new O2 bung downstream. Pretty simple to unwrap, weld and
>>> re-wrap.
>>> So as far as wraps go... lets hear it. Good, bad or ugly.
>>>
>>>  Next is blankets. I have the original mazda metal turbo shroud in plac=
e
>>> but then I bought a large turbo blanket to fit over that. The exhaust
>>> manifold that the turbo bolts to also has a stck Mazda metal sheild but
>>> I
>>> made one to fit over that as I feel these 2 items probably account for
>>> the
>>> largest source of under-cowl heat and since the oli cooler is directly
>>> below that, I want to eliminate that source of radiant heat transfer. I
>>> made this cover using 2 different styles of welding blanket sewed
>>> together
>>> like a quilt. The ball joint in my exhaust pipe, I decided to also cove=
r
>>> with a blanket like this rather than wrapping it, so I made it into a
>>> sleeve that slides over the joint. Finally we get down to the muffler
>>> which
>>> is located inside a housing (more on that in a another post), due to
>>> it's
>>> location inside a housing I decided to put a quilted blanket sleeve ove=
r
>>> that one too.
>>>
>>> Pics of all this and more at this link.
>>>
>>> https://goo.gl/photos/NvD5YH4jwbktESi88
>>>
>>> Todd Bartrim
>>>
>>> C-FSTB
>>> RV9 13Bturbo
>>>
>>>
>>>
>>
>>
>