Exhaust Insulating Wrap

[vdecoster]

Has anyone tried insulating/wrapping the headers and exhaust to reduce heat on the cowling of Long-EZs using a product like this from Thermo-Tech: http://www.thermotec.com/exhaust-insulating-wrap.html?

[A. Bruce Hughes]

I did that some years ago and I was VERY, VERY, VERY sorry that I did.

At the time, I was just taxi testing the Longeze a couple of days per week;
it never flew.

I found some of the 8 bolts that hold the exhaust manifolds were rusting
badly.   Those were the "special exhaust bolts" sold by ASSC for Lycoming
engines.   There were not cheap crap!

What was happening, I assume, was the insulating wrap was holding the heat
in the exhaust, especially around the exhaust valves.   The higher heat level
made the rusting occur more rapidly.   The total taxi time was less than one
hour!

2 nuts were so bad that I could not get them off initially.   I finally had to
file the 2 nuts on 2 sides to fit a 5/16 open jaw wrench, turn the nut 60 degrees,
file again, turn again, file the 3rd time and turn again.   At that point I could
gradually turn the nut all the way off.

Doing that filing in an area that is hard to reach was extremely time consuming.
That is one of the reasons I have been working on the airplane so many years.

That insulation is sold to make a profit for the manufacturer, not to improve
your engine.

Find another way to shield the fiberglass.

Bruce Hughes   

[AaronT]

I'm sure I read something in the CP's about insulation being a bad idea.   I just can't find it at the moment.

[vdecoster]

Bruce and Aaron, thanks for the advice! I'll likely add additional insulation to the inside of the cowling. Again, thanks.

[eric r]

Here's my two cents. Header wrap is not good! A coating (I use jet-hot) applied inside and outside .. pay extra and get it done right .. WILL speed the flow of the exhaust gas out of the pipe, while insulating the pipe. The down side may be the heat of the exhaust gas at the tips; watch out for that, although it shouldn't be an issue of your prop is clocked correctly. I have used the stuff for years on race cars and aircraft. It does decrease backpressure, which in most cases incrreases power. It also decreases heat buildup at the flanges...all good. O.K, that was a dimes worth, but I have experienced power increase in race engines, AND an IO-470 in a Bonanza.
i.e., a measurable increase in rpm on takeoff and climb with no prop governor setting change = more power being produced.
Yes naysayers, you can still detect cracks if they occur. In fact, the process will show any defects in your exhaust (pinholes and substandard wall thickness) prior to the coating.

[AaronT]

Found it...  CP 46 page 7 (knew I'd seen it somewhere!)...

Ralph Gaither, Safety Officer for the Navy and a high time VariEze
pilot, reports what he considers to be a possible flight safety problem
for pilots using a product call Thermeeze Tape (high strength ceramic
tape).  He purchased this product from Sport Flight in Florida.  Ralph
installed this tape per the instructions, to his exhaust pipes (this EZ
already had over 800 hours of flight time).  Within 100 hours the
cowling was burned completely through in close proximity to the ceramic
tape.  In addition the tape crystallized broke down to a powder and
generally fell apart into the cowl.

Ralph is very concerned that with this condition and the use of
carburetor heat, some of the powdered ceramic tape could be ingested
into the engine, possibly causing engine stoppage.  In addition to
this, Ralph noticed no benefit whatsoever to the operation of his
engine.

RAF has never recommended this tape or any other similar material.  If
you are using it, we suggest an immediate, careful examination of the
tape before next flight.  Sport Flight has been informed of this
problem.

[saybeengineering]

Yes the cowling gets really hot in general. What I did is to installed (glued) a thermal blanket in the inside of the top cowling to provide an extra layer of protection to the cowling. I also have the thermal wrap on the exhaust and it generally speaking, after landing, the cowling is hot to the touch.....I 've used it for more than 75 hours and have not seen any kind of degradation. My philosphy is an extra layer to protect the cowling....

Afif

[A. Bruce Hughes]

Did you read what I posted earlier?    A thermal wrap on the exhaust is a VERY BIG
mistake.    You will be very sorry if you leave it on.....

Bruce Hughes