Paul,
              Finally got the exhaust back together and gave the engine a
work out and am very pleased with the results.  Static run at a fairly cool
20 degrees C which is somewhere near the 60 degrees far. ( a
guess)   With flaps closed the engine and oil just got over 180 degrees
at full noise.  At that rate I will handle summer temps well, up to 45
degrees C.  Max rpm at static was somewhere around 6300 and if I richen the
mix I get over 6400 plus, nearly 6500.  Egt gets up to 1800 and barely over,
so the modified manifold has dropped that around 200 degrees as Mark said.
Oil pressure good, from 90 psi at cold down to 75 psi at 180 degrees. Engine
runs very nicely, very pleased with it, held full noise for 10 minutes.
Engine mapping complete but not perfect probably never will.
        Now the bad bit.  At full noise I was getting hot vapour into the
cab and checked the fuse immediately after shut down, and could not hold my
hand on the fuse (fibreglass).  Will have to install a heat barrier.  What
options do I have??  Need a strip about 4 feet long to get past the mufflers
and possibly 15 inches wide.  Prefer to mount onto the pipes and not the
fuse, but at the end of the day, Whatever works best. Suggestions??  Neil.

    There is stuff called fiberfrax. Used with a thin layer SS. But it has
to
    go on the fuse. The SS reflects a lot of heat because radiation from
    the pipe is the main cause of heating adjacent surfaces. The other
thing
    about SS is it does not conduct heat well. That is a good thing.

    http://www.fiberfrax.com/


    In the air it won't be so bad due to cooling flow. 10 minutes
stationary full chat is worst case.


    Paul Lamar

    Neil, i have Fibrefrax and Stainless sheet on the front of the
tango, the stuff is supposed to be good to over 2000 F. That's fine and
well but the cowl will melt long before then so I've got a can of heat
resistant paint to paint on the inside of the cowl, cant remember the
brand and I'm not going to be close to the hanger for another 2 months
unfortunately to check, but Google can maybe find something for you. My
last ditch effort was going to be gills on the cowl with a low pressure
setup to have prop airflow drawing out the heat.

    Alex Molteno

It is not that bad :) The exhaust is right next to the cowl on the RV4
and the
SS sheet is working fine. The gills are essential to get rid of the hot cowl
air from the rad or the engine will not cool.


Neal, do you like the sound of your new coax muffler?

Paul Lamar



Hi Paul,

Concerning the heat under the cowl,
I had a similar issue and I install two inverted NACA
At the top of the fuselage and it solved my problem.
The heat was trapped under the cowl.
I could not touch it after a couple of ground run but since
I installed these inverted NACA I can touch the cowl anytime.


A question for you: What is the diameter and pitch of your propeller?

Thanks

JP

Round holes would work as well :)

Paul Lamar

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