Hi Dennis,

It looks like the hot cross tube is awful close to the radiator.
Besides blocking flow, it will radiate a lot of heat back into the
cooling system.  Have you done enough high power engine running to know
if it's going to cool OK?

I have a similar situation although not quite as bad as what I see in
your picture.  I'm sort of leaning toward running pipes into a 2 to 1
collector and straight out past the cabin.  If the noise is just way
too loud, I might add some sort of muffler after that.

Bob W.



On Thu, 08 Feb 2007 21:22:46 -0600
Dennis Haverlah <clouduster@austin.rr.com> wrote:

> The weather was so good I managed to paint my fuselage and finally
> removed the exhaust heat shield to take pictures.
>
> The exhaust manifold is stock RX-8 cut off about 2 inches past the last
> rotor.  The exhaust comes out toward the front of the aircraft.  To turn
> the exhaust 180 degrees I first went into a 4 inch dia. cross tube .  
> The exhaust enters tangentially to the 4 in. cross tube and circles or
> swirlls as it goes out into the muffler.  The cross tube is sealed using
> flat stainless steel.  I had this built before the discussion by Lynn
> about using convex end caps!  To help keep it together I had my welder
> install a 3/8 in. SS rod through the center of the two end caps.  This
> ties them together.  Only time will tell if this will work.  I can say
> that the Renesis exhaust is not nearly as sharp as an RX-7.  The
> fabricated parts of the exhaust are 302 SS .063 in. thick I believe.  
> The outlet of the 4 inch cross  tube is a flexable ball/socket fitting
> from the local muffler shop.  The muffler is a Flowmaster -Hushpower II
> "The Resonator"  part # 12512400 with 2.5 inch inlet and outlet.  The
> muffler outlet gos into a 2.5 inch. SS pipe that was purchased and
> fabricated at the local exhaust shop.  It also is 302 SS .063 in. thick.
>
> Everyone that has heard the engine run comments that the exhaust is much
> quiter than the prop and the exhaust notes are quite low pitched.
>
> Dennis H.
>
>


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