Paul,
It appears to me that you could rotate the muffler can about the axis of

the

forward exhaust port centerline about 20 to 30 degrees clockwise.  This

would make

the exhaust bends shallower at the expense of making the cooling air take

a small

(20 to 30 degree) turn to enter the interior cooling pipe.  It would also

setup

the exhaust pulses so that the forward rotor's pulses swirl left-hand, and

the

rear rotor's pulses swirl right-hand; dunno if that's good or bad.

Russell Kent

I think it would be bad. I think it would tend to cancel the swirl.
the swirl is good as it causes the high speed exhaust gases to rub
on both the outer can and the inner can. According to the book the
Scientific Design of Exhaust and Intake Systems This rubbing action is the
main phenomena that causes a reduction in the noise level. The energy
in the noise is converted to additional heat in the skin of the muffler.
In this case both the inner tube and outer tube skins. If this vortex can be
maintained in the tail pipe in theory a further reduction of noise
will take place.

Paul Lamar

-David Stricker wrote:

Paul,

In the 70's (and perhaps later years) Mazda used a thermal reactor on the
rotaries to meet emissions without the use of a catalyst.  The thermal
reactor was a heavy cast iron chamber mated to the exhaust ports.  The
theory was to take the exhaust gases as they enter the thermal reactor and
mix with outside air, which was pumped in from a belt driven air pump.  This
was highly effective at cleaning up the exhaust gas however; one of the side
effects was a lot of heat due to the amount of unburned fuel in the exhaust
being burned in the thermal reactor.  That's why the thermal reactor was
made of cast iron, to handle the heat.  My concern here is that this
arrangement may be creating the same environment.  At the point where
exhaust gas mixes with outside air, there will be enough residual heat in
the exhaust gas (particularly at cruise and take off power) to ignite any
unburned hydrocarbons as it mixes with fresh air.  If my theory is correct,
this setup may create more heat than the tail pipe can handle.  It may
create more heat in the exhaust system than compared to a straight pipe.
But again, I'm no expert.

Dave Stricker.....just listening and learning

That is a very good point. We may have to increase the metal thickness
in that area. There are non contacting infrared thermometers that I can
use to measure the metal temperature while the engine is running on the 
dyno. With the RX8 engine this problem will be drastically reduced
as unburned hydrocarbons are mostly recycled.

Paul Lamar
 
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