4-stroke carbon pipe design Q's

[Bob Richards]

I had an AAP exhaust system about 13 years ago that
was tuneable to some extent. Playing with the length
of the system I was able to hit a sweet spot and gain
about 200 rpms, but was still a slight loss in rpm
over open exhaust. Of course, this was until the inner
lining of the header failed and exhaust started coming
through the outside braid.

The tuning dynamics are completely different from
two-strokes. On two-strokes, you are dealing with a
(forgive me if I mess up the terminology) reflected
wave that stuffs some of the excess unburned fuel/air
back into the exhaust port before it closes, but after
the bypass port closes, effectively supercharging the
engine. On a four stroke, you are using the inertia of
the previous exhaust pulse to help extract the next
exhaust pulse. Baffles and backpressure tend to defeat
this.

That is the limit of my knowledge on the subject,
perhaps someone else can elaborate (or correct me!).  

Bob R.
 

--- patterndude at comcast.net wrote:
> I've gotten a lot of recomendations to add a carbon
> lightweight 4-stroke pipe to our lineup so I'm
> starting to look at a 4 stroke pipe design.  I have
> some questions:
> 1. What are the proper pipe inlet diameters that you
> desire on pipes
> 2. Worst reasonable case: how close is the pipe to
> the exhaust port
> 3. What max temperature at the inlet do you suspect
> (I'll be doing detailed research on this but want
> your opinion).
> 4. Is it possible to tune a 4 stroke at all, or is
> the muffling the only goal?  If tuning is possible,
> how does this work?
> --Lance
> 
> --
> District 6 AVP 
> www.aeroslave.com
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