Reprinted from
Up-fixin der Porsche
Vol IV page 25.
Originally published in
Porsche Panorama
(Official publication of the
Porsche Club of America)
in October 1974. |
Modified 911 Muffler (Pre-1974)
By Jeffrey Gamble/Southern Arizona Region
Are you thinking of a little more Porsche sound and
performance? You can modify your factory muffler to sound much
like the factory twin pipe sport muffler that is optional in
Europe. This modification has been tried on the street by over
a dozen Porsche 911 owners with good results and with no more
noise than the expensive one. Be careful to check in your
state, however, with proper authorities before performing
such modification. It may now be or soon may be illegal in
some states.
A stock factory muffler was completely opened to determine
the most equal length from each side to the exhaust pipes with
minimal cutting and the following modification procedure was
determined.
- Remove muffler.
- Cut the factory exhaust tail pipe off at
muffler and weld an appropriate sized patch.
- Cut two round holes (2” dia.) at the bottom of the muffler for new tail pipes. In the
left hole cut a large opening through the solid divider and
half bulkhead (as diagramed).
- Cut two new tail pipe sections six inches
long from standard exhaust pipe (2” dia.).
- Shape the ends of the two new tail pipes
to the contour of the muffler. Weld in place with main axis
parallel to the seam plane of muffler (horizontal to ground
level).
- Paint muffler with high heat paint or dip
to protect against corrosion.
- Put straps over muffler and re-install.
This muffler modification may lean the fuel mixture on
injection and carburetion. Have this checked by a qualified
technician at the time
of installation.
10/74
*Note: This set up has not been tried on a
dyno as yet, I am told. It very well may be that the pipes
will work better at some length other than six inches. Correct
tuning can only be done on a dyno.
—RWC
|
|