M uitlaat tjoenen

[Ivo]

http://www.z3mcoupe.com/forum2/viewtopic.p...&highlight=

[napoje]

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[ChrisXL]

have now opened up two OEM silencers and performed some internal "surgery" on the innerds. Before I weld the silencers back together I would like the opinions of those that know (no guessing please). If the flow through the silencers is permanently improved will this have an adverse efect on engine performance at low revs when there is minimal back-pressure? Are there any other drawbacks to an improved flow through the silencers?

For those of you who are interested, the photo below shows the surgery I've performed. The photo shows the view of the underside of the silencer

The photo shows the third and final chamber inside an OEM silencer. You can see the mouth of the inlet pipe on the left; normally, the exhaust gases leaving the inlet pipe have to pass backwards into the previous chambers through two smallish perforated pipes (you can just make out one of them in the photo) interconnecting the chambers before the exhaust gases can exit the silencers. You can see that my surgery has been to cut two rectangular windows through the outer tube lining of the outlet pipes to reveal the inner perforated tube of the outlet pipe, so that the exhaust gases can pass from the inlet pipe to the 2 outlet pipes within the third chamber, thus making the flow of exhaust less tortuous, and thus more "free-flowing".

Obviously, I'd like to have to put these silencers on and off my car as few times as possible before I decide that the job is complete. So, I've been giving much consideration to all the different possiblities to improve both performance and sound. It would be a relatively simple task to remove a whole section of the two outlet pipes so that the flow of exhaust gases would be very free, but I'm concerned that the noise may then be too loud.

I've made a pair of collars, which fit around the outside of the outlet pipes so that the the apertures of the windows in the outlet pipes can be "tuned". The photo below shows them in place and temporarily held by jubilee clips.

The collars will be adjustable by inserting a tool up the outlet pipes so that the aperture can be adjusted to change the sound (if that's possible).

If it is suggested that what I have done will cause reduction in power at low revs due to lack of back pressure, then I shall make a weighted flap on a hinge which will be attached to the mouth of the inlet pipe in the final chamber (similar to those seen on tractors) so that when the flow of exhaust gases increases the pressure in the inlet pipe will lift the flap so that the inlet pipe is completely open.

Any useful suggestions that any of you may have, please shout up!

[M-roadster]

En dit zijn jullie nu ook van plan??

[ChrisXL]

nah............. dan had ik wel een .... genomen

[Edwin]

oh God ....... niet weer ................

:D