I'm rebuilding the factory mufflers on my z06. It has a factory cutout (npp) that has a muffler [semi-] bypass but it necks from 3" to nearly 2 1/4 through the middle.
so I am cutting them open and replacing the middle with a true 3" system.
but the mufflers I am modifying had been opened up before and had no packing. It looks like they came with some sort of fiberglass material.
I can't find anything made for automotive use, only silencer packing for dirt bikes.
Would that suffice? Any sources for other quality packing?
do I even need it? I want it pretty quiet when the pipes are closed and don't want to put it together sans material just to find that it's too loud or droney or resonant.
demnted
New Reader
10/3/21 7:05 p.m.
steel wool/ fiberglass matting? I would imagine stainless steel wool would be the material in question.
I used some ceramic packing material I got from Thermal Solutions on eBay. I used 1x12x24 sheets. I calculated an internal volume of 500ci, the amount of packing material I used was a little over double that. Tighter packing means more noise reduction, according to stuff I read online anyway. Plus, the nature of the internal geometry meant I was more like stuffing a pillow than wrapping a perforated tube.
The noise reduction was.... substantial. On a rotary.
The ads probably list dirtbikes as the application, because dirtbike mufflers seem to be repackable while automotive mufflers aren't, unless you enjoy cutoff wheels and welding.
Burns Stainless sells the stainless packing, as well as fiberglass packing.
I have used high temperature ceramic kiln insulation for some side pipes. Seems to work, but could use more/tighter packing as Pete noted.
Back in the November 14 issue, we went over how to repack a muffler.
You can read the full story with GRM+, but for the project we got fiberglass from Bristol Core that's meant to be used to repack a muffler.
I used lava rock in my muffler for the RX7. Worked great and has held up for several years.
Steel wool from NAPA works great.
