I'm marginal on a noise test at the moment, 99dB (A) on a 100dB (A) day.

So, wadding, is it the quantity, the quality or how tight it's packed?

Whaddya think people?

I imagine it's more of an equation - the better the quality, the less you need, the poorer the quality, the more/denser you need.

I used to pack my bike silencers with wire wool, packed fairly tight it made a big difference to the noise (and its cheap)

Cheers

Alex
PS
downside is, it doesn't last very long

I seem to remember reading somewhere that if it is packed too tightly the silencer can't do its job and actually gets noisier.

True. And if it's packed really loose (or not secured from movement in the can), the exhaust pulses will drive it to one end and pound it into a solid mass that won't absorb any sound at all. Regular wire wool will rust away very quickly if you run the engine in anything but dry, hot weather. Try stainless-steel wire wool, or if you can get them from a machine shop, stainless-steel lathe turnings. They last forever!

I wrap the centre tube with stainless steel wire and secure it with a length of stainless steel wire. Then I fill the rest of the can with rockwool cavity wall insulation - cheap, I'm still only 1/2 way though a £20 bale from Wickes in just over 12 months.



ps.. and I tend to repack the silencer before each trackday I do, which is about 5-6 per year.

[Edited on 8/11/06 by givemethebighammer]

Thanks guys, Rockwool insulation added this morning took 9 dB off at 4500 rpm and cheap as well. Now down to 90 dB so will breeze the static test.