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106db down to 99db
ashg - 22/2/10 at 12:11 PM

ok guys after getting 106db exhaust noise reading at my IVA i need to get the noise down. realistically how hard is it going to be to get a 7-8db drop from my silencer by modifying it internally?

should i try or just get a new one?

it is a straight through type, so was wondering if i took it apart and zigzagged the perforated tube through it added a couple of baffles then repacked it would it reduce the noise enough?

i know it will increase the back pressure but i will just have to live with that.


ragindave - 22/2/10 at 12:15 PM

You want one of these.

http://cgi.ebay.co.uk/MOTORCYCLE-EXHAUST-BAFFLE-SILENCER-48mm-CAN-BAFFLE-NEW_W0QQitemZ350276156751QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item518e 15fd4f

Should do the trick


MK9R - 22/2/10 at 12:48 PM

quote:
Originally posted by ragindave
You want one of these.

http://cgi.ebay.co.uk/MOTORCYCLE-EXHAUST-BAFFLE-SILENCER-48mm-CAN-BAFFLE-NEW_W0QQitemZ350276156751QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item518e 15fd4f

Should do the trick


was going to suggest that, or alternatively take can apart and squash the perforated tube. Are you sure the can is packed correctly, i.e. not to tight or too lose?


smart51 - 22/2/10 at 12:52 PM

I took out the link pipe between my manifold and silencer and added an extra silencer inbetween. I had it made with 2" OD end pipes (rather than 2" ID) so that it just slotted in. The can was 6" in diameter, the same as my main silencer but was only 5" long plus the end pipes. My noise went down by 5db from 102 to 97 dB(a). You will need a longer one to get 7 or 8dB but that shouldn't be a problem.

The best thing is that this approach does not restrict air flow or power, unlike baffles or dB killers. And is saves your ears. 97dB is plenty loud enough at full throttle.


rgrs - 22/2/10 at 01:03 PM

Which silencer do you have ? any pic's

Its a lot to drop, worth opening up your existing and seeing how it's currently packed.

When i opened mine up (mk eng) not a lot inside repacking it dropped me nearly 5dB.

The chances are the dB killer above won't fit if you have a swept bend on the exit of the silencer and it's only a quick fix not a long term solution.

Also re: induction noise worth putting some sound material under bonnet and make sure when its re-tested the bonnets on, also on re-test get as far away from the building as you can. If its tested in the exit from the speedo test i think its too close and could be affected by the building.

Roger


big-vee-twin - 22/2/10 at 01:36 PM

If you use the baffle from ebay it will need wrapping with fiberglass, to be honest I've used one on my bike, it didnt make too much difference


spdpug98 - 22/2/10 at 02:01 PM

I had to the same with mine, well to 101dB but did get it down to 99ish

I used a back box from a Volvo about 9-10" dia, and fully lined my bonnet and body side panels with accoustic foam


boggle - 22/2/10 at 02:24 PM

you can fit a bung in the end...

i had one on my subaru for its mots....


Werner Van Loock - 22/2/10 at 07:16 PM

going down 8dB is an awfull lot, every +3dB is double noise, so going down is the opposite, so have fun

it's not a linear scale you know


Dangle_kt - 22/2/10 at 07:20 PM

errr...do you have a tacho that can be...errrr... calibrated?


RichardK - 22/2/10 at 07:40 PM

quote:
Originally posted by Dangle_kt
errr...do you have a tacho that can be...errrr... calibrated?


They can use their tacho though! Think its going to be a case of trailer it there or get there dead early and pack as much loosley packed steel wool up there and hope it doesn't blow out! Together with sound deadening material under the bonnet and sides.

Good look mate its a lot to drop but doable.

Cheers

Rich

Or put a turbo on it that should deaden the sound a bit

[Edited on 22/2/10 by RichardK]