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small silencer
smart51 - 28/3/07 at 08:25 PM

What do you think to my new silencer? It has 2" OD ends so will replace the link pipe between my collector and existing silencer. Thanks to Nick Skidmore for the welding. Rescued attachment small silencer.JPG
Rescued attachment small silencer.JPG

mookaloid - 28/3/07 at 08:36 PM

Will it do much?

smart51 - 28/3/07 at 08:38 PM

quote:
Originally posted by mookaloid
Will it do much?

I don't know. At 130mm long, it's 1/5 the length of my main silencer. I made an excel model of silencing which suggests that silencers give a dB/mm noise reduction regardless of length so I expect 20% more silenceing that just the old can on its own. How much that is I don't know. Some.

mookaloid - 28/3/07 at 08:50 PM

In these days of ever decreasing noise limits it has got to help.

I would be interested to know what effect it has - a before and after noise test would be good. have you had it tested before?

cheers

Mark

smart51 - 29/3/07 at 07:03 PM

Well mixed results, as always it seems. Quietly I was especting 4 - 6dB(A) and I got 5. Sadly, it was about 2dB louder than I was expecting "before" so the "after" figures are only OK.

Bizarely, the 7500 RPM (3/4 of max power) figure is louder than 8800 RPM (3/4 of max revs). The bonnet has developed a rattle against the scuttle since the weekend which I'm sure is affecting the results. I've got a bit of foam tape which will sort that out.


Oh, and one of the exhaust clamps had rusted solid, so much that I snapped the bolt trying to undo it.

RPM____before____after___saving
idle_____87.1_____82.3____4.8
7500 ___102.6____101.5___1.1
8800 ___105.1____99.9____5.2

I was hoping for a nice, comfortable 98 - 99dB to get me in at 100 dB track days. Maybe I can squeek a bit more out somewhere.

[Edited on 29-3-2007 by smart51]

[Edited on 29-3-2007 by smart51]

smart51 - 2/8/07 at 11:49 AM

Just an update for the archive. I had my car noise tested at Cadwell Park yesterday. 96.7 dB(A) at 8800 RPM. Their noise meter reads about 3dB quiter than mine. Come to think of it, so did the noise meter at Elvington.

[Edited on 10-6-2008 by smart51]