Board logo

The 6 P's
westf27 - 19/4/06 at 09:44 PM

Perfect preparation prevents wee poor performance.Failed SVA today on stupid little points thrashed to death on here and should have been sorted on final checks,half a days work max.

Still,need your help,Tiger silencer (new) on 2L Pinto 103db! needs to be max> 101db.Is this common,could engine tune cause this if so what to check?Dare i ask if these silencers are good.All offers appreciated.

Chippy - 19/4/06 at 10:37 PM

Can't you put an exhaust restrictor in the line, that should do the trick. Then take it out after SVA. atb Chippy.

westf27 - 19/4/06 at 10:51 PM

sounds good where to obtain

Danozeman - 20/4/06 at 06:19 AM

Is it repackable? If so could u not ram some more wadding in?

Guinness - 20/4/06 at 06:51 AM

Once again, I have a bit of kit that has fallen off my car since the SVA. DB Killer like this one, only not so clean, a bit discoloured by heat!




New on ebay for £12 delivered, or you can borrow mine for the cost of the postage out and back. I'll need it back for my next track day though! That's looking likely to be June. You'll be passed by then though!

Let me know if that's any good to you!

Mike

jos - 20/4/06 at 07:08 AM

Whip the silencer off, get a pair of socks, stuff em into the inlet, pop the silencer back on and see how you get on.

Socks are sacraficial in this instance and you'll probably get at least one new pair at christmas

bimbleuk - 20/4/06 at 09:37 AM

You could check the exhuast wadding as too tightly packed will inrease the dB.

I've had good results from using half an inch of wire wool surrounded by a loose wrap of ceramic felt matting.

Car Builder Solutions do a very reasonable packing bundle for 5" or 6" inch cans.

DavidM - 20/4/06 at 11:58 AM

Can you tell us what you failed on, just so I can check I've got those bases covered.

David

iank - 20/4/06 at 01:04 PM

quote:
Originally posted by westf27
...

Still,need your help,Tiger silencer (new) on 2L Pinto 103db! needs to be max> 101db.Is this common,could engine tune cause this if so what to check?Dare i ask if these silencers are good.All offers appreciated.


Well if they are sold as bolt on SVA compatible silencers for the 2L pinto then no they aren't good by definition really. 103dB is a long way from 101dB (log scale means 104dB is twice the sound intensity as 101dB!)

The revs you tested at will affect the reading, what was yours tested at?

Exhaust restrictor is a cheap hack that should get you through, but at some point the SVA testers will get wise to them.

MikeRJ - 20/4/06 at 02:06 PM

quote:
Originally posted by iank

Well if they are sold as bolt on SVA compatible silencers for the 2L pinto then no they aren't good by definition really. 103dB is a long way from 101dB (log scale means 104dB is twice the sound intensity as 101dB!)


dBA's are a slightly odd scale, you actualy need a 10dB increase for a perceived doubling of loudness. The same scale also attempts to take into account the non-linearity of the human ear, so at high and low frequencies you need more sound pressure to achieve the same dBA rating than at the mid-frequencies.

jos - 20/4/06 at 02:25 PM

sacraficial socks sacraficial socks

MikeRJ - 20/4/06 at 02:26 PM

quote:
Originally posted by jos
sacraficial socks sacraficial socks


Would look bad failing again for having flaming socks being projected out of the exhaust though

iank - 20/4/06 at 02:51 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by iank

Well if they are sold as bolt on SVA compatible silencers for the 2L pinto then no they aren't good by definition really. 103dB is a long way from 101dB (log scale means 104dB is twice the sound intensity as 101dB!)


dBA's are a slightly odd scale, you actualy need a 10dB increase for a perceived doubling of loudness. The same scale also attempts to take into account the non-linearity of the human ear, so at high and low frequencies you need more sound pressure to achieve the same dBA rating than at the mid-frequencies.


Agree, which is why I carefully said sound intensity, rather than loudness.

But I don't think it makes a lot of difference for car exhast systems since dbA rolls off very sharply below 1kHz and to a lesser extent above 10k - so anything but a screaming BEC is going to be soundly in the middle of the 0dB (or worse) part of the dBA filter. So dB is more or less the same dBA in the range we are interested in.

http://www.phys.unsw.edu.au/~jw/dB.html#absolute