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Re: Bloomin' Sidepipes [Re: dodgyken] #535525
03/10/18 08:27 AM
03/10/18 08:27 AM
Joined: Jul 2018
Posts: 139
Salisbury Plain
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Gareth H Offline
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Joined: Jul 2018
Posts: 139
Salisbury Plain
I had my S3, which has side pipes noise tested at Thruxton this week, they have a 90db noise limit, was very surprised to hit 86db at 4000rpm, it sounds much louder than that!


Gareth
Aero 8
R Nine T
335d
BMW Power!
Re: Bloomin' Sidepipes [Re: Gareth H] #535702
04/10/18 01:13 PM
04/10/18 01:13 PM
Joined: Mar 2013
Posts: 854
Guildford, UK
R1NGA Offline
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R1NGA  Offline
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Guildford, UK
Originally Posted By Gareth H
I had my S3, which has side pipes noise tested at Thruxton this week, they have a 90db noise limit, was very surprised to hit 86db at 4000rpm, it sounds much louder than that!


I really wouldn't read too much into that as noise testing procedures like this are hopelessly open to variance and massively unreliable. What they do allow however is for venues to disallow obviously noisy cars on track days where they would upset the neighbours - it's a neat way to show a black & white reason why a car can't run.

I did 2 track days at Goodwood the other year in the same car (Renaultsport Spider), just 2 weeks apart. Pretty much the same weather, nothing had changed yet first test measured 96dB (4,500rpm, 0.5m, 45deg angle) and the second 106dB. Given that the logarithmic scale means that +3dB is broadly twice the volume, that's one heck of an increase. Different bloke measured using the same device on the same settings (I asked for proof that they were doing it correctly). Maybe the wind was in the other direction of there were more reflections off other cars in the vicinity, but either way it's an imprecise science at best - certainly under 'field conditions'.

Years before I'd also been refused track access for a Yamaha R1 with the stock factory dustbin-sized exhaust can, which they insisted on noise testing at 3/4 max revs that day (@9,000rpm). The noise off the cam-gear was as horrific as you'd imaging and the bloke said that the 102dB it measured was too high and I was not allowed on. EU Type Approval plate on headstock read 78dB exhaust noise at 7,500rpm as homologation, which is almost silent. I complained and was asked to try a ride by reading instead, fortunately. Did a couple of laps and I think Parkie actually missed me first time round as he never heard me coming. It was quiet, of course, and I was allowed on.

It's all a conspiracy you know....

/RANT=OFF.

Re: Bloomin' Sidepipes [Re: R1NGA] #535735
04/10/18 04:55 PM
04/10/18 04:55 PM
Joined: Jul 2018
Posts: 139
Salisbury Plain
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Gareth H Offline
L - Learner Plates On
Gareth H  Offline
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Joined: Jul 2018
Posts: 139
Salisbury Plain
Originally Posted By R1NGA
Originally Posted By Gareth H
I had my S3, which has side pipes noise tested at Thruxton this week, they have a 90db noise limit, was very surprised to hit 86db at 4000rpm, it sounds much louder than that!


I really wouldn't read too much into that as noise testing procedures like this are hopelessly open to variance and massively unreliable. What they do allow however is for venues to disallow obviously noisy cars on track days where they would upset the neighbours - it's a neat way to show a black & white reason why a car can't run.

I did 2 track days at Goodwood the other year in the same car (Renaultsport Spider), just 2 weeks apart. Pretty much the same weather, nothing had changed yet first test measured 96dB (4,500rpm, 0.5m, 45deg angle) and the second 106dB. Given that the logarithmic scale means that +3dB is broadly twice the volume, that's one heck of an increase. Different bloke measured using the same device on the same settings (I asked for proof that they were doing it correctly). Maybe the wind was in the other direction of there were more reflections off other cars in the vicinity, but either way it's an imprecise science at best - certainly under 'field conditions'.

Years before I'd also been refused track access for a Yamaha R1 with the stock factory dustbin-sized exhaust can, which they insisted on noise testing at 3/4 max revs that day (@9,000rpm). The noise off the cam-gear was as horrific as you'd imaging and the bloke said that the 102dB it measured was too high and I was not allowed on. EU Type Approval plate on headstock read 78dB exhaust noise at 7,500rpm as homologation, which is almost silent. I complained and was asked to try a ride by reading instead, fortunately. Did a couple of laps and I think Parkie actually missed me first time round as he never heard me coming. It was quiet, of course, and I was allowed on.

It's all a conspiracy you know....

/RANT=OFF.

I've had a bit to do with noise testing commercial aircon, and you're right it always seems to be more of an art than a science, but 10db difference is huge, I wonder how often the circuits calibrate their measuring equipment?


Gareth
Aero 8
R Nine T
335d
BMW Power!
Re: Bloomin' Sidepipes [Re: Gareth H] #535758
04/10/18 06:37 PM
04/10/18 06:37 PM
Joined: Jul 2007
Posts: 22,832
Cheltenham, Glos. UK
Graham, G4FUJ Online content
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Graham, G4FUJ  Online Content
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Joined: Jul 2007
Posts: 22,832
Cheltenham, Glos. UK
Annually at minimum to comply with MSA from what I remember, as a former trainee Environmental Scrutineer.

From the same role I'm also aware of how difficult it can be to get an accurate reading. However, from MSA perspective it is overall noise, not just exhaust. The instructions are to not carry out noise tests in a confined area.

(It's a few years since I did any of this so rules may have altered and my memory is not quite what it was oldgit grin2 )


Graham (G4FUJ)

D8921 L44FOR '93 4/4 Giallo Fly 2 seat smile
'90 LR 90 SW
'07 MINI Cooper
Re: Bloomin' Sidepipes [Re: dodgyken] #535829
05/10/18 08:05 AM
05/10/18 08:05 AM
Joined: Aug 2013
Posts: 861
Switzerland
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dodgyken Offline OP
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Joined: Aug 2013
Posts: 861
Switzerland
Another update from the importer:
Morgan refused to change the CoC
They are now working with an exhaust specialist to build a custom exhaust that will record 86dB in accordance with the Swiss measuring regulations.

Car due back 19th October


2010 Aero Supersport | 2017 VW Multivan | 1996 BMW M3 Evo
Re: Bloomin' Sidepipes [Re: Gareth H] #535841
05/10/18 09:25 AM
05/10/18 09:25 AM
Joined: Feb 2016
Posts: 2,038
East Harling, Norfolk UK
Richard Wood Offline
Talk Morgan Expert
Richard Wood  Offline
Talk Morgan Expert

Joined: Feb 2016
Posts: 2,038
East Harling, Norfolk UK
Originally Posted By Gareth H

I've had a bit to do with noise testing commercial aircon, and you're right it always seems to be more of an art than a science, but 10db difference is huge, I wonder how often the circuits calibrate their measuring equipment?




Richard

2018 Roadster - Red/Magnolia - "Morton"
1967 Land Rover series 2a SWB
1960 Velocette Venom
Re: Bloomin' Sidepipes [Re: dodgyken] #535978
06/10/18 07:21 AM
06/10/18 07:21 AM
Joined: Mar 2013
Posts: 1,109
Zurich, Milan
Ale_72 Offline
Has a lot to Say!
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Has a lot to Say!

Joined: Mar 2013
Posts: 1,109
Zurich, Milan
I love the "power gain factor" love


2010 Violet Aero Supersports | 2010 White Boxster Spyder
Re: Bloomin' Sidepipes [Re: dodgyken] #536156
07/10/18 12:13 PM
07/10/18 12:13 PM
Joined: Sep 2009
Posts: 4,230
Köln, Germany
Heinz Offline
Part of the Furniture
Heinz  Offline
Part of the Furniture

Joined: Sep 2009
Posts: 4,230
Köln, Germany
Double of loudness perception is almost a factor of 6dB.
http://www.sengpielaudio.com/calculator-levelchange.htm

Ah I see, Sengpiel uses the same sheet you have posted, Richard, further down on his page.

Last edited by Heinz; 07/10/18 12:15 PM.

'14 4/4 graphite grey
Re: Bloomin' Sidepipes [Re: dodgyken] #536258
08/10/18 05:21 AM
08/10/18 05:21 AM
Joined: Aug 2013
Posts: 861
Switzerland
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dodgyken Offline OP
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Joined: Aug 2013
Posts: 861
Switzerland
Meanwhile I got an email from "my" exhaust man who is scratching his head on how it would be possible to get the sidepipes down to 86dB.

It is now just a waiting game


2010 Aero Supersport | 2017 VW Multivan | 1996 BMW M3 Evo
Re: Bloomin' Sidepipes [Re: dodgyken] #538136
18/10/18 05:26 PM
18/10/18 05:26 PM
Joined: Aug 2013
Posts: 861
Switzerland
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dodgyken Offline OP
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Joined: Aug 2013
Posts: 861
Switzerland
My exhaust man was right - not a chance in hell of hitting 86dB - but it is now down to 91dB - which is withing 3% or 5dB of the CoC limit.

Which means the car failed.

Failed? Yes - failed.
But it passed the noise test? Yes - but it failed to have any paperwork for the exhaust

So what this means is the car will tomorrow get booked in at FAKT to have the exhaust homologated - which is good news for me, but less good news for any other sidepipe equipped Supersport in Switzerland.

My understanding is that once the homologation has been completed and the paperwork submitted to the STVA only those cars equipped with this particular side exhaust will pass the MFK.

I will get all this clarified - and also provide details of the exhaust supplier - in due course, and once the car is sat back on my drive!


2010 Aero Supersport | 2017 VW Multivan | 1996 BMW M3 Evo
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