One silencer and 2.5" exhaust....

[sierra3dr]

.....  gets my daily 2003 Focus an MOT failure....Exhaust noise is clearly in excess of that emitted by a similar vehicle fitted with a standard silencer in average condition (8.1.1 (a)).....amongst other issues,fractured front  subframe

[Noberator]

Nov 5, 2022 13:04:09 GMT 1 sierra3dr said:

.....  gets my daily 2003 Focus an MOT failure....Exhaust noise is clearly in excess of that emitted by a similar vehicle fitted with a standard silencer in average condition (8.1.1 (a)).....amongst other issues,fractured front  subframe

It's not a standard exhaust though is it.


What is the permitted noise level?

[chippie]

Post 2016, noise level is 72dB...innit?


Pre- 2016 82dB...? from memory...


I heard its due to change to even lower levels..

[Noberator]

Nov 6, 2022 12:36:29 GMT 1 chippie said:

Post 2016, noise level is 72dB...innit?


Pre- 2016 82dB...? from memory...

I heard its due to change to even lower levels..

PARDON.

[studabear]

We don't have a decibel meter though.

I think I've only ever failed 1 as it gave me headache being underneath the car and pissed me off.

Lad at work recently failed a Mini that had had the back box chopped off and a straight pipe, thing was an auto and sounded ridiculous. Customer used to have a few bits done with us, it got a pass somewhere else a few days after so we prob lost a customer.

[valhalla]

Nov 7, 2022 22:20:20 GMT 1 studabear said:

We don't have a decibel meter though.

I think I've only ever failed 1 as it gave me headache being underneath the car and pissed me off.

Lad at work recently failed a Mini that had had the back box chopped off and a straight pipe, thing was an auto and sounded ridiculous. Customer used to have a few bits done with us, it got a pass somewhere else a few days after so we prob lost a customer.

I suspect you are not the only ones, either.

It's very difficult to measure noise objectively, and the figures quoted for noise should really be stated as dBm (decibel-metres) with a proper sound-level reference to a calibrated source. I very much doubt that any MoT station is ever going to have the facilities to do this properly, so you are left with a subjective assessment by the Tester.

Basically, if it's loud enough to cause you annoyance, then it ought to be a fail!

In fairness, it's a rare thing these days to hear a really loud exhaust on a car - it used to be a lot more common in the 1970's and 1980's. Because of the nature of my local terrain, we hear everything, very clearly, but not much nuisance these days, just the odd Impreza to spoil the peace....

[chippie]

I don’t know if it has changed, but the rules relating to motorcycles was that the original exhaust ( or it’s equivalent) had to be fitted when presenting, these had a stamp on them stating the max noise level at what ever the prescribed measurements dictated.

So aftermarket noisier silencers were not permitted..

As an aside, noise limits applied to model aircraft too, 87dB measure at right angles to the model about 3m away I believe…,

[oli]

I’ve often wondered what the situation would be with aftermarket type exhaust valves. Just tested as it is running at the time or would it count as removal of emissions equipment?

(I mean the electrically operated butterfly valves fitted upstream of the silencers/cats etc that effectively convert a vehicle to a straight through system)
Oli

[Karl]

Never failed an loud exhaust ever


But I guess you could

To be honest it’s more for the police to deal with really

Don’t know why it’s in the MOT

[sierra3dr]

Nov 7, 2022 22:20:20 GMT 1 studabear said:

 it gave me headache being underneath the car and pissed me off.

[sierra3dr]

Oh,and the "fracture subframe" is due to me being eager with the angle grinder when I changed the front wishbones several years ago,a bolt was not budging because of the corroded thread. I'm still waiting (8 days) for DPD to deliver more exhaust parts   Two more silencers have been added.

[valhalla]

Dec 14, 2022 12:45:31 GMT 1 sierra3dr said:

Oh,and the "fracture subframe" is due to me being eager with the angle grinder when I changed the front wishbones several years ago,a bolt was not budging because of the corroded thread. I'm still waiting (8 days) for DPD to deliver more exhaust parts   Two more silencers have been added.

I think DPD are listed as being one of the couriers in real trouble right now - they have cancelled their "Next Day" policy for the time-being across the board, but some areas are experiencing 2weeks delay...........

What has happened is that many commercial customers have flipped to DPD (and others) from RoyalMail in the last 4weeks, and they just cannot cope with the unpredicted workload, especially at this time of the year. Add-in the weather conditions, and their warehouses are full to the gunwales, nothing going anywhere.......

[eddypeck]

I don't know how accurate it was but I downloaded an decibel meter app on my iphone.

The reason being I had just bought a 1972 VW Beetle, 1600 on twin carb, J-tubes and so nasty backbox hanging out the back. It was so loud it was horrid.

According to the app, it was 98db whilst driving....  from the passenger seat with the windows closed 
I spend a couple hundred quid on a more sensible exhaust, added some of the tin-wear and seals that were missing and it dropped to 94db

It was a cool car, but my wife refused and kids refused to go in it and my dogs were terrified of it. Needless to say I had to sell it, luckily I made a profit.

I owned it before they moved the MOT exemption on, so I still had to have an MOT on it, no issues .... not noise related anyway.

[huffo]

94dB is very loud for a car. World Health Organisation recommendation for 90dB is no more than 4hrs in 7days.

The decibel scale is logarithmic. The sound pressure on your eardrum at 98dB is about 32% more than at 94dB, so you did well to reduce it that much, and it will have felt like a considerable improvement.

I’m surprised if your Beetle was actually that loud, because my old Land-Rover Series 1 is under 90dB at 50mph, and I consider it to be seriously loud inside, but apparently your Beetle was about 30% louder! I wouldn’t trust my sound meter though….

[eddypeck]

Like I said, no idea how accurate an app on a phone could be so it's fair to assume not very. That said, at least I used the same device to record it before and after, so even if the numbers weren't accurate I at least had a control level to prove it was a reduction.