Iso 5103

[feb 47]

Hi,

 

Does anyone know how testing exhaust noise levels is conducted by e.g. police or during a trackday?

 

Cheers!

[johnnyboy666 195 1 Cars]

In my experience police use a technical device known as 'discretion'

 

I'd imagine officials would use a decibel tester thingy?

[BlueBolt 156]

In my experience police use a technical device known as 'discretion'

 

I'd imagine officials would use a decibel tester thingy?

 

Police one is obviously by far the more technically advanced of these tho!! I've seen different readings depending on the operator on previous experience!!

[feb 47]

I have a decibel tester and out of curiosity wanted to measure the noise of my exhausts.

At what distance from the backbox and rpm should I measure?

[Cameron 16]

MSA regs on exhaust noise are - here.

 

You need to make sure you measure in the (A) range on your dB meter, 0.5m -1m above the ground, 0.5m away from the tailpipe at a 45Deg angle to the car centreline. There's a diagram showing this and also a table of the noise levels in the MSA link above.

 

I haven't heard of any dB level being enforced for road cars and I'd be very surprised if the Police had any authority over it, I think the most they can do is send you to an MOT station to have it checked.

[BlueBolt 156]

I haven't heard of any dB level being enforced for road cars and I'd be very surprised if the Police had any authority over it, I think the most they can do is send you to an MOT station to have it checked.

 

I had a copper pull me a few years back when I had my v6 coupe fitted with a 4 inch jap can single silencer system... It was VERY loud!!

He told me that any exhaust system that was louder than standard was illegal...

 

I then went on to ask him about the obvious louder effects of sports cats... He'd not heard of them!!

Or, what about the loudness effect of an induction filter... Again no answer!!

He gave me a producer slip to tell me I had to get it changed... Can't remember exactly what the slip was, but I was getting it changed within the next couple of weeks anyway. He also took the details of the MOT station I took it to as he said the tester needed re training, not been back to that test centre again lol

[Cameron 16]

Well he was full of s*it to be perfectly frank and that's typical Police bulls*it trying to scare people who don't know better with the "I-bomb".

[BlueBolt 156]

I completely agree!! He did seem like a complete jobsworth!!

[cybernck 402 1 Cars]

I once had a copper tell me my Remus backbox produces 154 dB!

[Cameron 16]

That would be impressive.

[feb 47]

Does 101db at ~5,300 rpm seem reasonable?

It is certainly not loud, enough to hear the unequal length headers boxer's burble.

I didn't have a tape measure to confirm distances, roughly by eye, could have been a bit closer than 0.5m

Edited April 16, 2012 by feb

[welshpug 1,657]

that would fail at most UK tracks and I would certainly get pissed off with it myself being that loud!

 

what system is it?

[stu8v 68 1 Cars]

that would fail at most UK tracks and I would certainly get pissed off with it myself being that loud!

 

what system is it?

 

TBH thats not that loud, my old impreza measured about that and was reasonable even on the motorway. Oh that was stripped out interior too.

 

Most trackdays I do are 105 limit

[feb 47]

It's not loud (I can't stand loud exhausts these days - getting old), my 205 on a GrpN system was much much louder!

3" Miltek turbo back with a sports cat and 2 silencers.

I replaced the Miltek backbox with a Sti one that was converted to 3" to match and it is slightly quieter and less droney than before, unfortunately I didn't measure it before.

I thought the limit was 102-105db static on trackdays?

Edited April 16, 2012 by feb

[Cameron 16]

It varies from track to track, a few are 105dB, some are less.

[Anthony 1,003]

I had a copper pull me a few years back when I had my v6 coupe fitted with a 4 inch jap can single silencer system... It was VERY loud!!

He told me that any exhaust system that was louder than standard was illegal...

Well he was full of s*it to be perfectly frank and that's typical Police bulls*it trying to scare people who don't know better with the "I-bomb".

Actually, as far as I'm aware it is an offence under the Construction and Use regulations to have an exhaust that is louder than was originally supplied with the vehicle, and a quick search reveals this which appears to suggest just that:

 

Silencers

54.—(1) Every vehicle propelled by an internal combustion engine shall be fitted with an exhaust system including a silencer and the exhaust gases from the engine shall not escape into the atmosphere without first passing through the silencer.

(2) Every exhaust system and silencer shall be maintained in good and efficient working order and shall not be altered so as to increase the noise made by the escape of exhaust gases.

(3) Instead of complying with paragraph (1) a vehicle may comply with Community Directive 77/212, 81/334, 84/372 or 84/424 or, in the case of a motor cycle other than a moped, 78/1015.

(4) In this regulation “moped” has the meaning given to it in paragraph (5) of Schedule 9.

 

Regulation 58 also appears to imply that cars produced after 1970 are subject to a limit of 85dB, although that doesn't appear to make sense on the face of it when the limit for the then SVA test was 101dB and for the current IVA test it is 99dB AFAIK. I can only assume that dramatically lower limit is either for European type approval for mass produced cars, or is tested in a different manner to the SVA/IVA.

 

Not only that, but an exhaust notably louder than standard should fail an MOT too, but rarely do - straight from the MOT manual section 7.1:

 

4. A silencer in such condition, or of such a type, that the noise emitted from the vehicle is clearly unreasonably above the level expected from a similar vehicle with a standard silencer in average condition.

 

In that regard, the policeman was bang on the money from what I can see and if it was excessively loud then it should have failed the MOT and would be in convention of the Construction and Use regulations. Just because something is rarely enforced doesn't mean that it doesn't exist.

 

I thought the limit was 102-105db static on trackdays?

Depends on the trackday - some (e.g Goodwood) are as low as 95dB.

 

Static tests aren't generally a problem anyway - it's driveby tests that can be far more problematic for turbocharged cars or ones with loud induction. Bedford in particular can be a real headache.

 

(also, static tests seem to be distinctly variable - I've had between 85 and 92dB on the same car/exhaust before now when being sound checked at track days, and 7dB difference should be considerable!)

[chipstick 382 1 Cars]

Many years ago I was pulled over by a police motor bike for having 2 steel wheels and 2 alloy wheels. He asked me to follow him to the station where Vosa would be to check the vehicle over.

 

They picked me due to the visual differences and wanted to look the rest over. I explained to the chap from VOSA that they were steel on the front due to the alloy wheels having low tread. They were fine with this and checked a few more bits over and the police officer stepped back and said 'surely there must be something wrong with it' and started to nose back under the bonnet. I sniggered at his humour to find he was actually being serious.

 

They noise tested my exhaust and I was only 0.5 decibels from where they explained it could be.

 

The VOSA guys were more than friendly throughout and praised a youngster for keeping his car up together but the policeman wasn't so friendly.

 

As it was several years ago now I forget exactly what they 'limit' was or what offence it would be if it was over.

[Cameron 16]

"Shall not be altered", not "shall not be replaced".

 

The wording of these things is incredibly important, as with all rules you need to be sure you interpret them correctly.

[Anthony 1,003]

That's the thing, they are open to interpretation.

 

"Altering" an exhaust system could very well be interpreted to mean replacing it in part or its entirety. It depends whether there is a very specific definition of altered with regards to the C&U regs.

 

Looking at it another way - I wouldn't want to try arguing to a judge that the exhaust system had not been altered when it is blatantly non-standard looking and emitting substantially more noise than standard. It would be akin to arguing with an insurance company that wanted to void your policy for non-disclosure that you hadn't modified the engine from standard as they're accusing because you'd actually swapped it for a bigger one.

 

Regardless of the C&U wording, there is little doubt that excessively loud exhaust do fall foul of the MOT requirements, but fortunately/unfortunately (depending which side of the fence you're on) it seems that most MOT testers either ignore or are very lenient on that particular point.

[m_attt 31 1 Cars]

The police deffinatly have power over it and can carry testing equipment. There has been a big crackdown on it near me. stopping and testing any car with a loud after market exhaust.

[Cameron 16]

Bad time for me to get a Ragazzon for the Alfa then?

[omega 82]

wish they would clamp down on all the chavs/drug dealers round here in there scoobys with there 6 inch tailpipes.

[GLPoomobile 958]

Bad time for me to get a Ragazzon for the Alfa then?

 

Forget Ragazzon. I told you, you need a Wizrdovoz custom system, sold through the AO forum. Much better.

[Daz_C 8 1 Cars]

Me and a mate got stopped at Dover docks coming back into the UK last year, my friend has a Mk1 Astra with an after market exhaust, my issues aside, the copper was a right knob about the exhaust on the Astra saying it was louder than a standard exhaust etc and proceeded to enlighten him on the regulations, in the end my friend asked what the db reading was for his Mk1 Astra and what action he was going to take. The copper didn't know what the db reading should be for said vehicle and that he couldn't take any action other than inform him of the regulations. My short fused mate (after 20mins of arguing with a fair point that if he didn't know what the actual db should be how the hell does he know it's louder than it should be) told the copper to stop waisting his time then, jumped back in his car and drove off.

Presumably VOSA have more enforcement powers than this copper?

 

 

Feb - that engine had a db reading of 95db with the exhaust I had on it at 4000rpm.

Edited April 16, 2012 by Daz_C