"Noisy" exhausts

[carbore]

Hi,

I have seen various things in the press this week about clamp downs on boy racers including "Noisy Exhausts" often threats of "crushed cars" are banded around. Whilst im not condoning antisocial and dangerous "Chav" driving I think the noise issue is a bit vague.

For example if I drove my Elise (which is race setup) home form an event and happened to drive through "Operation Chav Hunt" there is a chance it could be deemed Noisy, as Im sure will many of our off-road vehicles, especially anything comp tuned.

Now as far as I know there is no specific noise level that a car has to hit, I have never been noise tested in an MOT so surely the legality of impounding a noisy car is questionable when you can not specify in measuarable terms what noisy is?.

I am fairly confident that a "popper copper" would take an objective view and let an insured, taxed, sensibly driven car go on its way, but we live in a time when things like this get outsourced to target based revenue earning bureaucrats and their minions, so I think it bears consideration.

Like it or not, should noise test level be specificed and part of MOTs? , its easy to test as I get noise tested every race meet I do.

What do you think?

[Yoshi]

I think this is more aimed at those who have the specific exhaust systems that make them noisy as opposed to those whose vehicles are standard (am including tuning as a standard thing as you dont replace the parts to specifically make it noisy).

[V8MoneyPit]

For example if I drove my Elise (which is race setup) home form an event and happened to drive through "Operation Chav Hunt" there is a chance it could be deemed Noisy, as Im sure will many of our off-road vehicles, especially anything comp tuned.

In your case, it is hard to believe your car would be deemed 'noisy'. The regulations for race cars are quite strict at most circuits as you will be aware. In my day, we were allowed 120db at 0.5m/45 degrees from the tailpipe. I would start the season with a fresh silencer and by the last event it would be running at 118db! I know it is far less these days.

The other thing is that you will be driving your Elise sensibly on the road, not revving the wotsits off it, so the noise shouldn't be an issue.

In the matter of whether we *should* have defined noise limits.... well, my old V8 would probably fail straight away! As would the old race car (if it ever sees the light of day again!). But I never drove around in the early hours trying to leave the longest black lines along the High Street. That is where the problem is. Not specifically in the noise emitted from the car.

[Evilgoat]

I think theres a difference between the sort of system you have, and the dustbins found on many corsa, clios and saxos.

I'm guessing yours is like mine. Only gets loud when you are giving it beans or are in the 'power band' of then engine.

Rather than the godawful noise a 1.0 Nova makes with a 4" bore exhaust running like a bag of spanners because of the loss of backpressure.

[burgerman]

Rather than the godawful noise a 1.0 Nova makes with a 4" bore exhaust running like a bag of spanners because of the loss of backpressure.[/quote]    

    Fantastic :D   Where do i get one for mine ??  :lol:  :lol:

  Your quite right tough, My V8  Disco trundles along quite discreetly until i can afford to press the go pedal  :twisted: then it "comes alive"

 
I personally have no issues with a specific noise level/test , at random or mot, as long as its sensible, Lets face it most modern Sports saloon cars have a "fruity " note to them

[V8MoneyPit]

Rather than the godawful noise a 1.0 Nova makes with a 4" bore exhaust running like a bag of spanners because of the loss of backpressure.

I find them hilarious. The noise just shows everyone that it's only a puny 1.0 under the bonnet becasue it advertises how slow they accelerate  :lol:

[Bush Tucker Man]

Curious fact regarding Exhaust Noise regulations in another country, but some of you bookworms may know it already


The TVR Griffith is banned from being sold, or registered, in Switzerland as it's too noisy!!!!

How could even they ban such a glorious sound?

[The Ant Hill Mob]

These boys are very silly.  Basic physics states that noise is a form of energy.  That energy has to come from somewhere, and if your car sounds like a bag of spanners and it's got anything less than a 3-litre engine under it's bonnet, you're going to be losing a couple of horsepower going down the street sounding like you've go no exhaust at all.

Silly little boys.  When will they learn there's no substitute for cubes?

[Lord Shagg-Pyle]

The Good Book says
"No motor vehicle shall be used on a road in a manner which causes any excessive noise which could have ben avoided by reasonable care of the driver"
Regulation 97 Construction and Use regs 1986.

Interpret that how you want.
I have issued tickets for making tyres squeal, loud music, revving of stupid bean can exhausts etc etc. I have to say that I usually take action after a warning has been ignored.
Again the recent topic of seizure of vehicles can come into play.

[Bulli]

These boys are very silly.  Basic physics states that noise is a form of energy.  That energy has to come from somewhere, and if your car sounds like a bag of spanners and it's got anything less than a 3-litre engine under it's bonnet, you're going to be losing a couple of horsepower going down the street sounding like you've go no exhaust at all.

Silly little boys.  When will they learn there's no substitute for cubes?

sorry mate but you are way wide of the mark with that. The reason young driver have small engined cars is not because they want them, its because they cant insure large engined cars.
yes noise may be a bi-product of the combustion cycle but to a point a free flowing exhaust system increases power rather than wasting it as you seem to think. I think you will find there are some modestly(under 2l) engined cars that fly. Let alone the performance that can be gained from a 1000cc bike engine, which massively benefits from a free flowing exhaust.ps my 1277cc bike makes over 170bhp at the wheel...way more than my 3.5l v8.......

[lambert]

That said the 170 of the bike does not have to push the better part of two tonne about. :D
 
As to free flow that is true to a point but the point here is extremes and by definition too much of owt is just that. :D

[Bulli]

just what does that have to do with it?

it makes more torque than a golf gti aswell.....

im not saying that load exhausts are better im simply pointing out the flaw in the load exhausts reduce power theory....

oh and on bikes i firmly believe that load pipes save lives!!

[Ja1983]

i suspect the main aim is to reduce the small engined cars that appaer to have driven over a bucket... namely by the noise on a par with an elephant farting down a megaphone, and the aforementioned bucket clinging onto the rear bumper with string.... remains of a mop perhaps?

i fi was woken in the early hours by a bucket back corsa, with less than 4 cylinders under the bonnet, i`d be cross... if i was woken by a large V8 at full chat with a full 3" stainless i`d be much less inclined to throw a half charlie at it.
I do know of a lancia delta HF integrale 16 with a huge turbo which is under order of the council to be switched off and rolled down the street where it lives as people were complaining of picture falling off walls etc.... so fair dos really, i`ve been stood nearby when its idling and struggle to hear the person next to me speak.. hell of a motor tho!

[GREENI]

I had a Clio V6 with a Quicksiler OMG exhaust, OMG stood for Oh My God, I was warned about having one as they boom in side the cab, and were particularly noisy...
I thought, well I've had Westfields and SD1's with side exit exhausts, it wont be that bad...£500 later...Oh My God !!!!!
We went from home to Pembrey Race circuit, and the wife and I 'had' to wear ear plugs...
It made it drive a little better, and from the outside it sounded awesome...
It spoilt the car for me

[Bush Tucker Man]

Your quite right tough, My V8  Disco trundles along quite discreetly until i can afford to press the go pedal  :twisted: then it "comes alive"

Just like the gorgeous 'burble' of a big Yank V8??

 

I personally have no issues with a specific noise level/test , at random or mot, as long as its sensible, Lets face it most modern Sports saloon cars have a "fruity " note to them

Like the Astons, with the (factory-fitted) 'bypass valve' in the system?? :lol:

[Boggert]

The Good Book says
"No motor vehicle shall be used on a road in a manner which causes any excessive noise which could have ben avoided by reasonable care of the driver"
Regulation 97 Construction and Use regs 1986.

Interpret that how you want.
I have issued tickets for making tyres squeal, loud music, revving of stupid bean can exhausts etc etc. I have to say that I usually take action after a warning has been ignored.
Again the recent topic of seizure of vehicles can come into play.

Agghh that will be the good old section 59, I guess. Distress, Alarm and Annoyance.

[carbore]

With regard to a few points (as its late and iv hit the booze)

Free flowing exhaust is hard to quantify, i bet most of the boy racer crap reduces power as it removes appropriate back pressure and is of poor quality. That said my full oversize stainless on the Elise makes it rather nippy, though some poeple have crap loud, exhausts on Elises and then whinge at track days when they fail the sound check

I used to have a scooby turbo years ago (beofre they fell into the wrong hands) some of the blokes in the club had really loud droning exhausts that surley cant have been good.

As people have siad TVR's leave (or rather left) the factory rather noisy so from a point of law surley noisy has to be quantified.

Dont bike exhausts have to be EU marked or something?

Finally I trust "propper coppers" but years go speeding tickets were given out by "propper coppers" who made decisions based on judgment and experience, now we have "traffic agents" with targets combing the roads and machines giving out tickets (by email next im sure)

So the topic is more about whats around the corner and "I diddnt stick up for such and such becuase im not a such and such, then its your turn and there is no one left to sick up for you!"

[Bulli]

Dont bike exhausts have to be EU marked or something?

"

they have to be stamped with the bs kitemark....but strangely for the mot the volume is up tp the testers discretion!!

oh and mine hasnt got a stamp and its been on the bike years. Its relatively quiet a the revs you go throught towns and villages at.

[Lord Shagg-Pyle]

surely it is a case of everything in moderation? My old Mini used to have a straight through 2" bore single box system on it. It went like stink and howled like a demon, but, I drove it in such a way that I didn't cause annoyance to people that lived nearby.
I don't have a problem with 'performance'(?) exhausts, apart from when the local Chavalry decide to do their charge past my house at 2.00am, then I get hacked off.
If they want to rev the guts out of it and make noise, then go to a 'run wot U brung' day and thrash it (and hopefully pop a couple of pistons).
They sooner they work out that the wider the exit aperture on the exhaust is not directly linked to [wee john thomas] size, they'll be far better off.

[Bush Tucker Man]

As people have siad TVR's leave (or rather left) the factory rather noisy so from a point of law surley noisy has to be quantified.

Yes, but TVR had a 'different attitude' to the regulations apparantly.
Do you remember Clarkson testing the Sagaris(?) & saying that when he asked about the lack of ABS, after EEC law stated that ALL new cars are to be fitted with it saying the factory had told him; "Erm.. don't think we got that memo!"
They could be Italian, or French, with thoughts like that :lol:

Dont bike exhausts have to be EU marked or something?

Yes, they do, & they get pulled for them.
There's a bikers cafe that I call at quite a lot when I'm out riding around & occasionally there'll be a Traffic Car (& a couple of bikes) parked nearby, 'checking things out'

Finally I trust "propper coppers" but years go speeding tickets were given out by "propper coppers" who made decisions based on judgment and experience,

There's still some about, or there are up here.
I see a few where I work & they're prepared to use discretion if appropriate.
If it's a safety related issue, poor driving standard, vehicle maintance, sheer stupidity, let alone a blatent offence, they'll act accordingly.

Obviously the stopped riders/drivers attitude counts strongly towards any degree of discretion adopted

[Bulli]

BTM , you are far more likely to get a tug for a dark visor( they make it far safer at this time of the year) and small number plate.

to make the assumption that the bikes had been pulled over, if indeed they had, due to the exhaust volume is a heck of a leap of faith.

squires has always been a biker haunt and quite often has a few hundered bikes and a police presence. I go loads and have never had any issues...

[Terranosaurus]

All this talk of back pressure is a bit old hat, what you're actually searching for is a tuned length, as any 2 stroke biker will surely agree. The manifold design and positioning of the first silencer is the critical thing the system after that does have an effect but the really important bit is that first length.

Now back to the chavs - the problem I think comes from the turbo culture, with a turbo tuned lengths are hyper difficult to achieve and don't really have much of an effect, so you can just run the biggest possible pipe to shift the exhaust gases as fast a possible, so chavs see Scoobys and Evos running round with 4"+ systems and think well if its good for 600bhp on that it must be good for my 106/saxo/corsa/baked bean can.

As for competition exhausts if need be a good competition exhaust will be made to be quite at the test RPM, its a static test at most events and to hell with the rest of the time let it do its own thing. A Mk2 escort I used to own ws quite a sa mouse on part throttle at 5000rpm.

[Bush Tucker Man]

BTM , you are far more likely to get a tug for a dark visor( they make it far safer at this time of the year) and small number plate.

I was merely alluding to the fact that there is a presence there at times & although 'you' may be stopped for visor/plate, I guess that a 'loud' exhaust may be 'looked at'

Yes, I agree with the 'Loud Pipes Save Lives' campaign, but not for 2-strokes & chav-cars

[Bulli]

not for 2 stroke scooters but i love an rgv on song but not in town

[Range Rover Blues]

All this talk of back pressure is a bit old hat, what you're actually searching for is a tuned length, as any 2 stroke biker will surely agree. The manifold design and positioning of the first silencer is the critical thing the system after that does have an effect but the really important bit is that first length.

Now back to the chavs - the problem I think comes from the turbo culture, with a turbo tuned lengths are hyper difficult to achieve and don't really have much of an effect, so you can just run the biggest possible pipe to shift the exhaust gases as fast a possible, so chavs see Scoobys and Evos running round with 4"+ systems and think well if its good for 600bhp on that it must be good for my 106/saxo/corsa/baked bean can.

Which is more or less what the wife was illuding to:

These boys are very silly.  Basic physics states that noise is a form of energy.  That energy has to come from somewhere, and if your car sounds like a bag of spanners and it's got anything less than a 3-litre engine under it's bonnet, you're going to be losing a couple of horsepower going down the street sounding like you've go no exhaust at all.

But my personal pet-hate is the "just backed over a dustbin" look they all seem to crave.  I've seen a Coarser in Dronfield with 4 stainless cans under the back hovercraft skirt that were about the size of the pedal bin in our bathroom.

[Bush Tucker Man]

squires has always been a biker haunt and quite often has a few hundered bikes and a police presence. I go loads and have never had any issues...

Didn't go out on bike yesterday, but might end up there this afternoon at some point (in passing)

[glaggs]

2stroke and 4 stroke exhausts have slightly different jobs to do. Two strokes are much more dependant on back pressure for various reasons, but mainlt to stop the fresh charge making its way out of the exhaust ports too soon and by-passing the combustion cycle! Interestingly reading my'Four Stroke Performance Tuning' Manuel (by A. Graham Bell and published by Haynes) any back pressure will actually reduce bhp, the ideal set up being a tuned length of straight through pipe with as few bends as posible. For ultimat bhp diameter and pipe length are crucial, but back pressure will reduce power on a 4 stroke engin.

This is a simplified explanation of one of the black arts of engin tuning!

ps. I run a 1200bandit putting out 150bhp+ which I did all tuning work my self. The exhaust ia full race Akrapovic titanium system which is suprisingly quiet at every day speeds bu effing loud on full chat. I guess this is down to quality construction and it being a properly tuned system designed to release power not turn it into noise!

[Range Rover Blues]

A lot of people are confusing back pressure with port velocity.  The exhaust gasses help scavenge the exhaust and if you look hard at most cylinder heads the exhaust port widens as it leaves the valve.

The flow of gasses is a very complex issue, partuclualry as it is not even a continuous flow, but pulsed.

A tuned sports pipe will almost certainly be focused on a narrow rev-band with the view to optomising the engine's performance at that speed whereas most road systems make compromises to get a fair performace over a wider band.  Driveability.

BTW anyone else noticed that performance often comes with an increase in the engine's top speed? so again the ability to breath is important.

[Eeyore]

Gotta agree with above.

Also, good flow doesn't have to equal noise.

What it may indicate however, are the compromises needed to be taken to achieve that flow.

Cheers
 8)
Eeyore

[Evilgoat]

What needs to be made clear is theres a difference between £700+ of tuned, professionaly built sports exhaust on a car (les son a bike but not much) which is loud because its doing its job...




And a Mahoosive backbox slapped on a 1.0 engine and the stock exhaust system. you know 1" in, 12" out. I've actually seen a standard 206 with 8 5" pipes before now.