Noisy exhaust tests coming

[VR-4Squid]

so, how long until someone has copies of the sticker for sale on trademe

[XSVWGN]

i remember when they tried to inforce the Exhaust laws a couple of years ago. They hit wellington on a friday and saturday night. All vehicles "too loud" were Green Stickered. Was bullshit. I must admit when im heading home after work through town there are always some cars that are so loud it gives you that ear peircing sound!!!

[barryogen]

it's good to see some clarity(compared to the current boyracer law).

95dB is certainly "loud enough" to fit all but the biggest of idiots on the road, personally I'd have liked to see 90dB, but hey, 95 is better than some.


Again, it would be interesting to see how the Harleys(105dB from factory on a lot of them), and the bigger Fords and Holdens.

[Quint]

Hmm another problem is 90% of people don't know how loud 95db is, me being one I know that the decibel scale isn't linear and it gets quite exponential towards the higher degrees, but other than that. *shrug*

Anyone know of any comparrisons between db and engine?
Eg. straight 6, 3L, 3" exhuast = ?db

[snwtoy]

Hmm another problem is 90% of people don't know how loud 95db is, me being one I know that the decibel scale isn't linear and it gets quite exponential towards the higher degrees, but other than that. *shrug*

Anyone know of any comparrisons between db and engine?
Eg. straight 6, 3L, 3" exhuast = ?db

There's zero correlation between engine size and noise. A 10cc lawnmower can be louder than a 4000cc V8. It's all to do with the exhaust and mufflers.

And, 95dB does not always equal 95dB - the environment can have a large part to pay. Theoretically your exhaust is louder on a day with high pressure than on a day with low pressure (I think that's the right way round). It's all do do with the density of the air.
Also, any walls, the type of ground (grass/dirt/concrete) etc all have an effect.

[VR-4Squid]

Hmm another problem is 90% of people don't know how loud 95db is, me being one I know that the decibel scale isn't linear and it gets quite exponential towards the higher degrees, but other than that. *shrug*

Anyone know of any comparrisons between db and engine?
Eg. straight 6, 3L, 3" exhuast = ?db

There's zero correlation between engine size and noise. A 10cc lawnmower can be louder than a 4000cc V8. It's all to do with the exhaust and mufflers.

And, 95dB does not always equal 95dB - the environment can have a large part to pay. Theoretically your exhaust is louder on a day with high pressure than on a day with low pressure (I think that's the right way round). It's all do do with the density of the air.
Also, any walls, the type of ground (grass/dirt/concrete) etc all have an effect.

more important even than that, is the distance from the exhaust it's measured at.

[Dragger_Dan]

Should hold the Db Meter on the inlet

Damn, I'd fail

Anywho, you have to think of noisy exhaust's from a good point of view - they let people know you're coming, so you aren't gonna run them over. Also good for reducing the road toll of family pets and possums.

[Pelo]

[barryogen]

more important even than that, is the distance from the exhaust it's measured at.

hence the iso standard...
50cm behind and to the outside of the car from the exhaust tip... so if your tip point towards the metre, expect a higher reading.

the thing I want to know is, what happens with twin exhausts? do they test both sides? do they charge you twice as much? I'm going this route for looks(yep, ricey reason I guess) a for a bit better flow without the look of being a "boyracer".

[Stealer Of Souls]

My only real gripe is that they still won't let people use alternative exhaust control methods...

I personally haven't seen them, but I know people who have. But a number of euro cars now have valve systems in the exhaust which restrict the flow during cruise in order to reduce the noise output.
If they let people retro fit these sort of things
http://www.hyperflow.com.au/techaes.html
then it won't be so bad.

[Mr Revhead]

personally haven't seen them, but I know people who have. But a number of euro cars now have valve systems in the exhaust which restrict the flow during cruise in order to reduce the noise output

i bet you have seen them

ae101 4ages use them, also i think soarers? some thing like that has it

[Silent Knight]

also i think soarers? some thing like that has it

Not as far as I am aware of bubba...

[Mr Revhead]

its something large and overweight like a soarer then, one of the chasers maybe?

[Silent Knight]

Could be one of the JZX100s or Aristos...

[peas]

There's zero correlation between engine size and noise. A 10cc lawnmower can be louder than a 4000cc V8. It's all to do with the exhaust and mufflers.

And, 95dB does not always equal 95dB - the environment can have a large part to pay. Theoretically your exhaust is louder on a day with high pressure than on a day with low pressure (I think that's the right way round). It's all do do with the density of the air.
Also, any walls, the type of ground (grass/dirt/concrete) etc all have an effect.

So by going out at night (typically colder) they will be getting lower readings... good for the borderline people I imagine that the cost of it is partly to recover the cost of the equipment, inspectors time, and partial deterent. Personally I would be happy if my car was not so noisy but its seems to be a struggle with 4A-GEs... hopefully the turbo helps shut it up. Something need to be done but once again the Government seems to have thrown something out there hoping that it might work and worry about the bugs later.

[Mr Revhead]

ah but cooler air transmits sound better and further.....

[Stealer Of Souls]

personally haven't seen them, but I know people who have. But a number of euro cars now have valve systems in the exhaust which restrict the flow during cruise in order to reduce the noise output

i bet you have seen them
ae101 4ages use them, also i think soarers? some thing like that has it

Really! You learn something new every day. Where abouts on the 101 exhaust system are they? I'd like to have a look at one sometime...

[Mr Revhead]

where the exhausts splits to go to the seperate mufflers theres a valve.
at low flow the gases go to the drivers side muffler
when u nail it the l/h one opens up.

thats why on a cold day you can see the gases coming out of one side only

[Stealer Of Souls]

where the exhausts splits to go to the seperate mufflers theres a valve.
at low flow the gases go to the drivers side muffler
when u nail it the l/h one opens up.
thats why on a cold day you can see the gases coming out of one side only

AMAZING! Well, that's my learning for the day done. Time to sleep... Anyone got a 101 I can look at? Or perhaps someone's changing their exhaust and getting rid of that valve? ....

[sergei]

hmm, when I had my AE101 exhaust cut up, I have not seen any valves what so ever, unless they are inside of the muffler.
As for gas flowing different directions is (i think) due to mufler flow differences....