How loud is 90dB?

[MonoJoker]

OK folks when booking a skidpan day at Mt Cotton I found out we may be subjected to noise meter readings of our vehicles to ensure they do not exceed 90db. Just how loud is 90dB and how many of our members are likely to pass?

I have Pacey Tri-Ys with std cats and a twin 2.5" system including mufflers and a rear res - would I likely be under 90?

I'm guessing the guys with no rear resonators are going to be well over judging by some of the roars I heard at the Validation/cruise night.

Cheers
LT.

[vycalais5.7]

this may not help but a full revving chainsaw is about 80-90db @ 3 meters away. it is also a very very different sound so my info is most likley useless any way just praticing my typing skills :doh:

[BigJim]

OK folks when booking a skidpan day at Mt Cotton I found out we may be subjected to noise meter readings of our vehicles to ensure they do not exceed 90db. Just how loud is 90dB and how many of our members are likely to pass?

I have Pacey Tri-Ys with std cats and a twin 2.5" system including mufflers and a rear res - would I likely be under 90?

I'm guessing the guys with no rear resonators are going to be well over judging by some of the roars I heard at the Validation/cruise night.

Cheers
LT.


How is it measured. Is it 3m from car reving it to a certain RPMs or is it a full noise when under wot.

My twin 3 inch is not legal now and i dont think it would pass the 90DB but by this stage it will be turboed so should be quieter. Iam going to take it to a guys exhaust shop i know and get it tested this week out of curiosity before i turbo it and ill let you guys know.

If mine passes your should be ok as mine is fairly loud.

Jim

[vyssbeast]

would a twin 2.5" catback (DF) be legal?? i actually find that its quiet or im just used to it i want it louder!!

[darcy]

If it isn't stock, it isn't going to pass a 90dB test they way the DOT measure it.

Depends how they (skidpan ppl) are mesuring the sound.

[kayman]

definatly keeping the stock system when i get mine changed then.

[jneil]

I am sure that Murcott Hi-Po day said just 75db...I was a little worried but they didn't check at all and I have DF 2.5" and Pacie Tri-y's.

Mine isn't loud but going on the factory vaccuum cleaner stock sound, anything louder than a fart would fail the db test!

[pagey]

All will definately pass..

The GT40 passed no sweat.. with this exhaust (no cats) http://www.oz8.org/gallery/albums/Pageys-Gallery/gt40_4.sized.jpg

Their testing method is pretty weak.. essentially you start about 200 mts away drive towards it in 3rd or so at 3000rpm plus (i think - it was a while back). Essentially, you can back off the throttle anyway.. you would be mad to try to be a hero and be at 6000rpm in 1st..lol

Even crazy ricers and a wierd hybrid that was crazy loud got through.. You'll be fine.. Have fun... and watch the corner at the end of the straight.. eeek.

[seldo]

The decibal thing is a bit of a black art. I recall getting done years ago at Amaroo Raceway with an Alfa V6 that, whilst it was loud didn't sound THAT loud compared with the ear-splitting shriek of the 13b PP Mazdas. They came in at 90+ :nopity: and I was 106....:shock:, but you'd have sworn it was the other way around. So, just because you think it isn't that loud doesn't mean that the measuring device won't fail you....

[Satansfist]

The decibal thing is a bit of a black art. I recall getting done years ago at Amaroo Raceway with an Alfa V6 that, whilst it was loud didn't sound THAT loud compared with the ear-splitting shriek of the 13b PP Mazdas. They came in at 90+ :nopity: and I was 106....:shock:, but you'd have sworn it was the other way around. So, just because you think it isn't that loud doesn't mean that the measuring device won't fail you....

That's the difference between the perception of sound and measuring the volume. It's why a high revving mini-bike is a pain in the ass and an open piped Ducati is a dream. Usually to measure, the audiometer is placed a fixed distance from the exhaust pipe (3 meteres I think) at a 45 degree angle and the vehicle is revved to half of maximum rpm. Decibel readings are on a logarithmic scale so values go up pretty quickly at the top end of the volume scale, an increase of 10dB is approximate to a doubling in loudness.

80dB is the sound of a vacuum cleaner, 100dB is the maximum volume of your iPod blaring in your ear. 130dB is the threshold of pain, 140 is an F-18 taking off.

[lumpdog]

90 db is a budgie farting

[alto]

my induction noise is louder than 90

[Azza]

Some "factory" exhausts from HSV have been measured louder than 90db and their ment to conform to ADR to sell the car.

There's the same rule of 95db at WSID for street meets and couple of the cars when I've attended, you would swear they were louder than 95db at idle but have never heard of anyone been asked to leave because the car is too loud.(Not saying it hasn't happen either)

They must have to put that clause in their rules to make the EPA/OH&S happy.

It just another way for big brother to ruin our fun :banana:

[SLEEPERVX]

Monojoker - Did the organisers of the skid pan day/night let you know exactly how they tested the exhaust noise? If, like Pagey said, they do a drive by at 3000rpm, then most exhausts would be fine.

[nudenut]

Decibel readings are on a logarithmic scale so values go up pretty quickly at the top end of the volume scale, an increase of 10dB is approximate to a doubling in loudness.
Doubling actually makes roughly a 3dB difference ...

[VXSS346]

Doubling actually makes roughly a 3dB difference ...

I think doubling loudness to our ears is 10db, but a 3db rise equates to an electrical power (Watts) doubling.

[VX2VESS]

mines 80 db idle and over 100 at 2,000 rpm using the epa measurement. twin 2.5's

ooops thought it was a new thread, but i was still in search mode, sorry it is old