What Is The Legal Db Limit For Exhaust In Nsw?

[Munkyb0y]

My exhaust is too loud for my liking.

I'm getting a resonator put on tomorrow, to quieten it down, and i need to know what the legal dB limit is.

And how do you measure it? eg, 90dB's at 3500rpms?

[Moanie]

its 90db at 4800rpm

[Munkyb0y]

thanks

is that it? just at one rpm level?

[Moanie]

Yeap.. they put a mike to your exhaust.. pull out a db meter and rev to 4800 in neutral and voila!

[Munkyb0y]

cool. will test it tomorrow

thanks.

[Moanie]

no worries!!!

[JAS-25T]

Try the RTA website for full details on teh available tests

as there is also one for drive by testing

[GreddyGo]

I don't think it's as easy as holding it a 4800, they measure when you back off from that so incase it backfires and getting to that RPM, I have done ir before at work for a blue slip and tafe.

They also test starting your car

Cheers

Josh

[Munkyb0y]

ok, so i'll have the dB meter going from start up, to 4800rpm, and back down. if it doesnt crack 90dB it should be fine.

[NBP]

it probably will...

when i got tested i was told to hold at 4000rpm while they stood 1.5m away and at 45 degree angle i also got told it was 96db for me limit wise

[Moanie]

why would it be 96db? have the standards changed?

[Munkyb0y]

faaaarken hell. my exhaust is 102dB WTF???

i held 3500, then held 4800, then back down. the highest reading was 102db.

and to make things worse, we couldnt fit the oval resonator on, coz there's not enough room under there.

that would have only brought it down maybe 3dB anyway. but the only option is to put a hotdog resonator which will only reduce it by maybe 1 or 2 dB.

dangnamit

the way he measured it was 45degrees left of the tailpipe, about 1metre away. is it possible he was too close? i might go somewhere else and get a reading.

edit:

before my highflow cat, the exhaust didnt seem this loud. i assume the cat has increased flow dramatically, causing increased volume.

i didnt expect it. is this pretty normal of a highflow cat? it's only an xforce 3 inch cat (replaced a standard compliance cat).

Edited December 22, 2006 by Munkyb0y

[Zane]

I had my exhaust tested a few years back and I'm sure things haven't changed much.

The process back then was:

Place the microphone at 45deg and 0.5m from the end of tailpipe.

Increase revs gradually to 75% of max hp of engine (this turned out to be 4200rpm for a skyline (any model skyline??) as indicated in the EPA manual, I didn't argue for a more accurate figure because more revs = more noise). Increase in revs has to be gradual so the reading does not spike, otherwise they have to start again. Same goes for backing off. They are not measuring dB under acceleration, they are measuring a simulated drive by situation at constant engine revs.

This process was repeated exactly when I fixed the exhaust and was retested.

I'm running a 3" front pipe off the standard dump, 3" high flow CAT, into 3" pipe with a hotdog inline with a small box resonator, and a 6" barrell muffler with a 4" tip. Tested at 89dB.

Without the box resonator I was tested (and fined) at 92dB. A hotdog will only knock off 1-2 dB. NSW EPA regulation is a maximum reading of 90dB.

Z.

[MYSTR33]

90db at 3/4 of ur rev limit

[Zane]

Yeh, they make the assumption that power is linear. How clever are these guys!!! Must have been the easiest way to work out a standard for all cars.

[Munkyb0y]

I had my exhaust tested a few years back and I'm sure things haven't changed much.

The process back then was:

Place the microphone at 45deg and 0.5m from the end of tailpipe.

Increase revs gradually to 75% of max hp of engine (this turned out to be 4200rpm for a skyline (any model skyline??) as indicated in the EPA manual, I didn't argue for a more accurate figure because more revs = more noise). Increase in revs has to be gradual so the reading does not spike, otherwise they have to start again. Same goes for backing off. They are not measuring dB under acceleration, they are measuring a simulated drive by situation at constant engine revs.

This process was repeated exactly when I fixed the exhaust and was retested.

I'm running a 3" front pipe off the standard dump, 3" high flow CAT, into 3" pipe with a hotdog inline with a small box resonator, and a 6" barrell muffler with a 4" tip. Tested at 89dB.

Without the box resonator I was tested (and fined) at 92dB. A hotdog will only knock off 1-2 dB. NSW EPA regulation is a maximum reading of 90dB.

Z.

i'm running the exact same setup as you, minus the box resonator and hotdog. where the hell did u get the box to fit? if i put it on, it would be hanging way too low, or touching the tailshaft. mine is all mandrel bend, so it kinda takes up alot of room with no harsh bends.

i reckon maybe this guy got the reading wrong, coz the revs didnt increase gradually, i remember punching it a little between 3500 and 4800, coz i was using my left foot, and was only half in the car

although it would still be over legal limit, i have no doubt.

[Zane]

The hotdog and the box resonator only have about 3 inches of pipe between them and they fit between the CAT and the bend before the diff. The box is about 25cm x 20cm so is pretty small. All my pipes are mandrell bent and I had it made to sit as close to the body as possible so I have max ground clearance.

If your over 100dB you may need to look at a bigger rear muffler as well.

[Munkyb0y]

my cannon is 3inch in, 6 inch body, 4 inch out.

but i reckon he may have got an incorrect reading, as i said, wasnt smooth rev building.

[RellikZephyr]

The Ruling is...

Passenger Vehicles Made:

Before March 1985 96 dB

After March 1985 90 dB

R33 GTST

Engine Test Speed 4800 Rpm

Microphone placement

45 Degrees angle +/- 10 degrees

same hieght as exhaust tip +/- 25mm

distance from outlet 525mm +/- 25mm

This info taken straight from EPA and Testing Procedure Manuals

can post em up if you want...

Cheers

RellikZephyr

[Munkyb0y]

is this standard australia wide?