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What Is The Legal Db Limit For Exhaust In Nsw?

Munkyb0y

By Munkyb0y,
in New South Wales

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GreddyGo Rising Star

GreddyGo

Posted
Posted

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 Grand Master

Munkyb0y

Posted
  • Author
Posted (edited)

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 :laugh:

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 by Munkyb0y
Zane Enthusiast

Zane

Posted
Posted

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.

Munkyb0y Grand Master

Munkyb0y

Posted
  • Author
Posted
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 :laugh:

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

Zane Enthusiast

Zane

Posted
Posted

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.

RellikZephyr Proficient

RellikZephyr

Posted
Posted

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

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