Db Exhaust Testing And Nsw Regs

[DECIM8]

Hey peoples,

Couple of questions.

New mods went on and the car is insanely loud which Im really stuggling to understand as the exhaust used to be very silent on idle so much so a police officer never commented. Now Im pretty sure 3 blocks away you'll hear me. so......

What are the legal requirements for Exhaust dB in NSW for a 1998 Skyline?

Secondly where can I get the test done to make sure I'm within these guidelines.

Honestly I dont care to much about the defect I just feel its a pain in the ass when I pull up to peoples cars and my exhaust is so loud you can see the windows shaking on there vehicle, im waking their baby up, or im drowning out the sound of there 10,000$ system.

Oh and I dont particularly want to pay for a defect lol.

So anyone help?

[JAS-25T]

RTA site has all the legalities - This page has the relevant ADR you want for the test and requirements

Also - most good exhaust workshops can give you the read out and build an exhaust to suit your requirements.

[DECIM8]

How hard is it to re-build? Ive got a pricy cat back and dont want its sound or flow decreased, I assume thats not poss. I was concidering a control valve for the exhaust.

I have heard a manual is best like the apexi ecv

So from the attached website you gave me, 79dB moving and 90 stationary? How does that work?

Many thanks for your reply Jas, gave me everything I need.

Edited July 6, 2008 by DECIM8

[JAS-25T]

The test show how they work.

Also - you can get an extra straight through muffler put in which would quieten it down and also not cost a bomb.

Should just be a simple, cut out pipe section and weld in new muffler.

[mark_sudakov]

How hard is it to re-build? Ive got a pricy cat back and dont want its sound or flow decreased, I assume thats not poss. I was concidering a control valve for the exhaust.

I have heard a manual is best like the apexi ecv

So from the attached website you gave me, 79dB moving and 90 stationary? How does that work?

Many thanks for your reply Jas, gave me everything I need.

hmm im in the same position, bought the car like that, seems to be a full 3" xforce system. Ive got the Apexi ecv u mentioned but controller is not hooked up to the valve. I have been wanting to attach it for a while but havent got round to it. But i will in the next couple weeks as i have already been warned by highway patrol.

Dont know how good the ecv is, doesnt sound like its healthy for the car when valve is closed, so im thinking of getting rid of it and going for a Varex muffler, which is the other option. But also abit cautious on how restricted it is, even when fully open, hopefully not much.

In regard to the db level, its something like 90db when revved to 4000 or 4500rpm, cant remember exactly what the police officer told me. Basically, if u get caught and have to do the db test, u will have to weld a silencer so its not removable to pass or mid muffler i guess. If emissions test, then forget it, stock only option. Thats why its best to not get to this stage otherwise it goes downhill fast.

Anyways thats wat i got to say about the issue

[DECIM8]

It has a massive resonator/muffler in it, supposedly meant to qualify with jasma. 96db or somthing. So im not sure how much improvement can be made.

[mark_sudakov]

i think jasma regulate to 91db, which is 1 db over aussie limit. Probably best to check the db level as is, and then go from there. Im going to do this too, i rekon im off my abit

[Taleb Tyres]

i have the same deal as you, and i have the apexi evc, your right its not healthy for the engine, when closed, the gas has nowhere to go but back where it came from, but for short times when you need stealth, or to pass certain tests , works a treat.

I havent tested my exhaust at full volume, but when it was 3/4 closed for a pits inspection, i passed by 0.4 db, just make sure your exhaust has no leaks or you will be able to tell there is something extra in there your not meant to have(its illegal, but when the inspector bent down to check, he pretty much just checked to make sure i had a cat)...

But it sounds like your exhaust is louder than mine, so it would just be a temp fix for certain situations.

[mark_sudakov]

i have the same deal as you, and i have the apexi evc, your right its not healthy for the engine, when closed, the gas has nowhere to go but back where it came from, but for short times when you need stealth, or to pass certain tests , works a treat.

Hey mate,

How does the controller actually work, do u twist it or something to close the valve? How do u know when its 3/4 closed?

[JAS-25T]

i think jasma regulate to 91db, which is 1 db over aussie limit. Probably best to check the db level as is, and then go from there. Im going to do this too, i rekon im off my abit

JASMA is the Japan Automobile Sports Muffler Association - Not a specific db.

They do make them to various db ratings, though none are made to suit our ADR's, if they are only by coincidence.

less noise - more mufflers.

Simple.

Also don't have cannon mufflers if you want quiet.

A good quality exhaust system with good quality mufflers will be quiet AND flow well.

[mark_sudakov]

Also don't have cannon mufflers if you want quiet.

A good quality exhaust system with good quality mufflers will be quiet AND flow well.

I think this is a good option. If i do go the Varex it will be the oval one or twin tip one. Police like to pick on the Cannon mufflers even if they dont sound that loud. Do u by any chance know how restricted the Varex is when completely open? Same as any other muffler?

[JAS-25T]

It will always be restricted by design because it is a buterfly valve.

Not mentioning that they are illegal on the road.

[msnismo]

I found that the exhaust system on my car... it has invidia or something on the tip but Bee*R all underneath it on the mufflers (same co??) .. is quiet enough for the DB stationary test but seems to get significantly louder over 4,000....

Its heavy, has two normal style mufflers, I have installed a metal cat but it doesn't restrict flow..... oh and its 3.5 turbo back... Although the custom dump/front pipe has made it slightly louder again.... so Im prolly going to have to get retested just to check it still passes for the eng cert....

And my engine, manifolds etc are far from stock....

However the zeddles is as loud a mofo with the kakimoto exhaust but never ever gets pulled over... imported under the 15 year rule so has an engineering cert lodged against the rego.... guessing this might be the reason??? That or they have absolutely NFI what it is and just don't bother!!!

btw the test is conducted at 3/4 throttle of your designated redline for your vehicle.... ie where the redline starts on the standard dash.... they call it ESMP or engine speed at max power... so work that out and aim for something thats quiet around that rev range.... or shove a crap load of steel wool in the rear muffler... lol

[Abo Bob]

btw the test is conducted at 3/4 throttle of your designated redline for your vehicle.... ie where the redline starts on the standard dash.... they call it ESMP or engine speed at max power... so work that out and aim for something thats quiet around that rev range.... or shove a crap load of steel wool in the rear muffler... lol

Actually it's 3/4 of the revs where it makes max power when stock.

[JAS-25T]

LMAO @ steel wool.

Just make sure its stuck in well and doesnt burnout before you get to the test. Oh and make sure it doesnt pop out while its getting tested.

Don't ask how I know this.............. lol

[DECIM8]

Sounds like a pain in the ass, Look my mate has a GTR and I thought it was the loudest thing ive ever heard. My car came back and it easily shadows the GTR.

Yes my exhaust is a Kakimoto. Sure they sound sweet but seems once they get some power down them they like to rumble. Its a cannon too.

Alright Ill get her tested, my main concern is idle noise.

Why couldnt I get a 2.5 Butterfly and stick it in the 3.5 exhaust (3" flange) and then run it like that noise would be dropped alot yet it would still flow alot? not constantly I must stress.

I dont want a varex muffler for god sakes its made by xforce we all know how crap x force is

Edited July 6, 2008 by DECIM8

[msnismo]

Actually it's 3/4 of the revs where it makes max power when stock.

ah okies... so its not the first dash parts of the redline?? The tester told me the wrong info.... So guessing the factory specs determine the testing point... all good, I dont have to declare my peak power as 8,200 then!! lol

LMAO @ steel wool.

Just make sure its stuck in well and doesnt burnout before you get to the test. Oh and make sure it doesnt pop out while its getting tested.

Don't ask how I know this.............. lol

bwahahaha Yes I have also experienced this first hand.... expression was priceless... and didn't make the same mistake the second time round..... different tester obviously This was years ago in my S13 for engineering cert.... got round the corner from the second place, jammed it in and rammed it down.... crossed fingers.. lol

My car was spitting it put for about a week later I jammed that much in there.... level prior to steel wool (and secondary muffler) was around 102 db.... whoops... again straight through kakimoto exhaust...

[msnismo]

Sounds like a pain in the ass, Look my mate has a GTR and I thought it was the loudest thing ive ever heard. My car came back and it easily shadows the GTR.

Yes my exhaust is a Kakimoto. Sure they sound sweet but seems once they get some power down them they like to rumble. Its a cannon too.

Alright Ill get her tested, my main concern is idle noise.

Why couldnt I get a 2.5 Butterfly and stick it in the 3.5 exhaust (3" flange) and then run it like that noise would be dropped alot yet it would still flow alot? not constantly I must stress.

I dont want a varex muffler for god sakes its made by xforce we all know how crap x force is

What about a normal shaped Kakitmoto muffler?? I mean mine is loud on the zed and was on the S13 when up it, but at idle it was reasonable and didn't shake cars next to me..... the garage on cold start in a two story townhouse was another matter though... lol

Both of mine ran one normal muffler .... the S13 didnt have a cat either (brought in like this and passed by RTA for first rego....lol) I wasn't aware till I was at the pits (all excited to get it rego'd) and they went under it and I noticed that the cat had been split/gutted and rewelded over the straight through pipe!!! Sensor was still in the cat though... was very well done! several defect pits over 5 years and it wasn't once noticed... although the analyser would of picked it up if they had ever tried it

[JAS-25T]

My Kakimoto exhaust on my old R33 was fine.

Brand is exclusive to volume of noise, it's the type of muffler and specs that are inclusive.

[Abo Bob]

ah okies... so its not the first dash parts of the redline?? The tester told me the wrong info.... So guessing the factory specs determine the testing point... all good, I dont have to declare my peak power as 8,200 then!! lol

Yeah it's one of those things they often get wrong. You have to be insistent and make them read the law again.

I've often wondered if you could just go to a dyno and do something like knock 20 degrees out of your timing, take the dyno printout to the tester and say, "look, peak power at 3500rpm and only 85kw too. db test is at 3/4 of that. "