Decibel Test??

[hogs]

Evening,

Have got a lend of a DB Meter and checked up with the local testing folk to get the correct test protocol.

4500 rpm, at .5 metre on a 45 degree angle, was the feedback I got.

And it has to measure 90 DB or less.

Would like some feedback / info in relation to this along with how much the
LS1 likes being revved at 4500 rpm unloaded.

Cheers,

Hogs,:)

PS Would there be a Harley that would meet this DB reading, and if not why do we have to have more stringent rules applied to our rides and they get away with it on a daily basis????

[Brass Munky]

Last i recall there was something about the harleys that didnt have to comply, and i think it was that, cant remember why, cant even remember who told me, but i dont think they have to comply for some reason

[hadafew2many]

i have had most of my gen 3 cars tested by both police and department of transport. In qld they have a book of db readings and rpms that the certain car should be revved at but all are tested in the same process and in much the same manner you described

[hRTHSV]

Evening,

Have got a lend of a DB Meter and checked up with the local testing folk to get the correct test protocol.

4500 rpm, at .5 metre on a 45 degree angle, was the feedback I got.

And it has to measure 90 DB or less.

Would like some feedback / info in relation to this along with how much the
LS1 likes being revved at 4500 rpm unloaded.

Cheers,

Hogs,:)

PS Would there be a Harley that would meet this DB reading, and if not why do we have to have more stringent rules applied to our rides and they get away with it on a daily basis????

Each car has it's own RPM to be tested. If you work off 75% of the RPM redline you are about right. I have done this test unloaded RPM won't hurt it, just don't hold it their all day. Harleys and all bikes have to also meet noise restrictions. It's 94dB for a bike depending on age. Trucks have dB reading as well.

[hadafew2many]

Last time i was tested it was just me and one officer. He asked me to hold it on 4600rpm as he manually held the db meter!! im sure i held it on 4600rpm or maybe it was 3600rpm!!! To double check me he revved it was i held the db meter and gave him the honest reading (or close to it)

[hogs]

Evening,

Well, done the test today and was interested with the result!

Lets have a little comp here!

224 rwkw's

HM TRI Y's
ESA 2.5 Twin with standard Cats.
ESA performance Mufflers x 2 Front.
ESA Rear Performance Muffler.
Opened up CAT pipes.

Guess the DB's at 4500 following the criteria mentioned above???

Cheers,

Hogs,:)

[matthewfnorbert]

what weighting are using on the db instrument?

[hogs]

Evening,

Why? Does it make a difference?

Cheers,

Hogs,:)

[BennyMac]

How about 92 DB?

[wablacksv8]

around 93db

[BLACKWAGON]

from memory, di filippo told me that their catback twin 2.5 was 94 db with standard headers and cats.

[mustanger]

I know 90 decibells is FA so I would guess 99db......Cheers John

[vuss383]

My money si on 102 db .
So how long do we have to wait for the result & what is the prize for the person who gets it correct . We cant be having a competition without a prize now can we ..

[vyssbeast]

from memory, di filippo told me that their catback twin 2.5 was 94 db with standard headers and cats.

REALLY?? FARK me ... They are fairly quiet with no headers n cats, let alone with abit of volume added by those.

Hmmm i better tread lightly then, i always thought mine was pretty stealth (wanna go louder)

[BLACKWAGON]

mmmm if i remember rite...........mine is cammed, not overly loud tho

[swingtan]

OK, now to throw the spanner in the works.

From memory, anything measured in "dB" must be referenced to something. The decibel is a logarithmic difference between 2 measured levels. So if there is actually a ruling that states a "dB" level without a reference point, then there is no way to measure this level.

Generally speaking, dBm is normally used for "absolute" measurements and references the measured sound to 1mW. You can also measure in dBV, dBr and a few others. The important bit is that plain dB must be referenced to some thing. When you say the exhaust level must not be over 90dB, you are saying it can't be more than 90dB more than something else. It's more likely that the maximum noise level is 90dBm.

The reason all this is important, is that each reference point for dB will give a different result, as the "starting" point is different and as already said, you are measuring the difference. A sound level meter that can switch between different reference points ( gives measurements in dBm, dBr, dBV etc ) will show different meter readings depending on the switch position ( or reference point ).

For any vehicle made after 1/11/1983 the exhaust noise level must not be over 90dBA ( dB Adjusted, or where 0dB = 3.6 picoWatts, or -85dBm) Remember though that dB is a logarithmic measurement, so every 3 dB is double the volume or power. That means that 90dB is twice as loud as 87dB, which is twice as loud at 84dB.

So basically, you need to ensure that the sound level meter you have will give a readout in dBA. So how do the current estimates rate?

If 90dBA is the goal, then 92/93 dBA is twice as loud as it should be, 99dBA is 3 times louder and 102dBA nearly 4 times louder than permitted. Given I have no idea as to what the ESA components are like, I'll guess it's over 90dBA but probably less than 100dBA.

[Wonky]

Remember though that dB is a logarithmic measurement, so every 3 dB is double the volume or power. That means that 90dB is twice as loud as 87dB, which is twice as loud at 84dB.

Oops, sounds like my (30+ years old) memory of physics and the decibel scale has failed me coz it sure sounds like you know what you're talking about Simon. I thought the noise level doubled with every 10dB and was therefore going to guesstimate 100dB.

I had an EH with basically an XU1 motor that about 30 years ago was tested by the EPA at the roadside. Reading was 124dB - it literally screamed! Extractors, twin pipes, one in front of each rear wheel arch and only a hotdog on each. Of course, who knows how accurate the testing was. :confused:

[swingtan]

Oops, sounds like my (30+ years old) memory of physics and the decibel scale has failed me coz it sure sounds like you know what you're talking about Simon. I thought the noise level doubled with every 10dB and was therefore going to guesstimate 100dB.


Great! Now you've got me worried. I was working from memory as well.... Now I'm going to have to go look it up !


OK, looked it up....

http://en.wikipedia.org/wiki/Decibel

"A level difference of ±3 dB is roughly double/half power (equal to a ratio of 1.995)"

[Wonky]

Great! Now you've got me worried. I was working from memory as well.... Now I'm going to have to go look it up !


OK, looked it up....

http://en.wikipedia.org/wiki/Decibel

"A level difference of ±3 dB is roughly double/half power (equal to a ratio of 1.995)"
Now, just to confuse things (I think)......... :D

From http://arts.ucsc.edu/ems/music/tech_background/TE-06/teces_06.html

"If a sound has 10 times the power of a reference (10dB) we hear it as twice as loud. If we merely double the power (3dB), the difference will be just noticeable."

[swingtan]

OK, we were both right :lol:

Yes, 3db is double the power but 10dB sounds 2x louder

[VX2VESS]

Last i recall there was something about the harleys that didnt have to comply, and i think it was that, cant remember why, cant even remember who told me, but i dont think they have to comply for some reason

prob because the pollies like to ride them

[Wonky]

OK, we were both right :lol:

I'll go with that! :thumbsup:

[hogs]

G'day,

Interesting info fellas, the tech I got the Meter from said that the actuall noise doubled for every 3db's?

Anyway, no one gets the Coochy Doll!

106 DB's

As stated, nothing too special about my system, and I would not have thought it to be over the top in terms of overt noise level, but!!!

Will be driving fairly mekely around the populated areas me thinks.

The greatest impact on the noise was the back off after hitting 4500 rpm!
With the auto you do not get this normally even if you take the foot off after a fair old flogging, however, the manual boys on downshifts etc, must get that a fair bit.

Be careful fellas, how many of us would pass such a test if the Troopers decided to get techo?:confused:

Cheers,

Hogs,:)

[ED]

currently searching for some centre mufflers (3") to try and quieten mine down as have been pinged for noise. Went 96 dB at idle and 105dB at test. (3900rpm) is the test level for ls1 cars, accordingly to the friendly officer.

[OLS108]

currently searching for some centre mufflers (3") to try and quieten mine down as have been pinged for noise. Went 96 dB at idle and 105dB at test. (3900rpm) is the test level for ls1 cars, accordingly to the friendly officer.

mine was 3750 when mine was tested, he also said the law is 75% of where your car makes peak power. and mine was 96BD, $75 and 1 point..
i fitted a rear res, and took a drive down to my local police station and the guy came out and had me rev the car to 3750 and it went to 92DB which he said he was happy with because i had made a clear effort to quieten it down.

Dave

[HSVREDSLED]

I have heard many times that stockers struggle to pass the test let alone ANY exhaust upgrades.

[vt350phantom]

PS Would there be a Harley that would meet this DB reading, and if not why do we have to have more stringent rules applied to our rides and they get away with it on a daily basis????

This is what I have wondered for years!!!! There's a piece of sh*t harley that lives near me that comes and goes about 10 times a day and wakes my daughter up all the time. Noisy slow useless pieces of sh*t (i dont like harleys in case you havent noticed :))

[RedR8]

Bikes like Harleys and other similar agricultural machinery (e.g. Buells) get tested at 50% peak power.

As for exhaust mods - any change done to a stock 5.7 or 6.0 system will put it over. Depending what you do will make it worse.

[macca33]

I have heard many times that stockers struggle to pass the test let alone ANY exhaust upgrades.

Absolutely correct there. I'm fairly certain that the VX HSVs actually didn't make it, with the standard HSV system for that model.

This is why the standard exhaust systems sound so lame, as they have to be muffled to this extent these days.

Cheers,

Macca