View Full Version : so my brother brought home a decibel meter tonight...
creeper
10-02-2009, 10:58 PM
sooo we measured my exhaust level. now i've always found it pretty reasonable. the magnaflow catback tames things down. anyway, here's my findings:
the legal exhaust limit level is rediculous! we measured my exhaust by approximate legal specifications. 20 inches away at a 45 degree angle.
at IDLE my exhaust exceeds the legal limit by 1 decibel. from inside the car i can't even hear it. at 4500rpm(legal measurement is done at approximately 3/4 speed of where engine makes peak hp) it measured 126.3 decibels. approximately 8-9 times the legal limit. 5000+ rpm probably would've exceeded the meters range.
that law is rediculous haha. good thing it's not strictly enforced. thought some of you might find it interesting.
Jersey Mike
10-02-2009, 11:32 PM
What was my reading again?
You have headers, ory and an exhaust and you can't hear it inside your car? Either you are deaf, or a liar. Which one?
EchoMirage
10-03-2009, 07:11 AM
bring it by my house next time
TheBandit
10-03-2009, 08:01 AM
What kind of meter are you using?
BigRocsFirebird
10-03-2009, 08:08 AM
You have headers, ory and an exhaust and you can't hear it inside your car? Either you are deaf, or a liar. Which one?
agreed:nod:
WildBillyT
10-03-2009, 09:13 AM
sooo we measured my exhaust level. now i've always found it pretty reasonable. the magnaflow catback tames things down. anyway, here's my findings:
the legal exhaust limit level is rediculous! we measured my exhaust by approximate legal specifications. 20 inches away at a 45 degree angle.
at IDLE my exhaust exceeds the legal limit by 1 decibel. from inside the car i can't even hear it. at 4500rpm(legal measurement is done at approximately 3/4 speed of where engine makes peak hp) it measured 126.3 decibels. approximately 8-9 times the legal limit. 5000+ rpm probably would've exceeded the meters range.
that law is rediculous haha. good thing it's not strictly enforced. thought some of you might find it interesting.
You sure it's 20 inches?
deadtrend1
10-03-2009, 09:20 AM
SAE test procedures is:
The Society of Automotive Engineers (SAE) with an established noise limit of 95-decibels (SAE J1169). Under the SAE standard, a sound meter is placed 20 inches from the exhaust outlet at a 45-degree angle and the engine is revved to three quarters of maximum rated horsepower. The highest decibel reading is then recorded...
sweetbmxrider
10-03-2009, 09:22 AM
maybe 20 feet?
creeper
10-03-2009, 09:37 AM
everything online says the test is done at 20 inches, idkkk. we did 20 feet at first and i was still at 115. then we looked up the actual test online and that's what it said.
You have headers, ory and an exhaust and you can't hear it inside your car? Either you are deaf, or a liar. Which one?
at IDLE my exhaust exceeds the legal limit by 1 decibel. from inside the car i can't even hear it.
at IDLE i can not hear it inside the car. i am neither.
What was my reading again?
115 or something
bring it by my house next time
no point, only reads to 130 decibels, which btw is typically considered the point of pain and hearing loss haha
What kind of meter are you using?
Phonic PAA2
The reason why I called bs is the fact that I could hear my car at idle with just a magnaflow exhaust... Had one there for 2 years or so. :shrug:
creeper
10-03-2009, 10:47 AM
well yeah i mean you can hear it if you're listening, but between the radio, power steering pump, and valvetrain noises, it's not really like wow the exhaust is loud. with the radio off you hear it, but under normal circumstances it's not very noticeable. maybe i'm just used to it.
Knipps
10-03-2009, 12:11 PM
Everyone's forgetting to ask, what kind of decibel meter? I'm sure the quality of the product can affect the results
LTb1ow
10-03-2009, 12:19 PM
everything online says the test is done at 20 inches, idkkk. we did 20 feet at first and i was still at 115. then we looked up the actual test online and that's what it said.
at IDLE i can not hear it inside the car. i am neither.
115 or something
no point, only reads to 130 decibels, which btw is typically considered the point of pain and hearing loss haha
Phonic PAA2
Reading ftw. :wink:
TheBandit
10-03-2009, 12:27 PM
Everyone's forgetting to ask, what kind of decibel meter? I'm sure the quality of the product can affect the results
You mean like post #5 when i asked what meter? lol I crappy walmart meter will read a lot higher than the real numbers.
Knipps
10-03-2009, 12:29 PM
:nod: much like that haha
well yeah i mean you can hear it if you're listening, but between the radio, power steering pump, and valvetrain noises, it's not really like wow the exhaust is loud. with the radio off you hear it, but under normal circumstances it's not very noticeable. maybe i'm just used to it.
If your power steering pump and valve train are louder inside the car than your exhaust setup, its time for some maintenance
creeper
10-03-2009, 12:53 PM
If your power steering pump and valve train are louder inside the car than your exhaust setup, its time for some maintenance
honestly, nothing in the engine bay makes very much noise at all. exhaust just really isn't very loud at all at idle. you can hear the pump so that will be replaced soon, but the minimal amount of valvetrain noise that i have is nothing out of the ordinary.
my original post was a slight exaggeration, you can hear it. my point was just that if that really is the legal limit it is stupidly quiet, and absolutely any aftermarket exhaust greatly exceeds it. really i don't see why everyone thinks longtubes automatically means insanely loud. automatics idle at 550 and through a magnaflow even with longtubes it is very very tame.
FlyingDutchman
10-03-2009, 01:02 PM
how long do you think you'll have that decibel meter, til Oct 17 maybe?
creeper
10-03-2009, 01:34 PM
forever, it belongs to the school aka my brother
jims69camaro
10-03-2009, 02:15 PM
honestly, nothing in the engine bay makes very much noise at all. exhaust just really isn't very loud at all at idle. you can hear the pump so that will be replaced soon, but the minimal amount of valvetrain noise that i have is nothing out of the ordinary.
my original post was a slight exaggeration, you can hear it. my point was just that if that really is the legal limit it is stupidly quiet, and absolutely any aftermarket exhaust greatly exceeds it.
i, for one, found this most entertaining. informative, even. so maybe all of those cops are right and we're wrong? the exhaust really does exceed SAE standards? wow*. just... wow.
really i don't see why everyone thinks longtubes automatically means insanely loud. automatics idle at 550 and through a magnaflow even with longtubes it is very very tame.
but outside of the law, according to your anecdote.
*btw, there is zero sarcasm in my reply. i know it's hard to tell with typed words what the mindset is of the typist, but i can assure you i meant no sarcasm at all.
Jersey Mike
10-03-2009, 03:15 PM
My car is quieter than Keiths, which unless you really get on it isn't very loud. I got pulled over for "loud muffler" a week ago, let off with a warning [knock on wood], but my car only made "115 or something" when we tested it on Keith's db meter (that was at redline too).
creeper
10-04-2009, 12:40 AM
jims69camaro, i really don't understand exactly what it is you're trying to say. when i said i exaggerated, i was saying that it is indeed audible but barely so at a idle. i knew ahead of time my exhaust was illegally loud higher up. what i've been saying about the law being insane is that at IDLE my car exceeds the sound limit for any rpm, and from inside the car it really is barely audible. if anyone cares to dispute this i will gladly let them sit in my car and listen for themself.
at higher rpm my car is loud. very loud. i was expecting it to be illegal, no surprise there.
Savage_Messiah
10-04-2009, 06:28 PM
FWIW, I had my town's cops check through the books, they couldn't find any actual decibel limit
Tru2Chevy
10-04-2009, 06:30 PM
FWIW, I had my town's cops check through the books, they couldn't find any actual decibel limit
I would have to check again to be sure, but IIRC, NJ motor vehicle code specifies the SAE test outlined earlier in this thread to check. I have heard from numerous cops that it is left up to the officers discretion, and this may be due to local ordinances.
- Justin
DaSkinnyGuy
10-04-2009, 08:31 PM
Ive done the dB test about 2 feet behind my car at a 45 degree angle at start up on cold morning it was 100dB
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