Exhaust db's
 

Any idea on how many db's the stock puts out? Wanting to purchase Nismo, but trying to get an idea on how much louder it is. I think I seen somewhere that the ingen ses was around 90 db's or something.

whats a db? :P

Months ago when we all got together and dyno'ed and also had a sound pressure meeter...

the Stock exhaust was somewhere around 103dB on the dyno...

the NISMO was somewhere around 109dB


the thread is somewhere... ill go find it :)

That has to be off. The law in CA right now is 95 db and I do not think an stock car would be out doing that.

Was the dyno indoors? Maybe the sound was amplified from being indoors ?

Those numbers can't be right Jason. They're way over the legal limit here. My old race car from years ago was only 111 and you could hear it from a few blocks away.

I fart at 120db.

The Nismo Exhaust is not (officially) available in the UK, as it did not pass the homologation tests prior to its release...

Here is information received from Nissan Motors Great Britain regarding the noise levels of the 350Z with both stock & Nismo exhaust

As part of the European homologation testing, the vehicle had to undergo a drive-by noise test. The Nismo Stainless Steel Exhaust result of 89DB was above the maximum allowable level of 75DB. For information, the standard 350Z exhaust drive-by noise is 73DB

The numbers according to the Sport Z Exhaust Shootout are:

First number is @ idle, second @ 3K rpm
OEM: 81db / 89db
Borla: 88db / 92db
NISMO: 84db / 95db
Stillen: 84db / 93db
Injen: 83 db/ 99db
5Zigen: 87db / 105db

What's interesting about the European Homo test is how quiet they claim the stock Z exhaust is. In the numbers above the NISMO is 3/6 db higher than stock. Every 3db is twice as loud and I can attest that the NISMO at 3K is a lot louder than stock. The Euro Homo test claims that the NISMO is 16db louder? Makes me wonder if the Z's delivered in the UK have a different, quieter exhaust than the US version.

I just had my car measured outside at full throttle on a straight away, redlining at 87db. This was measured 8 times and it never got any higher than 87db.

I have NISMO exhaust and a pop charger. By the way, you will never hear a sweeter sounding car under full throttle! (IMHO)

Hey Jason, looks like no one got your "db" joke. Everyone's still saying it.

Bear in mind that the European Homologation Tests are for the DRIVE BY noise level, so this would explain the lower figures...

Prior to the UK Launch, one of the senior members of the Product Team at Nissan Motors Great Britain told me that the engine tuning setup for Europe is (officially) as per Japan, but with the an Oil Cooler added (for autobahn driving), however the exhaust is as per the US 350Z... so go figure

It all depends on the distance of the dB meter. The exhaust shootout reading were taken at 20ft (center of exhaust tips) if I remember correctly. If you get busted in CA for noise they test your car at 50ft (center of exhaust tips).

It's very wordy... but here are the conditions resulting in the UK reading...

Bear in mind that the Nismo Exhaust only failed on the Drive By - 3rd gear etc. & not on the stationary test

I.3. Conditions of measurement
Measurements shall be made on unladen vehicles in a sufficiently silent and open area (ambient noise and wind noise at least 10 dB below the noise being measured).
That area may take the form, for instance, of an open space of 50-metre radius having a central part of at least 20-metre radius which is practically level, surfaced with concrete, asphalt or similar material, and not covered with powdery snow, tall grass, loose soil or ashes.
The surface of the test track shall be such as not to cause excessive tyre noise. This condition applies only to measurement of the noise made by vehicles in motion.
Measurement shall be carried out in fine weather with little wind. No person other than the observer taking the readings from the apparatus may remain near the vehicle or the microphone, as the presence of spectators near either the vehicle or the microphone may considerably affect the readings from the apparatus. Marked fluctuations of the pointer which appear to be unrelated to the characteristics of the general sound level shall be ignored in taking readings.

I.4. Method of measurement
I.4.1. Measurement of noise of vehicles in motion (for type approval)
At least two measurements shall be made on each side of the vehicle. Preliminary measurements may be made for adjustment purposes but shall be disregarded.
The microphone shall be situated 1.2 metres above ground level at a distance of 7.5 metres from the path of the vehicle's centre line, CC, measured along the perpendicular PP" to that line.
Two lines AA" and BB", parallel to line PP" and situated respectively 10 metres forward and 10 metres rearward of that line, shall be marked out on the test track. Vehicles shall approach line AA" at a steady speed, as specified below. The throttle shall then be fully-opened as rapidly as practicable and held in the fully-opened position until the rear of the vehicle crosses line BB" ; the throttle shall then be closed again as rapidly as possible.
The maximum sound level recorded shall constitute the result of the measurement.
...

I.4.1.2. Vehicles with a manually operated gearbox
...
I.4.1.2.2.- The third gear in the gearbox must be engaged if the box has more than four gears;
...
The vehicle shall approach line AA" at a steady speed corresponding to the lowest of the following three speeds: - an engine speed equal to three-quarters of the engine speed at which the engine develops its maximum power;
- an engine speed equal to three-quarters of the maximum engine speed permitted by the governor;
- 50 kilometres per hour.
...

I.4.1.4. Interpretation of results
I.4.1.4.1. To take account of inaccuracies in the measuring instruments, the result obtained from each measurement shall be determined by deducting 1 dB from the meter reading.
...
I.4.1.4.3. The highest sound level measured shall constitute the test result. Should that result exceed by 1 dB the maximum permissible sound level for the category of vehicle tested, two further measurements shall be made. Three of the four measurements thus obtained must fall within the prescribed limits.

I.4.2. Measurement of noise of stationary vehicles
I.4.2.1. Position of sound-level meter
Measurements shall be made at point X (shown in Figure 2) at a distance of 7 metres from the nearest surface of the vehicle.
The microphone shall be situated 1.2 metres above ground level.
I.4.2.2. Number of measurements
At least two measurements shall be made.
I.4.2.3. Vehicle test conditions
The engine of a vehicle without a speed governor shall be run at three-quarters of the rpm speed at which, according to the vehicle manufacturer, it develops its maximum power. The rpm speed of the engine shall be measured by means of an independent instrument, e.g. a roller bed and a tachometer. If the engine is fitted with a governor preventing the engine from exceeding the speed at which it develops its maximum power, it shall be run at the maximum speed permitted by the governor.
Before taking any measurements, the engine shall be brought to its normal running temperature.
I.4.2.4. Interpretation of results
All sound-level readings recorded shall be given in the report.
The method used to calculate the engine power shall also be shown, where possible. The state of loading of the vehicle must also be given.
The measurements shall be considered valid if the difference between two consecutive measurements on the same side of the vehicle does not exceed 2 dB.
The maximum figure recorded shall constitute the result of the measurement.

I wasn't questioning the absolute numbers just the huge difference. Because of the distance and possibly other testing factors, it seems like the NISMO exhaust should have been quieter by the same relative amount.

I have heard that some people with nismo exhaust say that it is just too quite alone. Thats why they add cats.

Also, I may wait for the ingen 1985c exhaust

FYI

https://my350z.com/forum/showthread....threadid=48451

well i guess if you want quite exhaust. might wanna try Hi-tech Exhaust.

Because i have compared with my Friend's Nismo Exhaust in Australia here. The nismo Sound very loud and my Hi-tech is pretty quiet, But i mean is not as loud as Nismo.

Fujitsubo Legalis R is under 95 decibels. My Power Enterprise system was very quiet as well.

The Greddy Evo2 is under the legal limit of 95bd, but I havent measure it personally or see the actually sound level posted anywhere.

I wonder what the R*SR is without the silencers?