How loud is your aftermarket exhaust? A call for decibels
 

Hey everyone,

In my recent quest to find a more aggressive sounding exhaust, I tried a muffler delete. While it sounds MEAN, it's very loud. Having watched endless different aftermarket CBE videos on this site, I can safely say that watching a video alone doesn't really do justice for evaluating how loud a setup truly is. So, for myself and anyone else considering an aftermarket CBE I make a plea.

Let's make a list of different exhaust combinations and how loud they are both in and out of the car. Please use a SOUND METER to record the decibels produced (say, both in and out of car at idle and under hard acceleration...feel free to list more situations if you like). If you can add details that can make or break someone's decision to purchase a particular exhaust, please include them. Helpful info would include things such as drone severity and where in the RPM band you notice it, particularly good sounding areas in the RPM range, if you've had any complications with your setup (eg melted fuel lines or something like that). Feel free to add other pertinent info as well.

If your sound meter gives options, please use the following choices for accurate measurements:
A-Weighted
Slow Response

I'm particularly interested in FI and Berk setups, but do post anything you have for the benefit of the community.

I'll kick it off.

Stock Muffler Delete, replaced with custom bent aluminum tubes to tips.
~75-80db idle in car while warm
~80-85db in car while in 6th gear on highway (around 70-80mph)
~96db out of car under heavy acceleration
~104db inside car under heavy acceleration in 4k-5k rpm range (drone zone)
Pros: Very loud, unbelievably aggressive sound. Great off-throttle 'burble', screams during acceleration, sounds like an F1 car above 5k RPM, you will turn heads as people will mistake it for something very exotic. Saves some weight (~25lbs)
Cons: relatively crude sound with many different harmonics (raw sounding), drone under load: mild at <2k RPM and pretty severe between 3800-5k RPM. Probably little hp/torque gain.

Great thread idea. I was just going through all the exhaust vids trying to figure out which one to buy, and it's pretty difficult to figure out relative volumes.

Unfortunately, I don't have any data to supply. I settled on the Stillen because I think the FI might be annoyingly loud (and low) for me, but it hasn't arrived yet.

Anyone else with a DB meter? I know one of the promo vids included the DB meter in the video...

I'll see if I can get some sound levels once I get my car back today or tomorrow.

I'm expecting it to be pretty loud.

soooo...a butt dyno sound meter wont work eh?


j/k

i'll go to radio shack this weekend and get one...

Edit: scratch that they are 50 bucks :eek:

I'll have to see if I can borrow one from someone...

I'm OK with sending mine around to people who want to participate. Ideally we can find people in one area that can all use it together. Of course, I'd like it back :).

spearfish, PM me. i'll help you out with the F.I. setup (HFCs + 18" resonators)

For guys who want to have one in the toolbox this is new on the market...$20.
I've been meaning to order one...

Parts-Express.com:Mini Digital Sound Level Meter | sound meter sound level meter sound noise noise level noise level meter meters meter car SPL

http://www.parts-express.com/images/.../390-722_L.jpg

:eek: out of stock till next month

might want to include distance from the exhaust tip for out of car measurements...

Ah well...In stock here but $10 more...(still a deal)

sound level - MCM Electronics Search

found this one on the bay...

Boom Stick SPL1000 Digital SPL Stereo Sound Level Meter - eBay (item 260476243631 end time Sep-19-09 20:50:01 PDT)
http://i14.ebayimg.com/01/i/000/9e/7e/9145_1.JPG

Seeing the prices you guys are finding, it doesn't make much sense for me to send mine around by UPS. I do hope some people pick them up though. Think of all the possibilities: exhaust loudness, calibrate surround sound, ultimate farting contest...

:koolaidwall:

Ultimate Beer Belching Contest!!!

Hey spearfish,

I don't have a decibel meter, but I did just get Berk HFC's installed. I'm in the Chicago burbs and would not mind driving by down town if you want to get a reading on the loudness of those.


I'm in, any kind of beer in particular? :icon17:

nope, just your usual

Cool, I'm down with that. You have the Berk HFCs and otherwise stock exhaust?

I sent you a PM.

Might want to come up with a standard of measurement...

IE, 3ft back, mic facing driver's side exhaust tip, centered.

Then maybe another sample from 10ft back, centered on the same plane between the tips.

I live out in the middle of a social desert (compared to most of you east/west coasters), but there are those flat rate USPS boxes that aren't too bad for shipping anywhere...

We could ship around mine (it's sitting in a closet doing nothing) and get readings from everyone off the same meter.

A little calibration (no pun intended)
 

These are either dB"A" or dB"C" meters. The difference in A or C weighting is that the noise is measured and adjusted on a third octave band basis by either an A-weighted curve or C-weighted curve, essentially different values for each third octave band frequency. After the A or C adjustment a log sum of the frequency range (specified on each meter specs) is performed. The number that is shown on the display will be the log sum value.

If someone has a dBA meter and another person has a dBC meter the answers will be different from the same noise source, in addition some meters have different frequency ranges the adjustments are performed on so another different answer.....

The dBA or dBC weighting were established as a means to measure noise environments as the ear hears them and to determine hearing damage due to exposure.

Too much blah blah blah acoustics but if people start comparing numbers knowing the background information A or C weighted and frequency range determined over would be helpful.

What's really cool (at least for an acoustics guy) but expensive, would be a third octave band analyzer.

Real Time Analyzer and Sound Level Meter with 1/3 Octave Band Filters

I updated the original post to request A weighted values. Some meters like mine from radioshack give the option of either weighting. My understanding is that c is best for music and includes a wider frequency range that is beyond our audible range. A weighting stops at a low frequency of 500hz, and a site I saw suggested it's best for car sound readings. As an aside, my values are listed as A weighted. When I used c weighted, everything was about 10db louder.

Exhaust sounds will have quite a bit of energy below 500Hz.

For perspective...the base beat that goes through you from someone's seriously amped car audio is typically 20Hz-40Hz

Got the PM, thanks.

Yep, I have the Berk HFC's with a stock exhaust. I'm actually surprised at how much louder this already is compared to the stock cats. I'm now trying to decide whether I want to stick with this or go for an aftermarket exhaust as well. The sound now is ok, but a bit harsh, wouldn't mind a somewhat "deeper" sound.

reported TyiweonRaq as a dumba_ _

Of all the threads to choose too. Maybe he missed the Fast Intentions thread with nearly 3,000 posts?

Thanks for reporting. Took care of him. :tiphat:

:tup: most excellent otf! glad to see you got AK's back :tiphat:

I heard someone on here got a noise ticket in Ca. they were running Stillen CBE & Berk HFC's. I'm curious to see how loud that combo is. I noticed that the test is suppose to be run at a constant RPM (see below) I wonder if this guy was accelerating when he got the ticket. Anyway, Here are the rules for California. Don't know how old this is.

CCR 1036 Passenger Cars and Light Trucks and Buses

Exhaust systems for motor vehicles, other than motorcycles, gross vehicle weight rating of less than 6,000 LB (2,722 kg) shall comply with the specified noise limits when tested in accordance with the following specifications:

(a) Measuring Site. The vehicle under test shall be positioned either on outdoor pavement or on a shop floor ( but not over a hoist or pit) in a location where the exhaust outlets are near an open shop door. No sound-reflecting surface other than the pavement and the vehicle being measured shall be within 10 ft (3.0m) of any part of the vehicle.

The testing is done in an environment in which there is minimal sound contamination. Please note that there is nothing stating highways or other public roads as being an exception to this criterion.

(b) Microphone Location. The microphone for the sound level meter shall be at the same height as the center of the exhaust outlet. The microphone shall be no closer to the pavement than 8 in. (203mm) when the exhaust outlet is lower than this height. The microphone shall be positioned with its longitudinal axis parallel to the ground, 20 inches plus or minus 1 inch (508mm plus or minus 24mm) from the nearest edge of the exhaust outlet, and 45 degrees plus or minus 10 degrees from the axis of the outlet. For exhaust outlets located under the vehicle body, the microphone shall be located at the specified angle and at least 8 in., (203mm) from the nearest part of the vehicle. For exhaust outlets that make an angle of 45 degree or less with the longitudinal axis of the vehicle, the microphone shall be outboard of the exhaust axis. For exhaust outlet angles of more than 45 degrees, the microphone shall be on the side of the exhaust axis to the rear of the vehicle.

This denotes where the sound measuring device is relatively close to the exhaust outlet. Notice that it does not make any references to provisions for sound level testing done from distances greater than 21 inches. <

(c) Engine Operation. The engine shall be at a normal running temperature with the transmission in neutral. System sound level measurements conducted for certification by exhaust manufacturers shall be made at an average steady-state engine speed of three-quarters of maximum rpm. Sound level measurements conducted by licensed muffler certification stations shall be made at an average steady-state engine speed of 3,000 rpm for vehicles manufactured before 1972 for which the station does not have a maximum rpm data.

Please notice that the engine is supposed to be running and the law has no provisions for parked vehicles. Note that the certification can be done by the manufacturer of the exhaust system. There is no requirement that the manufacturer sound test each individual vehicle. Re: "licensed muffler certification stations," the letter from the California Highway Patrol file Number 60.A9190.A9181.062.9610186 states in the third paragraph that these facilities were canceled in 1978 due to budgetary cut-backs.

(d) Exhaust Sound Level Measurement. The recorded exhaust system sound level of a stationary vehicle shall be the highest reading obtained during the test, disregarding unrelated peaks due to extraneous ambient noise. When there is more than one exhaust outlet, the reported sound level shall be for the loudest outlet. When there are two or more exhaust outlets separated by less than 12 in. (305mm), measurements shall be made on the outlet closest to the side or rear of the vehicle. (Figure 4). The sound level for the motor vehicles with the manufacturers' gross vehicle ratings of less than 6,000 LB (2,722 kg) except motorcycles, shall not exceed the following limit:

The statement stating extraneous ambient noise refers to noise coming from places other than the exhaust. For this reason, testing cannot be done in a sound-contaminated environment. It would be logical that a roadside or a highway would be a sound-contaminated environment.

(1) Sound Level Limit. The exhaust noise shall not exceed 95 dB(A).

is that 95db at idle rpm?

On the 370Z it would be about a steady state 5600 rpm. I don't think our stock exhaust would pass that.

Yeah, should pass no problem, it's only under load or revving that this engine get loud, steady rpm should be fine.

Look at OP, his DB rating is without mufflers. (although not following mic placement guidelines) gives us some kind of idea.

Stock Muffler Delete, replaced with custom bent aluminum tubes to tips.
~75-80db idle in car while warm
~80-85db in car while in 6th gear on highway (around 70-80mph)
~96db out of car under heavy acceleration
~104db inside car under heavy acceleration in 4k-5k rpm range (drone zone)

Umm, yeah. Despite my readings being from a muffler delete, I think we would fail miserably. The microphone has to be 20 INCHES from the exhaust outlet. That 96dB was from about 300 feet away (watch the video again). It's probably 130dB at the tips (all I know is I did't want my ears anywhere near that close when I had the muffler off). Even with just the Stillen CBE now, I think I'd still fail to meet those guidelines.

Hell, I bet engine noise alone (forget the exhaust) would be over 95dB at 20 inches from the tips.

dB
 

Great thread! Look forward to some results.............................

Stock cats with Stillen CBE to be added shortly...

any updates?

Stillen CBE with ERZ High Flow Cats. 89dB at WOT inside the car

Hopefully we can get at least one/some NISMO owner(s) to jump in on this test. I am curious as to how loud the stock setup is and how it compairs to the "legal" limits. I won't be picking mine up until late March at the earliest, but I will try to get a reading at that time.

I will get number for the Invidia Gemini CBE tomorrow. Next Saturday I get my ERZ HFC's on so I will post those numbers too.

Yes, please post the numbers and your thoughts on the Invidia BEFORE the HFCs are added. Thanks! :tup:

wow 3 pages and 1 post of an exhaust measured. whats so hard about getting the device, sticking it 20 inches from your exhaust and testing it? great thread idea wasted by lazy people. really? worried about the cost of it? 50 too high? YOU OWN A 370 Z FOR CHRISTS SAKE, so you can obviously afford a 50 dollar device. I would do mine, but you can look at ARKs site...... already done.

Why no dl a dbtest from your phone app store for free. Sure they are not the best and every phone brand/model will record a little measure a different db. Why not also inclue your phone brand, model and which db app u used? The idea of free anything will hopefully get more people to participate = better survey.

So make a standard as far as recording distance, facing x way, rev to x rpm, in front of left exhaust, in open lot, in garage or whatever.