How Loud is Your Cobra ?
 

I'm getting a 85 DB reading of at 7 feet away from the car at a 45 degree angle . 427 Ford 11.3 to 1 compression ,solid cam, Idle 1100 RPM .
It seems loud or am I wrong?
Thanks

I was just talking about this with my wife the other day.
My car is actually louder than I,d like it to be. I would rather have a
softer throatier exhaust note .

What kind of car/engine do you have? Guessing that 85 DB is normal for these cars.

The pipes on my Superformance have gotten progressively louder over time. The only thing you can do is look at your options regarding quieter replacement pipes.

The Spiral Turbo Baffle prototypes were done on my car...So these tests were taken before hand. At idle, from a distance of 20'..I pegged the meter at 104 DB.

I think mine is 85 dB when the engine is shut off!!! Really, I dont know how I would ever get down to 85 dB...

Sidepipe: 103 dB, 20', 90 degrees to side, 1000RPM. 108dB, 20', 3000Rpm.
Open header: 105 dB, 1000RPM. 115 dB, 3000RPM.
Sideoiler, 10.3, solid cam.

I was told that I was in the 105 dB range at 20' while autocrossing.

What? :LOL:

What is loud????
 

Weakest sound heard 0dB
Whisper Quiet Library at 6' 30dB
Normal conversation at 3' 60-65dB
Telephone dial tone 80dB
City Traffic (inside car) 85dB
Train whistle at 500', Truck Traffic 90dB
Jackhammer at 50' 95dB
Subway train at 200' 95dB
Level at which sustained exposure may result in hearing loss 90 - 95dB
Hand Drill 98dB
Power mower at 3' 107dB
Snowmobile, Motorcycle 100dB
Power saw at 3' 110dB
Sandblasting, Loud Rock Concert 115dB
Pain begins 125dB
Pneumatic riveter at 4' 125dB
Even short term exposure can cause permanent damage - Loudest recommended exposure WITH hearing protection 140dB
Jet engine at 100' 140dB
12 Gauge Shotgun Blast 165dB
Death of hearing tissue 180dB
Loudest sound possible 194dB

OSHA Daily Permissible Noise Level Exposure
Hours per day Sound level
8 90dB
6 92dB
4 95dB
3 97dB
2 100dB
1.5 102dB
1 105dB
.5 110dB
.25 or less 115dB




NIOSH Daily Permissible Noise Level Exposure
Hours per day Sound level
8 85dBA
6 86dBA
4 88dBA
3 89dBA
2 90dBA
1.5 92dBA
1 94dBA
.5 97dBA
.25 or less 100dBA
0 112dBA

Perceptions of Increases in Decibel Level
Imperceptible Change 1dB
Barely Perceptible Change 3dB
Clearly Noticeable Change 5dB
About Twice as Loud 10dB
About Four Times as Loud 20dB


Sound Levels of Music
Normal piano practice 60 -70dB
Fortissimo Singer, 3' 70dB
Chamber music, small auditorium 75 - 85dB
Piano Fortissimo 84 - 103dB
Violin 82 - 92dB
Cello 85 -111dB
Oboe 95-112dB
Flute 92 -103dB
Piccolo 90 -106dB
Clarinet 85 - 114dB
French horn 90 - 106dB
Trombone 85 - 114dB
Tympani & bass drum 106dB
Walkman on 5/10 94dB
Symphonic music peak 120 - 137dB
Amplifier, rock, 4-6' 120dB
Rock music peak 150dB


NOTES:

One-third of the total power of a 75-piece orchestra comes from the bass drum.
High frequency sounds of 2-4,000 Hz are the most damaging. The uppermost octave of the piccolo is 2,048-4,096 Hz.
Aging causes gradual hearing loss, mostly in the high frequencies.
Speech reception is not seriously impaired until there is about 30 dB loss; by that time severe damage may have occurred.
Hypertension and various psychological difficulties can be related to noise exposure.
The incidence of hearing loss in classical musicians has been estimated at 4-43%, in rock musicians 13-30%.
Recent NIOSH studies of sound levels from weapons fires have shown that they may range from a low of 144 dB SPL for small caliber weapons such as a 0.22 caliber rifle to as high as a 172 dB SPL for a 0.357 caliber revolver. Double ear protection is recommended for shooters, combining soft, insertable ear plugs and external ear muffs.
Statistics for the Decibel (Loudness) Comparison Chart were taken from a study by Marshall Chasin , M.Sc., Aud(C), FAAA, Centre for Human Performance & Health, Ontario, Canada. There were some conflicting readings and, in many cases, authors did not specify at what distance the readings were taken or what the musician was actually playing. In general, when there were several readings, the higher one was chosen.

Your stuff is scary loud!:eek: I heard you at WOT in Rehoboth.

David

I have 3" collectors into 3" Flowmasters with out the rear exhausts. Loud but the noise is behind you and no burnt legs!

How accurate is the iPhone app (decibel meter)?

I just had my car measured at 105 db with a throttle blip to 4000 rpm, from about 10 feet. It's the first time I've ever had mine metered, and have nothing to compare it with.

The Superformance mufflers are 2 inches dia inside. I replaced mine with 3 inch so as not to choke the crap out of my Roush 427. The stock superformance and other mufflers of the 2 inch size are really for a small block (or) around but not exceeding 400HP

If you want it quieter you have to go with smaller dia mufflers.

If you have a 427 you need a minimum of 3 inch dia mufflers 3.5 would be better (no bigger). With 500+ HP 3 inch work well but are loud. Superformance come with 2 inch int. dia. mufflers and they suck about 100 HP out of the motor at 6000 RPM.

Smaller is quieter....period. No packing or other BS internals are going to substantially make your car quieter. if you're will to give up some more HP go smaller!

"Weakest sound heard 0dB"
With that as the opener, no need to read the rest lol

I took an industry standard reading at .5m or about 20” away from the tip of the exhaust on the same plane at a 45 degree angle, (A) setting on asphalt. I have louvered mufflers installed backwards.

idle 95dB
3000rpm 110dB
At 10ft away idle same plane and angle 85dB
At 20ft away idle same plane and idle 80dB

How do you like the mod. I will be sending my SPF side pipes out to mod them to a 3" dia this month, and really like the sound of the ones I've heard that have had this done.

Loud enough that I put an earplug in the L ear if I am driving more than 10-15 min... but not loud enough to want to quiet it down!

Forget the quieter idea. If I have to give up 100hp then I'm staying with what I have

A cop heard me 3 blocks away when I spun it to 5000 rpms. Got pictures to prove it but no ticket. A buddy of mine would wait in his driveway till I got onto the hiway and opened it up a little. He is one and half miles away and could hear me.

Now I've changed the 2 1/2" x 24" mufflers for 3" x 28" and I'm a lot quieter.
I believe if you add a longer muffler your exhaust noise will be less.

Dwight