What is a good DB sound level?

[dlampe]

How loud is the typical cobra pipe? What about open pipes? Is 5 db's a noticeable difference?

[greg schroeder]

Every 3 db is double the volume or if 3 db less then half the volume.

[Clois Harlan]

I like about 15 db's

[Hotfingrs]

Far spread is still the
theory of psycho-acoustic pioneer Stanley Smith Stevens, indicating that the doubling or halving the
sensation of loudness corresponds to a level difference of 10 dB

That being said, my car at 30 feet at idle, was measured at 104 DB

[Roscoe]

What???????????????????????????

[greg schroeder]

http://www.sengpielaudio.com/calculator-levelchange.htm

I guess I was wrong. I was thinking in speakers and electronics. Twice the watts will make your speakers 3 db louder. It looks like if +/- 3 db it is double or half the energy.

http://ntrack.com/wiki/index.php/How_LOUD_will_it_be%3F

[Bobcat]

I believe db levels are measured on a logarithmic scale ... which means things aren`t linear . Therefore as , as Greg , said , a small db change means a fairly significant in sound level .

[CBattaglia]

Originally Posted by Roscoe

What???????????????????????????

Huh? You will have to say it in my right ear please.

[rustyBob]

when i was drag raceing they measured the db level at 50 feet.....
if you where over 96db at the start line at wide open throttle....
no raceing for you.....to loud and you went on the trailer....

[Skuzzy]

Yep, for example, going from 96db to 104dB makes that 104dB pressure level 12 times higher/louder than the 96dB pressure level.

[jhv48]

I just kept raising the decibel level till my wife stopped trying to talk over them.

Just right now!

[951mat]

You're getting old Dean. You don't want to choke your engine do you?

[jdean]

I cut off the standard mufflers and put on the Classic Chambered. Less restriction and less noise.....until you really hit it.

[Silverback51]

When your ears bleed, go back to the prior setup.

[Hotfingrs]

You couldn't talk to the passenger easily while cruising.

That means you weren't going fast enough, the sound was still beside you, GO FASTER, put the sound behind you.

[jdean]

Dean, it will basically be the same as the Howe muffler I would guess. Very loud. I had them on my CR and folks would put their hands over their ears when I passed them.

Best example is John Ross. You can hear him coming for miles...and you can hear him leaving for days!

[Excaliber]

I recently took a sound meter to measure DB's at a local auto cross here. Many tracks DO have a DB limit, which seems to vary with the day of the week, time of the day and the particular event. Some tracks are more strict than others. The DB requirement seems to vary from 99 to 103 or so. I would ASSUME they all take the measurements at about 50 feet? Typically at a turn on the track somewhere. So, if you know what turn and where the sound meter is you could adjust throttle opening or turn your side pipe exit port to face away. Some car's do have an adjustable exit tip on the sidepipe specifically for this purpose. I may modify my side pipes in such a way.

Where was I? Oh yeah, so I took some DB readings at the START line as well as a straight section "at speed". The start line was consistently higher DB. Plenty cars exceeding 103 DB on the start, 105, 106. Surprisingly "at speed" showed a significant drop in DB, 5 to 10 points.

My ERA idles at 106 as read from the cockpit with me sitting in the drivers seat. I ALWAYS wear ear plugs, everytime, even for a short trip. I already wear two hearing aids, I'm just trying to save what I got left.

Because this is becoming more and more of an issue (in particular California) there are some ongoing studies as to what works and what doesn't. Glass packs don't work, period (that would essentially be side pipes). Borla and many other after market exahust systems don't work. The list of systems that don't work is long, the list of systems that do work is short. On the short list is Spiral Turbo inserts.

When I was talking to the Spiral Turbo folks and told them I had an FE, I could hear them groan. Apparently the FE engines are among the toughest to get the DB down on.

http://www.spiralturbobaffles.com/index.html

[Hotfingrs]

I think it was 2003 when STB did their prototype for the Cobra on my car. They were the ones that measured my db at 104 at idle. After install of their product my db went down to 97 or 98, so they will quiet your car. On a side note, I lost a second and a half and 16 mph in the quarter. Needless to say, they are sitting on my shelf.

[Excaliber]

Prototype may be the key word there Jack.

Toms Motorsports have been running their small block FFR with spirals (no choice as per required DB levels at some tracks) and have met with some pretty good results in reducing DB without loosing much HP.

I loose close to a 100 horse with my STOCK side pipes all ready. Of course the bigger the engine, the more flow of cfm, in and out, the more significant the loss will be. A big inch engine is going to be hard to handle no matter what you do. I'm pretty sure I would lose less and be quiter with spirals.

[Hotfingrs]

You're probably right Ernie, everything is going to be a trade off. Quieter, more hp loss, some performance loss. Open exhaust, quite loud, and zero performance loss. Now you just have to find a place in between that you can live with.... You've already found out that losing a couple hundred horses, didn't cost you that much in the quarter... and you have a street friendly engine now.