Laguna Seca 92db Limit...hmmm?

[Thinkkker]

I could not get within a mile Seca then. SCCA put out a 100db limit for Tours and Nationals. First day I have broke 100db once each time up.

Guess I need to get the cats put on.

 

[RolloTomassi]

Sorry to ressurect this post from the dead, but I am looking at going to Laguna Seca coming up but would hate to travel the 5-6hrs up there only to be turned away beacuse of noise!

06 GT w/ JBA shorty headers, o/r H pipe (welded in resonators) & corsa axlebacks.

It's loud... but is it too loud?

 

[irishpwr46]

id say anything without cats is going to have problems. im running stock manifolds, o/r h, roush mid-mount resonators, and borla stingers and my car is pretty damn loud

 

[kevinatfms]

thats why i invested in some stocker gt500 mufflers. got some tips off pipes(4" rolled tips) and got them welded on. looks like i have something nice and with long tubes still has a growl but i dont get looked at too much at tracks or on the street(po-po)

i would say grab some stockers just to be safe, as long as your not pushing too much power they really wont hinder your performance besides the weight penalty of stockers over smaller mufflers. maybe add some of the quiet flow cherry bomb style mufflers in the OTA pipes?

 

[RolloTomassi]

Got a db meter from amazon. Seems pretty accurate on most things. From 3ft away at 5000 rpms it registered 107-113db. Enough to wake the neighbors for sure.

I think I still have my old stock mufflers, it might be worth a try to slap those on and see if they bring it down significantly.

Not all that stoked about the idea of changing out the mid-pipe for a track day. Maybe I'll bundle it when I have to get the car smogged or something....

 

[Norm Peterson]

What is it at distances more in line with the distance off the racing line that the sound measuring equipment would be set up at?

Autocross sound measurements are typically taken at something like 50' - 75'.


Norm

 

[kevinatfms]

IIRC around here it is normally set at 50' at trackside facing toward the rear of the vehicle.

 

[SoundGuyDave]

A few factors to consider...

1) We don't know what weighting system they use on the trackside meter. "A" weighting and "C" weighting will give drastically different readings depending on the low-frequency content of the measured signal.

2) Inverse-square law applies. That is to say that there is a 6dB change per doubling or halving of distance. Assuming your measurement at 3' is correct, one would expect to see approximately a 24dB reduction at 50'. Well, 48', but still... Given that reduction, IN THEORY, you would be in the 83-89dB range.

3) When you took your reading, was that in an open area? Was the engine under load? Was it on-axis with the tailpipes or off to one side? All these can affect the reading, in comparison to the trackside meter.

 

[Grip]

Dude...I have a CATTED X, stock manifolds and SSS Andrenaline Mufflers...and I got booted twice. Don't bother with an o/r pipe.

It's worth noting, the first time I ran there, I had the same setup but with Mac's instead...and wasn't booted.

 

[Bodam]

My understanding, and I don't know this for fact, is that the land the track is on is municipal owned, meaning the whole deal is government-run... Event organizers, outside of the pro series that run there, apply for dates, which are then selected by lottery. The track also only allows "X" number of exemptions to the noise limit, which are soaked up by the pro series events, thus leaving the "marque" clubs with the noise limit intact. It wouldn't surprise me at all, being in the People's Republic of Kalifornia, if the noise limit wasn't an OSHA thing.

OSHA only applies to employees. They have no care for the public at all.

 

[SoundGuyDave]

Oh, I agree... However, the sound limit could be there to "protect" the corner workers, grid marshal, safety truck personnel, etc.

 

[Norm Peterson]

Having worked a number of autocrosses where there were some "ear-bleeders" running, that's a real possibility.

Never mind what happens to the sometimes important ability for event workers to communicate when voices can't be heard over the noise.


Norm

 

[irishpwr46]

im not a huge fan of what some people get away with. like a porsche 914 with a supertrap exhaust with no inserts coming screaming through my corner.

 

[RolloTomassi]

My understanding, and I don't know this for fact, is that the land the track is on is municipal owned, meaning the whole deal is government-run... Event organizers, outside of the pro series that run there, apply for dates, which are then selected by lottery. The track also only allows "X" number of exemptions to the noise limit, which are soaked up by the pro series events, thus leaving the "marque" clubs with the noise limit intact. It wouldn't surprise me at all, being in the People's Republic of Kalifornia, if the noise limit wasn't an OSHA thing.

How completely unfair! The rule applies to some but not to all? How does that make any sense? Why would Pro events be exempt and then enforce a limit on the rest of us? That's like saying yeah, you can play a pickup game at Staples center, but we're going to limit it to half-court.

I always wondered how they got by with the historic races. If you've heard some of those cars you'll know what I'm talking about.

Personally, I'd like to know why 92dB? Is that an arbitrary number or does it have some legal precedent?