CentralCoaster

I have a stock TPI with stock headers, a single 3" high flow cat and no mufflers.

How loud is 93 dB? If an event has noise regulation, is it wise to just chance it the first time out and risk getting the boot?

I have no idea how loud my exhaust is in dB, or what rpm & distance it's measured at, or even how to go about measuring it.

93dB is a pretty standard limit right?

95jersey

I think Lime Rock is the worst at 89 or 87db? Not sure. To give you perspective. I have an 01Z with Kooks race headers, into 3" collectors, dumping into an X pipe with NO CATS, then into a Stinger cat back, which has strait pass through mufflers. It's pretty darn loud and I pass Lime Rock. The cats really keep the noise down considerably. Take them and the mufflers off and your definately close. I am sure the Stingers muffle the sound a bit, but not much. I hope this helps.

StArrow68

The solution to being too loud seems to be L angle pipes. Seen this several times at Laguna Seca and even Sears Point. Laguna can be as low as 90Db and Sears point is in the mid 90's, depending on day. At Laguna the sound is measured off the right side of turn 5 so people attach L angle's with exhaust pointed left, Driver's side. More trouble on a Vette with 4 pipes but seems to do the trick on pretty loud cars.
Randy

John Shiels

LRP is actually 85 but they let you run at 87. Depends on weather and how they measure it. Went for 2 years same setup third year NFG and got the boot. Then put a soda can over one side which didn't take much performance at all with an X pipe.

CentralCoaster

So I'm thinking I should bring some small citrus just in case.

dmwhite

if you're worried about passing the noise restrictions, get a turndown (or turndowns) and bring them to the track...most tracks (check with the specific tracks for their sound levels and policy) will give you 2 chances to get below the limit (after they determine you are over it)before they kick you out...if you are over the limit, throw on the turndown(s) and aim them away from the where they are measuring or aim them straight down...

i was worried about being too loud for roebling road (103 dB at 50ft i think) so i got a turndown but ended up not having to use it (they measured my car at 101 dB )

davidfarmer

yes, turn-downs are great. You may need to turn them to one side, up, down, whatever, to get the sound away from the meter.

You can get a decibel spl meter at radio shack. Get a friend to stand by the road while you drive by a WOT. However, trackside reflections (concrete walls, etc) can amplify matters.

ryan0

FLP headers, WITH cats and borla stingers.. 99.1 at laguna.

HalM

You would need mufflers to make 93 dB at Laguna Seca...A lot of club events are 90dB now...

Gordy M

Where they measure the sound is the most important information you need. Some tracks will give you 100 db but it is measured at trackside and the highest is Waterford Hills in Michigan with 75 db but it is measured at the wall next to the subdivision. By the way, the only engines that break the db limit any more at WH are the local lawnmowers.

A corvette with headers and corsa off road TI exhaust can make the db limit with super traps.

robvuk

A db reading or specification is meaningless without a distance. (e.g. 90db@50ft.) Double the distance and db drops 6 db or the reverse. It's up to you to ask what their individual spec is. If you know in advance what the db is at what distance, you can measure and calculate your own. As Farmer stated, if you are measuring from the outside of a turn that has a concrete wall on the inside, it can add as much as 3 db.

robvuk

93 to 96db is about the same as a rock concert at the back of the venue. Pretty loud! The limits at the track may be mandated by how close or far they are from a neighborhood, so it could be anywhere, and then it could change depending on what day or what time of day. The only standards are the noise ordinances that are set by your local police departments. The only reason they don't give more tickets for noisy cars and motorcycles is that they don't have the equipment or expertise to measure the violators accurately.

CentralCoaster

So what sort of electronic ears do I need to measure it? and who would have one?

95jersey

Just an FYI...no matter what kind you use and how you measure, it will be different at the track. I had a buddy measure me from about 15ft away at full song on a back road and reach over 91db. I went to an 85db track and had no issues?!?!

So this basically told me that it was almost worthless to measure.

rasrboy

Roebling Road in Savanna, GA is 103 db. I had to put mufflers in (112) and turn downs facing the ground and it muffled it enough to get by at 104 and he let me go.

robvuk

I guess you didn't read my post above.

If you measured 91db at 15ft., it would only be 85db at 30ft and 79db at 60ft. etc. etc. The only thing that will make it different is the inaccuracy and discrepency between different models of non-professional equipment. A small variation due to the surrounding acoustics from trees, shrubs and concrete walls.

You can get cheap handheld analyzers at Radio Shack. They won't be great but they'll give you a reference.

MistressMotorsports

On my race C4 (headers, X pipe, no mufflers) , I had to run mufflers to get my car to pass, just turn downs didn't do it at Laguna. I wound up running Supertrapps so I could tailor them to be just legal and give minimum restriction. Since you hvae a "sort-of" muffler in the cat, you might be ok, but bring alternatives as recommended. The Supertrapps cost me a bunch of hp, so it was a passable but not optimal situation. On my C4 street car (heads/cam, stock manifolds, no cats, Flowmasters) I always passed at Laguna without turndowns, although it might have been 93 db for club events back when I had that car.

Mike

Gary K

It sucks, but if you know where their meter is you can just let off the throttle when going by it. Better than getting the boot if you're already at the track and can't make the needed mods though.

joemoia

Kevin,

I don't know where you plan to run, but as a reference a stock C5 Z06 w/stock exhaust at WOT will break the 92db limit at Laguna Seca. At Laguna the noise booth is located going up the hill from T5 to T6. To get around the noise police you have to short shift going up the hill to stay within the limit.

Joe M

Dirty Howie

Driving behind you last saturday I can say your car is NOT loud....more like a little pop gun

Of course I'm used to driving behind behind JB's supercharged blast gun exhaust


DH