todinlaw

We are in the process of signing a contract with a track and for the first time we are being confronted with a noise limit in the contract. I know you west coast guys have to deal with it all the the time. Is this a difficult limit. I have a 997gt3 and I am just about to install Alex, sharkwerks bypass, am i going to have a problem?

Will the day come we will all be driving electric cars?

aeshultz

Frank;
SCCA deals with this all the time - they even have a a staff position of "Sound Control." I'm sure the Lime Rock guys can comment - they run a fairly strict limit.
BTW - I have a meter if you'd like to test.

chrisp

Not sure any of us have experience with a 50' limit. That's much different than an on-track reading...unless what they have in mind is an on-track reading.

If you can, have them stipulate how the test will be done and in what environment. Still or rolling? RPM specification? Environmental conditions and nearby physical structures heavily influence sound readings. Just make sure they are consistent and measure it in the same place under the same conditions every time. There's a standard used for ATV testing. That's the best thing to use if you need something to mimic.

That being said, if we were allowed 103db at Lime Rock a lot of guys could run nearly open pipes. 103 is pretty loud...but again that's not at 50'...it's more like 75-100' in some places.

MUSSBERGER

Yea those are pretty vague stipulations. And is the meter accurate?

dmoffitt

That seems plenty loud, Calabogie was 100db from 30ft (in the paddock / tech line, rev'd to 3/4 of redline). Tremblant, 92db at 50ft measured on the front straight... but, I could be misunderstanding ...

M758

Well 103 at 50' ft is pretty much the standard SCCA limit and pretty loud on dB scale. Official most SCCA regions if not all use that limit. I bet alot don't both enforcing and that is track dependant.


Laguna Seca has some of the quietest limits of any track at 92 dB on most days. That is ALOT quieter than 103 as it is on a log scale.

Many tracks test for sound at some point on the track. They will put a sound meter 50ft off track and along a straight. The black flag any car that goes by over the limit. At Laguna the meter is always on one side of car in one section of track. So many cars point the exhaust in the other direction and some even lift when driving by to lower the reading at the meter.

stownsen914

Agreed that 103 db at 50 feet is on the loud side. At Lime Rock we have to make 90 db at 50 ft, measured on the front straight. For comparison, I believe that older 911s running open exhaust used to be on the verge of the old SCCA sound limit of 108 db. I think open Supertrapps (just the cannister, no disks) is 100 or a little more on a 911. If you have any muffler at all, you'll probably make 103 db.

Scott

85Gold

103db is loud. At Roebling Road on the front straight a Spec Miata runs around 97db and my T3 S2000 straight pipe from cat back runs 95 to 97db. I do not think a 996 GT3 with bypass pipes would pass. Factory Five's were backing off by the sound meter to pass at a track day.

Peter

earlyapex

A friend driving a 996 with bypass pipes popped 105 db at Thunderhill on a warm, clear day. The meter is in a booth on the right hand side of the front straight, after the last turn. The track is owned by the SFR of the SCCA. His day was done.

Intake noise will also be measured. Mooty had to stuff material over the intake of his GT3RS in order to make sound at Laguna Seca.

RSchoeni

I'm headed to RR next week. Where do they put the sound meter?
_____
bs

Jarez Mifkin

My 993 RSR passed Barber's 104 limit with supertrapps with 12 discs on each side.

997gt3north

[QUOTE=todinlaw;5624626]We are in the process of signing a contract with a track and for the first time we are being confronted with a noise limit in the contract. I know you west coast guys have to deal with it all the the time. Is this a difficult limit. I have a 997gt3 and I am just about to install Alex, sharkwerks bypass, am i going to have a problem? QUOTE]

Yes and no - depends on a few things.
I have a 997gt3 with the sharkwerks exhaust and have done db tests
If you search on some of my old posts i posted db levels - before and after.
It is definitely going to depend on rpm range.
You will not pass if you do a 8200rpm flybye at 50ft - otherwise you will be fine.

todinlaw

Thanks guys, even before I have the $@%& thing installed, I am getting a headache. I will see if I can find Paul's old post and see if it helps I will also get more info from the track to see how this will work.

todinlaw

Alan If you going to Mid-Ohio in august bring it, well do a test.

85Gold

It is app. 1/2 way between the start finish line and turn 1. Right where you are screaming along.

Are you doing Seat Time.???

Peter