Exhaust too loud for track?

[Alex Murphy]

I have already paid to go to Track Night in America at Lime Rock park in CT. The I found out that there is a sound rule. Your car has to be under 86db at 50 feet away. I have long tube headers, high flow cats and solo performance mach X catback. Do you think I will have a problem?

If so, any ideas on the best easy way to quiet it down enough?

[JOHNSONROD]

86 DB is quiet man. my guess is you will be over. there are lots of different weighted averages and ways to take sound readings. if its a true 86 DB at 50 ft, lots of stock exhaust would be over.
with LT headers, it will take tail pipe baffles and you might still be over. im not familiar with that exhaust. is it high flow mufflers or what?

[Alex Murphy]

Originally Posted by JOHNSONROD

86 DB is quiet man. my guess is you will be over. there are lots of different weighted averages and ways to take sound readings. if its a true 86 DB at 50 ft, lots of stock exhaust would be over.
with LT headers, it will take tail pipe baffles and you might still be over. im not familiar with that exhaust. is it high flow mufflers or what?

From Solo website:

" The muffler was designed and engineered differently than most other mufflers. It is an X style muffler.

The inner compartment (not the flow thru X but the side compartments) is split into four different chambers, each with ceramic fiber and stainless steel wool packing. It is a true “X” design and creates a low pressure system, while the four side chambers ensure that the packing won’t break apart and change the sound and efficiency over the years.

It is a dual 2.5″ in and 2.5″ out design."

I am sure my car is too loud now. I need to find a way to quiet it down for the track.

[CrazyRED]

I saw this post in the general forum and didn't want to get drawn into another argument thread there. Glad you posted here.

Is it 86db at idle? If it's at idle, I think you have a pretty good chance at passing. I guess there's a lot of variables, like will they measure in the front, back, or side? If it's the front and you have rear exit exhaust I would bet you've got it in the bag.

I work in the crane industry and do a lot of work for mines. MSHA requires you to wear ear protection at anything over 86db and that's a pretty decent amount of noise. Decibels increase exponentially, for example you might think 70db and 90db are fairly close in noise rating, however the difference in noise is 4 times greater.

I'm looking forward to your results, I've never heard of a noise rule at a track before. Do all vehicles have to abide by that rule, or just the class you're in?

[Alex Murphy]

From what I understand there is someone measuring 50 feet from the track and your car cant go over 86db. I am not sure if they measure at different points on the track or just one spot.

I think its a rule for this track no matter what class because there are houses close by and the people complained.

[CrazyRED]

Originally Posted by Alex Murphy

From what I understand there is someone measuring 50 feet from the track and your car cant go over 86db. I am not sure if they measure at different points on the track or just one spot.

I think its a rule for this track no matter what class because there are houses close by and the people complained.

So they are measuring while you are under throttle? There's a possibility you might still pass. A diesel truck under acceleration is around 86db. I would bet if you're close to the number they would pass you. I mean, think about this in terms of a business model. They are a race track, race cars make noise, a lot of noise. If they have enough business to keep the track up and running most cars must pass or they would go out of business because nobody could pass.

[Alex Murphy]

Originally Posted by CrazyRED

So they are measuring while you are under throttle? There's a possibility you might still pass. A diesel truck under acceleration is around 86db. I would bet if you're close to the number they would pass you. I mean, think about this in terms of a business model. They are a race track, race cars make noise, a lot of noise. If they have enough business to keep the track up and running most cars must pass or they would go out of business because nobody could pass.

I hope your right. I bought a cheap db meter on Amazon. I will have someone measure from 50 feet away. I will keep you posted. Thanks.

[Synner]

Realize that under load your engine will be louder. You're going to be hosed without bigger mufflers. I get black flagged and can't run at sound limited tracks. You can clamp a turn-up on your pipes to push noise up but it may not be enough. I will eventually find a better muffler for the Hooker system I have. With a cam it's obnoxious.

[CrazyRED]

Originally Posted by Synner

Realize that under load your engine will be louder. You're going to be hosed without bigger mufflers. I get black flagged and can't run at sound limited tracks. You can clamp a turn-up on your pipes to push noise up but it may not be enough. I will eventually find a better muffler for the Hooker system I have. With a cam it's obnoxious.

Sounds like you should be listening to this guy since he's been through it.

That really sucks that you can spend all that money and get kicked for noise. Is it because of nearby residential zone?

[Alex Murphy]

Before I paid for it, I never thought that this would be an issue at a race track. Then they sent me information on how to be ready for the track.

Now Im finding out its big thing at a lot of tracks. If you google "Laguna Seca Pipes" people are adding 90 degree bends from the tailpipe and mufflers behind the rear bumber on Porsces and some other crazy contraptions.

I dont want to reinstall those giant heavy GM cans that came with the car. I wonder how much resonators will quiet it.

[JOHNSONROD]

let us know how it comes out. ive taken sound readings at a race track and 86 is low. ours is 103 db at 50 ft and we still have cars go over. if your car is loud and they take the reading in a place where you are winding third, your over no question. we take sound readings at the loudest places on the track. those things are usually an inked agreement and non negotiable.

[Synner]

Originally Posted by CrazyRED

Sounds like you should be listening to this guy since he's been through it.

That really sucks that you can spend all that money and get kicked for noise. Is it because of nearby residential zone?

It's due to the legal/community zoning and approval process. One is due to church activities on Sundays between certain hours, others are just db limited no matter what due to the approval to get a track there at all.

[Norm Peterson]

Originally Posted by CrazyRED

Sounds like you should be listening to this guy since he's been through it.

That really sucks that you can spend all that money and get kicked for noise. Is it because of nearby residential zone?

Nearby residential zone is the usual reason, and it doesn't even matter if the track was there first.

It's not just road course events that have sound level limits either; there are autocross sites that have sound limits as well.


Norm

[600hp-lpe]

Measurement is taken at a place on track where you would be the LOUDEST - that is where the sound meter gets set up.

85 DB is not leaving any wiggle room. SCCA in Northeast is 91 DB. - borla S cat back (no headers, all the stock cats) and my car is at 90 DB.

here is how we quiet down a loud exhaust for passing scca sound checks -

Steel wool and metal screen material - insert steel wool in the tailpipe tip - use the screen and a screw type clamp to keep the steel wool in the exhaust tip.

You don't need to pack the steel wool - just enough so it baffles some of the noise and doesn't restrict the flow too much.

you will most likely need some exhaust wrap to protect your shiny chrome exhaust tips from wire screen/clamps.

-or-

turn downs on the tailpipe - not recommended if you have nice shiny chrome tips on the end.