Sound DB levels (race track BAN)

[Excaliber]

With the various race tracks really cracking down on DB levels it is getting tough to meet the sound requirements to get on the track. Some tracks are more lenient than others, but most all of them have an allowed sound level.

My Cobra IDLES at 106 DB (as read from the drivers seat). 95-103 is about max allowed and varies from track to track, typically measured at 50 ft, sometimes a 100 ft. I THINK the measured DB is taken at track side with the car moving down the track, which would be a much higher DB than idle.

I called Supertrapp and they don't have any readily available solution. Anybody got any ideas on what to do? I'm considering replacing my existing side pipes with "something" that is quieter. A loss of horse power is better than NOT being allowed on the track at all!

[dcdoug]

Wow, are you kidding me? Our cars are legal on the street but banned on tracks because they make too much noise? What is this world coming to? We are becoming a nation of sissies.

If it's because of nearby residents, then maybe they should have considered noise BEFORE they moved near a track. That's like people who buy homes near the airport complaining of noise (Did they ever wonder why their house was less expensive?)

[wrogers55]

Check the sprint car racing community. They too have been hit hard with sound requirements, some as low as 90 db. And that's on an alcohol burning 850 HP race motor. They solved it but the cars sound more like really fast vacuum cleaners than race cars.

I owned the racing school at Laguna Seca in Ca when sound became a major issue for road courses (track days for Cobra guys). The level for professional racing was lowered to 101 db (including Indy cars) and schools were set at 85 db. Our factory pace cars couldn't meet the 85 db limit at full throttle, but the race cars could. It was disgusting. We finally settled on a system that uses something that looks like the old cherry bomb muffler, but inside is an augur looking thing that spins the charge and there is a noise cancellation effect. It's a commercial product, I just can't recall the name. It worked pretty well, with several Supertrap discs mounted on the end.

Also, if there is a standard position for the sound microphone at your track, you can use that to your advantage. The Cobra produces sound on each side without a cross over and only exposes the dual notes from behind, as the car has passed the microphone and getting farther away, which is the biggest help. You might be surprised if you make something that will aim the tip of the exhaust at the track surface to take a lot of energy out of it before it get in the wild. The other side might not be having much of an impact, depending on the location of the microphone.

But, I think the sprint car guys have pushed the technology lately and really have it down. They use little "suit case" stainless steel boxes at the end of the headers (very Cobra like headers) and that does the trick for them. Borla, as I recall, might be the manufacturer. Good luck, I suspect this will only get worse as time goes on.

Good luck,

[Cobra #3170]

Flowmaster has developed a muffler for sidepipes that should meet most track DB limits. They are 35" long including 3.5" connectors and should fit most Cobras. You would need to weld a turn out on the muffler and then an attachment system for both the collector and the muffler mount. They are making them in their Idaho R&D center. A little pricey at $199 each but worth it if you want to run.

Originally Posted by Excaliber

With the various race tracks really cracking down on DB levels it is getting tough to meet the sound requirements to get on the track. Some tracks are more lenient than others, but most all of them have an allowed sound level.

My Cobra IDLES at 106 DB (as read from the drivers seat). 95-103 is about max allowed and varies from track to track, typically measured at 50 ft, sometimes a 100 ft. I THINK the measured DB is taken at track side with the car moving down the track, which would be a much higher DB than idle.

I called Supertrapp and they don't have any readily available solution. Anybody got any ideas on what to do? I'm considering replacing my existing side pipes with "something" that is quieter. A loss of horse power is better than NOT being allowed on the track at all!

[RodKnock]

Originally Posted by Cobra #3170

Flowmaster has developed a muffler for sidepipes that should meet most track DB limits. They are 35" long including 3.5" connectors and should fit most Cobras. You would need to weld a turn out on the muffler and then an attachment system for both the collector and the muffler mount. They are making them in their Idaho R&D center. A little pricey at $199 each but worth it if you want to run.

Allegedly, the sidepipe mufflers that I have, produced by Hushpower, a division of Flowmaster, meet the current track requirements. I like them, but I haven't tested them out a track. I wonder if the mufflers you mention are the same ones that I'm running. Hmmm.

[RodKnock]

I will add that 4pipes (Dave) has the same ones on his blue Kirkham and he runs without issue at the tracks here in NorCal.

[Excaliber]

That's an excellent tip on the FlowMaster side pipes. I've been calling flowmaster since I read the post, can't get through for some reason. Called a local flowmaster dealer and he had no clue what I was talking about. My sidepipe bolt to the collector outside the car, should be fairly simple cutting off the old muffler/sidepipe and welding my flange to a new one to "bolt on". If I can find the right side pipe/muffler. At $200 per unit, I'm not interested in chancing it will work, I'd like to KNOW it would.

[4pipes]

Originally Posted by RodKnock

I will add that 4pipes (Dave) has the same ones on his blue Kirkham and he runs without issue at the tracks here in NorCal.

I've never tried running at Seca with the Kirkham. Wouldn't even try. My stock Ferrari couldn't even complete a session without getting the meatball. Some cars would get flagged at Seca from transmission noise! Most people just lift off the throttle when going up the hill by the sound shack between 5 and 6.

I do love the Hushpower mufflers. They seem to take the nasty high pitch edge off the noise without sounding girlieman.

[4pipes]

Hushpower:
http://www.hushpower.com/news.php?nak=55

[Gunner]

Originally Posted by dcdoug

Our cars are legal on the street but banned on tracks because they make too much noise?

I'd bet that any car too loud for a track is too loud for the street in most jurisdictions - it's just not enforced very much, and then only for screaming high-pitched fart cans on ricers. The solid roar bigger engines make at reasonable revs is not as annoying unless it's continuous.

106 dB in the driver's seat? I just about guarantee that's not legal in many places.

[Excaliber]

Oh I drive real careful like around town and near my house! Keep the rpm's down, short shift, back off the throttle if I smell trouble.

Now in YOUR neighborhood, I'm liable to leave big black marks, wind it out and be a hooligan in general. Where was it you said you lived?

By the way, I DO wear ear plugs, have for years, I keep several sets (new and used) in the glove box at all times.

SAAC 35 comin' up at Infineon, rumor has it the track is fairly strict about noise. I think it's going to be a problem for a lot of cars.
COMPUTERWORKS, make a note! How are they going to enforce the sound level checks at SAAC 35?

[FWB]

never heard of such a thing as noise restrictions at a track. i guess i'm sheltered from that stuff here in PA. i have slip ons that i stick on instead of the header mufflers. they are just a collector extension straight thru with a turn out. so do you get an environmental fine if you spin the tires and make smoke? ....

[Don]

Lime Rock Park in CT has sound/noise restrictions, do not recall the db level, and has had for a number of years, along with no racing on Sunday. One of the other differences is how the measurement is taken, at full throttle/speed and at what distance, measuring device on grass/dirt or pavement.

[Excaliber]

Under the RULES section from the NorCal Shelby Club site:
4.1.11 MUFFLERS
Mufflers are required on all cars. The exhaust system must be able to meet the sound limit for the venue: Laguna Seca - 90dB(A), Infineon Raceway - 103dB(A), Thunderhill - 105dB(A). No open exhausts will be allowed.
Note: For Thunderhill exceptions to this rule may be made on a case by case basis, at the discretion of the chief steward or event organizer. There are no exceptions at Laguna Seca or Infineon Raceway.

Apparently the DB reading is taken "at speed" while your on the track.

Exhaust Systems That Don't Work (from the Web Site).

• Open exhaust, obviously doesn't work!
• Glasspack mufflers do not work!
• 3 inch pipe Flowmasters don't work!
• Flowmasters with center inlet or center outlet don't work!
• 3 inch pipe or larger Brand-X mufflers don't work!
• Shorter than 28 inch LoBaks don't work!
• Race style LoBaks don't work!
• Borla mufflers without catalytic converters or without a secondary muffler such as a Supertrapp don't work.
• Monza style exhaust or European high performance mufflers on Ferrari's, Porsche's, etc., don't work.
• Stinger type of exhaust on Porsche's & Mazdas, commonly known as expansion chambers, don't work.

107-110 DB is pretty common for a "Cobra" at highway speed. From what I have found so far you can only expect a FEW DB drop with things like "Supertrapp" exhaust tips, cone inserts, etc. The NorCal club is looking for any ideas that might help, they DO NOT have a 100% solution at this time for Cobras. GT-350's and various street cars are in the same boat with the noise issue.

[dcdoug]

I understand not allowing open exhaust. The rest of it is BS.

[Don]

Lime Rock Park in CT didn't have too many alternatives to appease the neighbors , in today's world/society, better to regulate than risk the possibility of not having any racing.

[1985 CCX]

I have friends in the same bind, cars can't be run since volume DB is too high. Seems crazy that a street legal car is track banned for sound. Local ordinaces and libs...........

I am sure within 5yrs this will be a major set back for Eastern tracks as they are usually close to population. Bummer

[badrich]

I started out with a mild 390 with stock (burned out) glasspacks and it was kinda loud and raspy. When I went with my nasty big block it got to be *real* loud and raspy. My next door neighbor looked at me like she was going to hurt me when I wasn't looking. Reluctantly I changed over to 24" Race LoBaks and those funny little cones. A little quieter and less raspy. That's as good as it gets. I still use my ear plugs, but if I forget them on a short trip for breakfast, my ears aren't ringing when I get there.

I plan on running the autocross at Sears Point for SAAC 35, but will be real hurt if I get black flagged. I *might* consider the track, but am afraid my beast is faster than I am. We'll see. Rich

[dcdoug]

The strange thing to me is that I would think the tracks were there first and then people got pushed out toward the tracks. You move near a race track, don't ***** about noise. It's your fault, not the track's. We just live in a society where no one wants to take responsibility for the consequences of their actions. It's always someone else's fault.

[Don]

CT does have very specific regulations regarding noise levels of autos and trucks, but not aware if ever enforced. One reason, the complexity as outlined in the regulations of measuring and equipment required. Technically, the noise standards are part of the Inspection process.

At Lime Rock Park, motors cannot be started until 9:00 AM, which is vigorously enforced, to the point that 8:59 AM is too early. Might hear over the PA system, whoever has started the engine, shut it off.