Too Loud

[stush]

Had the car up for inspection in CT.

Failed as they said it was too loud. Registered 81dB and the limit by their stanard is 78dB. Any ideas how to bring it down.

Also said there was too much "play" in the steering. I have a Jaguar front end and Jag core steering rack How does one go about getting it tighter?

Stu
(crying in CT)

[Dangerous Doug]

I've heard of guys stuffing a little steel wool in their pipes to quiet them down. I figure, wad some up with a wire tied around it so you can extract it later.

Some steering boxes have an adjustment to tighten up the play in the steering. On my chebie in high school, this was a small screw with a lock nut.

Good luck.

DD

[stush]

I have heard of the steel wool trick as well, I suppose keep it attached to a wire and push the wire in al little so it doesn't stick out.. Then hope when you hit 3500 rpm's, the steel wool does not come flying out. Any tricks to stop that from happening? The steel wool itself won't melt?

Stu

[stush]

Same idea as spiral turbo baffles. But they are rigid and each end of my pipes are curved(from headers and exit) so would not be able to get them inside without cuttung and reweilding. Unless I am missing something.

Does anyone have experience with Supertrapps of the Dynatech conical design?

Stu

[stush]

I meant Supertrapps or the Dynatech conical product.

Stu

[jarendall]

I have the vortex cones form Jegs, I don't know how much they quitened it down, but it did tone it down a little, might be enough

[stush]

What would happened if I wadded up some steel wool and then put a Vortex cone in. Cone would keep the steel wool from flying out and may reduce sound further??. Any idea if the steel wool would melt from the heat?

Stu

[Don]

Stush:

Go to the following Thread and contact Mike, his posting


" For 1 day I wish I had quiet pipes. Borrowing a set of trapps and heat shield for the exhaust that my friend just went through a couple of weeks ago and had no problems. He's got a 427 SO as do I but mine is stroked. I'll update everyone on here. Tell your friend if he wants to meet me there @ 7:45am (I know loooonnnnggg day) he can and at least see me go through the fire first."

-Mike

Connecticut: Registration, Inspection & Emissions

Bolting on the trapps as Mike suggests might be an alternative, but I am not aware whether Mike passed his inspection. The CT DMV standards are " Maximum Permissible Noise Levels for Vehicles "

Are glass pack mufflers legal?
" Per Sec. 14-80a-1a through 14-80a-10a of the DMV Regulations for "Glass Pack Mufflers" it is based on the loudness of the vehicle measured in accordance with the DMV Regulation. The loudness is affected not only by the mufflers utilized, but also by any engine modifications. There can be two different vehicles with the same exhaust system, however, they may have different engine modifications. One of the vehicles will pass the noise level measurement test and the other vehicle may not. "

Within the specs are the specific measurable standards which need to be followed when measuring the dB level and the actual dB allowed:

Sec. 14-80a-1a through 14-80a-10a

If the measurment was taken within the enclosed inspection lane, my guess it would be louder than outside, due to the sound bouncing off the walls. If I can find the CT DMV web link again for the SEC. mentioned above, I will post. I " think ', but am not sure , the Vortex cone is more effective if placed closer to the primary extentions and before the muffler. For this reason, the trapps might be a better starting point. The point of the cone needs to be inserted towards the engine.

Don

[Don]

Stush, use the follwing link and scroll down to the reference on " Are Glass Pack Mufflers Legal" There is a link to the pdf which contains the SECs I mentioned on Permissible Noise Levels. The question might be if the Inspectors followed the correct procedures in case the trapps or other modification does not reduce the dB level.

http://www.ct.gov/dmv/taxonomy/site_index.asp?dmvNav=|

*** For some reason, I cannot copy and paste the link to work, will look for another path, might want to try inserting the web link above into your browser..................
Don

[jarendall]

I welded my cones in, they come with bolts for bolting in, you might could pack in stainless steel wool and then bolt in the cones and that might work

[stush]

The sound test was done outside. I parked in an area just to the right of the entrance into an inspection lane and he had a decibel meter. I came armed with the state stautes. He walked behind the vehicle on to the grassy area and did his measurements from there. The statutes says 50 ft. I did not pull out my tape measure but I would say he was the correct distance. As the Supertrapps are removeable, I am interested to know if thatey were accepted and did your freind pass inspection?

Stu

[dsmith]

Stu

I am in Newtown and am in the process of getting my Cobra registered. Was the car titled in another state or is it a new build?
If you care to call me, I can tell you what I am doing 426-3141 days
648-0548 eves.

david smith

[Don]

Stu, I do not know Mike personally, but only from his posting, might want to send him an e-mail or PM using the info in his Profile.

I did check CT DMV Section 14-80a-4a , Allowable Noise Levels since Jan 1, 1979. The maximum dB for a stationary test is 72 dB for soft site( grass ) and 74 dB for hard site ( pavement ). Section 14-80a-9a mentions the distance for measuring the dB. The baseline is 48 feet or more but less than 58ft. An adjustment to the dB reading is made up or down for readings either closer or farther away than the baseline range. The max reading is 81 dB for a hard site, highway operation above 35MPH, using the 48 to 58 ft baseline for measuring.

[stush]

I have my own dB meter and I know at idle from my measurements I am fine. They then have you rev it in neutral and do another measurement, presumably what they are equating to 35 mph. I will have to PM Mike cuz I heard from someone that they may not accept Supertrapps.

Stu

[Don]

Stu, curious on the procedure the DMV is using for the 35 MPH test. Did they have you hold the RPM at no higher than the equivalent of 35 MPH in the highest gear ( 4th, 5th, ) or just rev the engine w/o any regard to the peak RPM.

Not knowing what type of dB meter the DMV is using, some models can be set to hold the peak dB recorded as the high which might be above the equivalent of 35 MPH @ 50 ft. in high gear.

Might want to check with Jay @ Vintage- Motorsports in Middletown., 860-790-0987. I think he indicated in another Thread that the Backdraft Cobra passed the dB test w/o the use of trapps.

With the CT emissions standards for Composite/ Kit Cars being tightened as of January 1, 2007 for new registrations and now the use of the dB meter, additional challenges to register in CT.



Don

[Hans-Olof Blom]

In Sweden the measurements are done during full acceleration. The person doing the test will drive about 30mph in second gear and approx. 30ft before the measuring point he floors it. The allowed level is 85dBA.

I stuffed my side pipes with 6 steel wool balls in each pipe and added a plug made from expanded metal to keep everything in place. See pictures!

I adjusted the carb linkage so pedal to metal was only about 70% of full throttle.

My Cobra was really quiet and when I heard it during the test I was sure it would pass.

BUT, I was told to come back and WITH mufflers. The measured sound level was 90dBA so it was not even close.

After my first attempt last fall the weather was too bad for another try. But within a qouple of weeks I will try again. I have now added a construction made of Al-discs on a wire with tubes as spacers. It is now very very quiet but a bit hard to start.

[stush]

the test was done stationary with revving the engine in neutral...not what I feel is truly accurate if that is there equivalent for 35 mph. At idle I know from my own meter I am around 67dB. On my own testing I was around 81-82 or so in my driveway at 50 ft.

Stu

[stush]

excellent pictures. How do you keep the plug in place? is everything threaded over the long wire/cable?

Stu

[ezplans]

Sweden, Even Kalifornia doesn't clamp down like that. At one of my BAR appointments my quiet car was 115db at 2500rpm, can't image what it would be hitting it in 2nd. All I know is that all the police officers I've encountered just smile. Just luck, maybe. Bill

[Ant]

We are about to get a decibel test here in NZ probably about 90DB measured 0.5 M away from tailpipe, this is going to be a problem for my engine, so heres what I intend on doing,

Fit an auger/three disc chambered baffle into the tail pipe, they are easy to fit into 3" or 3.5" curved tailpipes, but the insert baffle can only be probably max of 8" long total, and can be made to fit around the curve pending shape - anything is possible, even if you use three big washers and have the gas into the center of the first one out a cut out in the through pipe then through a series of holes in the next washer, and then back through a cutout in pipe and through center of the exit washer. This works motorcyle guys have them and I used it in my first Cobra, and for obvious reasons it doesnt help performance!

As I am going to probably use more than one exhaust pipe per side underneath the car it will be harder to fit a baffle but I guess its all relative.

Under floor systems, face the exit downwards and slightly inwards to center of car.

Have a 3000 chip in your MSD so they cant rev your engine to the required 4000rpm when you get pulled over, I have an adjustable dial type MSD which will be in easy access while driving.

Drive really quietly around town and let them get used to you, as I only live in a small town that may work.