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Thinking of doing a track day or two over the summer, and the organisers tell me that entrance is subject to the my car producing less than 105 dB of noise. This is a standard 'race' noise limit they say.
I have a MY97 Turbo with K&N induction kit, straight-through Magnex centre section, and Scoobysport backbox. Is my car going to be too loud? If so, what should I put back on in order for it to meet the noise limits? Thanks in advance! Andrew |
Andrew, you will be fine on that setup IMHO. Most track days run at 98DBa which is the legal maximum for a vehicle on the road.
Your setup should be below 98Dba unless it is old and has had the packing material burned. |
Cheers John. The system is less than 6 months old, so (fingers crossed) should be okay. From what little I know about decibels, 105 db is considerably louder than 98 anyway.
http://bbs.scoobynet.co.uk/smile.gif A. |
When i used to grasstrack with a class 9 special we had to be below 105 to pass noise test and i have yet to hear any scooby that comes anywhere the noise a open mounted pinto with tiny exhaust made and it allways passed.
Andy H [This message has been edited by Andy H (edited 16-05-2000).] |
yep, DB's are a logarithmic scale. 105DBa is very loud. 6DBa doubles the noise level. We just get 105Dba with our race esprit and that is Loud.
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I should have known! http://bbs.scoobynet.co.uk/wink.gif The one that was considered "too loud" by the people living near MIRA!
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AH, my old 350BHP 2wd cossie, now that was a fun, LOUD car.
Havent got a clue how loud that thing was, thats why i mentioned the packing material, as my flame outs melted all mine. http://bbs.scoobynet.co.uk/biggrin.gif It was quiet until i started to use full throttle at 7200RPM, sounded quiet in the car though http://bbs.scoobynet.co.uk/wink.gif My westie has a repackable silencer for when i melt that one http://bbs.scoobynet.co.uk/biggrin.gif |
How loud was that Cossie then John? http://bbs.scoobynet.co.uk/wink.gif
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which cossie david?
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John,
thought it was generally thought of as 3DB to double sound pressure level? 10 decibels is 10-fold increase, but that works only for 10, the base of the decibel system. 20 decibels is 100-fold (10x10), and an increase of 5 decibels is an increase by a factor of the square root of 10. Your handy pocket formula http://bbs.scoobynet.co.uk/smile.gif for power: 10 log(P2/P1) although Im confused as to how you actually work that one out! robski |
robski,
I have heard that said many a time about 3DB being double. However i worked for years using ultrasonic high acuracy testing equipment on aircraft engines and in the nuclear industry and a 6DB gain is always classed as double the energy when using ultrasonics. So either there is a different scale for ultasound to sonic (which i doubt) or there is some duff info out there? |
OK, its been bugging me so i did a bit of research. We are both right in some ways robski.
In audio apps 3DB is double the sound energy. The reason i was confused on this issue is that with the kit i used, it was using voltage power as a reference, in this app a 6DB gain in amplifier power gives double the energy. As all my instrumentation used high energy ultrasonic probes driven by amplifiers. The instruments scaleing is done in 6DB gains. So i have been going around for at least 15 years with the wrong scale in my head for audio power levels. http://bbs.scoobynet.co.uk/redface.gif http://bbs.scoobynet.co.uk/rolleyes.gif we learn sommat new every day. http://bbs.scoobynet.co.uk/biggrin.gif [This message has been edited by johnfelstead (edited 17-05-2000).] |
John,
I think you want this one! for voltage: 20 log(V2/V1) still dont know how to use them tho! robski |
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