Track day Requires 80db. Please Help!!
 

You may have read my previous post regarding noise.

I am looking at a track day at the Mira Testing ground, but in the rules they say that the noise limit is set at 80db.
My Temris I believe are 102db.
I would like to know if I can simply put the standard can back on, without changing the ECU.
Or is there something out there, that quietens the Termis!!!!

Obviously I don,t want to quieten them, but rules is rules!!!!

Please Help.

Regards

Peter G

80db is seriously quiet. Although without knowing how they measure the sound pressure level just quoting 80dB is rather meaningless.

I doubt that many standard bikes can achieve 80dB.

To give you some idea, every increase of 3dB doubles the sound pressure level.

Standard cans will work with the Termi ecu-it will just run a little bit rich. I don't think they can expect you to get it any quieter than road standard.

John

rockhopper

Not sure how they measure it!!!

Have seen a device on here, that was on sale in ebay, that fitted in the end of each exhaust outlet.

However cant find were to get them,

thanks

Peter G

There must be a standard somewhere. You need to know how far away from the bike the noise meter must be and what angle to the bike it should be. And of course you need to know what RPM the bike should be doing at the time. If they measure it with the bike moving then there is loads of chain noise and tyre noise to include.

Chaps, I believe its done 1 meter at 90 degrees from the end of the pipe.

How many revs though?

I have had my 45mm termis on the 748 measured by 2x different tracks, with what seemed to be the same meter, at about 4,000 (?) and one read 102, the other 98.
Either way I was allowed out - just!
80db is unmanagable on a Duke I'd say with standard pipes.
Get them tested maybe?
Donington and Oulton Park certaintly have the kit.

Best of luck

Tim

ps - try a search such as "db meters" on Google - came up with
http://www.gracey.com/prod-07b.htm

[Edited on 3-9-2004 by aws]

It's an SPL meter you want, Maplins do them for about £50

http://www.maplin.co.uk/products/mod...1&P roducts=1

The standard cans are stamped as complying to the 80dB noise requirement, so you should be fine with these.
http://www.chathamclose.com/pics/endcan.jpg

The standard test for road use is a top gear drive by at around 60 mph, whereas circuits tend to measure at 3/4 redline 1m from the exhaust at an angle of 45degrees. I'd suspect MIRA would use the driveby test becuase of who they are and the low limit they've set.

This is why most standard cans on most roadbikes score well into the 90's at circuits, even though the noise limit for road use has been 82dB since '91 and most manufacturers (inc Ducati) work to the tighter US EPA regs with a limit of 80dB.

I got sick of my standard piped R1 failing noise tests, so did a bit of digging into why the figures don't match up, even bought my own SPL meter to dispute the uncalibrated units at Goodwood & Castle Combe.

The dB or decibel is a logarithmic scaling of the sound pressures we hear.

The actual pressures we can hear is enormous 10 bars = 114dB rather loud right down to 20 microbar = 0dB, the threashold of hearing. Barometer also measures pressure in bars or millibars

To discuss values from a few millionths of a bar up to 10 bar was difficult so they decided to convert the measured pressures into logarithmic values and so finished up with values of 0 - 12 bels

This was reduction down to 12 steps was a bit too crude, so they simply multiplied the values by 10 and got the usual sound range 0 - 120 dB [threshold to pain]

An increase of 3dB = twice as much acoustic power or watts. If you have a klaxon of 80dB and you put another one next to it a sound level meter would read 83dB because it's a logarithmic scale not 160.

But you ears would not perceive the 2 klaxons together as being twice as loud as ears are non linear. In practice a 10dB increase 'sounds' twice as loud although the acoustic power or energy is many times that.

For the same reason, an increase of 1dB is difficult to detect by ear

Hopefully you are not totally confused.

A simple and effective meter to use for m'cycle exhausts is something like the Nor 102. Meters like this cost £1000 or more. You can buy meters from Maplins etc for as little as £60 but they are indicators not meters