Discussion
I have two cars I want to take on track to Bedford Autodrome but I am unsure if they will pass the noise test. It will be an expensive non-event if I get there and they get turned away.
Is it possible to do a reliable test with a noise meter on your driveway? If so what meter would be good enough without spending loads of cash?
Is it possible to do a reliable test with a noise meter on your driveway? If so what meter would be good enough without spending loads of cash?
I did a Bedford trackday last month in my TVR Chimaera. I was worried about the low noise level 101 static. I got a bit paranoid in the end ,so I bought a noise meter ,only 20 quid off fleabay. New Silverline . Took my car to an open area nearby, (so not to get any noise bouncing off buildings etc) . The reading I got on my meter was pretty spot on with the reading they took at the track .
For the sake of 20 quid ,its better than losing the trackday money.
For the sake of 20 quid ,its better than losing the trackday money.Stephanie Plum said:
Static isn't the key at Bedford - it's drive by. 101 db static is relatively generous - 87.5 db drive by isn't and that's what fails the majority there.
Yes very true.But the very nice Bedford track chap who gave us the briefing ,also gave us the heads up as to where the mics were on the track .seeby said:
Yes very true.But the very nice Bedford track chap who gave us the briefing ,also gave us the heads up as to where the mics were on the track .
did he say that they would show the noise boards to cars that were getting close to tripping the meters???a friend of mine got black flagged at 1030 and asked to leave, they said his car had been getting noisier all morning, but didn't bother to show him the flag and warn him.... its his local track but had changed one thing since he was last there...
enduroboy said:
seeby said:
Yes very true.But the very nice Bedford track chap who gave us the briefing ,also gave us the heads up as to where the mics were on the track .
did he say that they would show the noise boards to cars that were getting close to tripping the meters???The noise meters are pretty obvious, and are sited (on the GT circuit at least) in the acceleration zones after reasonably slow corners. Just back off a tad and/or short shift past them and you probably won't have any problems - at least, that's what I do in my exige and I haven't had any problems thus far. They main ones that can cause issues are the one just after the hairpin at the end of the pit straight and one in the back complex that is much closer than 20m away!
Stephanie Plum said:
Static isn't the key at Bedford - it's drive by. 101 db static is relatively generous - 87.5 db drive by isn't and that's what fails the majority there.
Surely the have at least taken an educated guess that one will roughly equate to the other. I.e. they know what their drive-by limits are so tgey set their static limit to be realistically in line, even allowing a little leeway.
I doubt 101db is arbitrary.
Ellerslie said:
Stephanie Plum said:
Static isn't the key at Bedford - it's drive by. 101 db static is relatively generous - 87.5 db drive by isn't and that's what fails the majority there.
Surely the have at least taken an educated guess that one will roughly equate to the other. I.e. they know what their drive-by limits are so tgey set their static limit to be realistically in line, even allowing a little leeway.
I doubt 101db is arbitrary.
Ellerslie said:
Surely the have at least taken an educated guess that one will roughly equate to the other.
I.e. they know what their drive-by limits are so tgey set their static limit to be realistically in line, even allowing a little leeway.
I doubt 101db is arbitrary.
sorry but it is not like that at bedford at all.......I.e. they know what their drive-by limits are so tgey set their static limit to be realistically in line, even allowing a little leeway.
I doubt 101db is arbitrary.
a csl will pass static at 101dB all day long but will not pass driveby due to the airbox under load.............
mad4amanda said:
Its part of the due dilligence shown by the curcuit to noise control
Exactly, so there will be some correlation between the static and drive-by limits. The static limit will not be a number pulled out of thin air I'd hope. I'm sure there are going to be cases of cars passing the static limit but failing the drive by due to the engine etc being under load as said. In the case of Brands, perhaps the highest static figure still passes the drive by. Or perhaps they lower the static figure dependant on the amount of cars they are expecting on track at any one time etc.
Bedford claim that a static test of 101db at 3/4 RPM is mathematically the same test as 87.5db at 20m with the engine at or near the red line.
However, by way of an example, I had a different exhaust on my exige at one point and did at TD at Bedford. Passed the static test at 93DB, but failed the drive by at 88.6db. Then had it retested by them (static) and made only 92.5db. So make of it what you will. I now have a different exhaust and have not had any further issues when I've gone back there, although I'm always especially careful in the morning.
Either way, it's a planning condition that they have to satisfy, so whether the static and drive by limits make sense is outside of their control. They are allowed a limited number of breaches per year, which they mostly use to test F2 cars.
However, by way of an example, I had a different exhaust on my exige at one point and did at TD at Bedford. Passed the static test at 93DB, but failed the drive by at 88.6db. Then had it retested by them (static) and made only 92.5db. So make of it what you will. I now have a different exhaust and have not had any further issues when I've gone back there, although I'm always especially careful in the morning.
Either way, it's a planning condition that they have to satisfy, so whether the static and drive by limits make sense is outside of their control. They are allowed a limited number of breaches per year, which they mostly use to test F2 cars.
Ellerslie said:
mad4amanda said:
Its part of the due dilligence shown by the curcuit to noise control
Exactly, so there will be some correlation between the static and drive-by limits. The static limit will not be a number pulled out of thin air I'd hope. I'm sure there are going to be cases of cars passing the static limit but failing the drive by due to the engine etc being under load as said. In the case of Brands, perhaps the highest static figure still passes the drive by. Or perhaps they lower the static figure dependant on the amount of cars they are expecting on track at any one time etc.
Its the driveby that is ultimately the figure that determines the continued use of the curcuit but as this is affected by too many variables the static test provides a baseline to work from . To give you an idea of the scale of the issue most curcuits have multiple noise meters in high acceleration/rev zones to provide cover, these are monitored constantly both by computer and by a person to differentiate between say a group of traffic or a loud vehicle.
Yesterday at brands the daytime limit was 105 the evening 102 so if your doing day and evening be prepared to have a fixed means of quieting your car a db killer of the right size is a worthwhile edition to a trackday kit and may pay for itself in the long run.
There is a limit to the number of noisy days that any curcuit can run as part of the agreement with the local council and after a noisy meeting there are often designated quiet days such as a driving expearience.
The noisy days are often used for race or test days and so are at a premium for track days especially say on the brands GP track.
Quiet days tend to be cheaper but of course you need to be ready to meet the lower level ,a can that has been cut down or never repacked is unlikely to meet the requirement sometimes even with a baffle fitted.
Edited by mad4amanda on Wednesday 3rd April 13:43
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