Question about noise testing at Bedford

[aww999]

Hi guys, I have just roped the missus into noise testing my MR2 prior to my first track day at Bedford next week. It has a stainless exhaust on it (fitted by the previous owner) which is louder than a standard car. Tests were done at 0.5m, 4500 revs, which is how Goldtrack describe the static test in the paperwork they have sent me.

First test: meter set to "Fast" response, and "C" weighting 106db!

Second test: meter set to "Slow" response, and "A" weighting 96db

Obviously a pretty big difference, and as the noise limit is 101db it is the difference between pass and fail. Can anyone tell me what the "weighting" setting does, and which is most representative of the test that is carried out at Bedford?

I am going to email the circuit as well, and see if there is an opportunity to get them to test the car before the event.

[Mutton]

Bedford, along with all other circuits test to A weighting. I was at Bedford on Friday and measured 86dB static, which is way under the 101dB limit. However I got warned for being right on the limit of the 87dB drive-by limit (measured at approx 20 metres) within about 5 laps of being on the circuit, so had to back off slightly when I got close to each of the four mics placed around the GT circuit. Better to do that than get black flagged after a handfull of laps!

[raceboy]

I'm getting a little nervious about the noise testing, booked at Bedford for next Monday and never really looked into the noise limits but my car is a little on the loud side so I'm putting a lot of faith in my trackday cans, but I'm half tempted to take the daily driver as it's a long drive to stand about and watch if I get blacked flagged on the 1st lap.

[Chris71]

I was very nervous about my last trip to Bedford, but everything there - a TVR Sagaris included - got through the noise test.

[Scarpia]

I have been black flagged in a 997 GT3, but I have seen other GT3s at Bedford since, so looks a bit random to me (maybe weather conditions and state or the car not to mention measuring device play a role). No problem in the Exige 240 (standard exhaust). Generally speaking if you have a modified exhaust or drive something loud such as GT3 or TVR you run the risk of being sent home.

[raceboy]

With my trackday cans fitted I have no problems with Doningtons strict 98dB on track limits so I'm going to risk it.

[monkey636]

I was at Beford last Friday evening; I registered 104dB on static so they took my car out for a test run on the drive-by and it passed, and no black flag for the entire evening. I think it's a bit subjective on the exhaust, wind, gearing etc.

Charlie.

[raceboy]

I've borrowed the company noise meter so tonight I'll be measuring the static noise levels with and without the trackday cans.

sorry neighbours

[Chris71]

raceboy said:

I've borrowed the company noise meter so tonight I'll be measuring the static noise levels with and without the trackday cans.

sorry neighbours

Be warned no two meters seem to read the same. My first DIY sound test came out the best part of 8dB below MSV's!

[Club MSV]

This might help: http://www.clubmsv.com/car-trackday-noise-limits.a...

[raceboy]

Noise test complete, and it's not looking good.

Considering the magic number to be under is 101dB....

at idle the car sits at 102dB.....when you fire it round to 4500rpm we get a steady 116dB!

So.....after fitting the trackday cans.....

at idle we now have 84dB......but reved up to 4500rpm it sits at 102dB.

Which to me is a little to close for comfort considering it's a 1 1/2 hour drive there and the cost of the trackday to be considered so the trusty daily driver BMW is getting it's first track outing, which incidently hits 87dB AT 4500rpm.

[mikey P 500]

i have had a car tested there before i booked a track day and they seem quite helpful about checking this, as said though the main problem is the drive by tests (which they will also offer to test for you before you book).

[aww999]

I managed to pick up what I thought was a standard exhaust for £45 (turns out it's actually a Mongoose stainless steel jobbie) which has a rear box twice the size of the magnex one. I've just spent a couple of entertaining hours on my back swapping them over, and the car is a *lot* quieter now, so I should be able to enjoy myself on Monday without worrying about getting sent home for being antisocial