Drive by noise limits

Drive by noise limits

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Yazza54

Original Poster:

18,493 posts

181 months

Sunday 14th January 2018
quotequote all
Morning all

I’m intending to do some racing this year in the 750MC in RGB, bought a second hand Spire before Christmas and have been doing some bits on it over winter to get it ready (documented on a readers cars thread).

The first race is Donny toward the end of March and as such I’m desperate to get out in the car beforehand. Not necessarily too bothered about it being at Donny, mainly just to make sure if there’s any problems or things I’m generally not liking I can sort them before the race weekend and obviously to give me a chance to see how it drives first - jumping in at the deep end somewhat!

I was either going to take it to Oulton with that being my most local or Donny for obvious reasons. Main issue here is the noise limits - I’m having a longer can made with a removable baffle so I’m quite confident the static test will be no bother which is 105db at Oulton - but the drive by is 92db!

Now on the face of it that sounds very quiet but from reading up I’ve found more people complaining that Donny is actually worse (no static and 98db drive by).

So what’s the score, is it measured from further away at Oulton and therefore not comparable? I’ve read a few stories of people passing at Oulton no bother and not pinging any of the drive by meters only to fail miserably at Donny at what, on the face of it at least, should be easier to pass?

If anyone has any info that would be great, also before anyone says, test days are not on good dates for me and are ludicrously expensive so I really need to try and get the thing on a general TD.

Cheers

E-bmw

9,189 posts

152 months

Sunday 14th January 2018
quotequote all
I have no specific experience of noise issues at either being as I have always been well silenced & in different cars to yours but in general if you ask around (cue other replies on here) you will get to know where the drive-by is & just back off slightly/short shift at that point, your time losses over the lap (which you aren't taking anyway as it is a TD) will be virtually un-measurable.

4.7

155 posts

170 months

Sunday 14th January 2018
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Donny meters are closer to the track. I reckon your car would need to be closer to 101db static. Watch out for induction roar or side exit exhaust that aims straight at it too.

smiles1

543 posts

222 months

Sunday 14th January 2018
quotequote all
Could you do a testday instead which (dependent on circuit) should have a higher noise limit?

Yazza54

Original Poster:

18,493 posts

181 months

Sunday 14th January 2018
quotequote all
As I said in my opening post the test days are not on particularly convenient dates and they’re about 3x the price of a general TD.

Reading up the general consensus is that at Oulton at least, if you pass the static you should be OK. I’ll throw my new can on in the week and do a test with and without the baffle. Pretty confident about the static was just worried about the drive by with it being such a seemingly low figure, but again as I’ve researched the figures for drive by are not comparable from track to track.

Think I’ll just have to give it a crack. When I was at Oulton doing my ARDS there was a proper Audi R8 race car amongst some other tasty stuff that you could hear half way round the track and no one batted an eyelid!

Edited by Yazza54 on Sunday 14th January 21:36

CrutyRammers

13,735 posts

198 months

Sunday 14th January 2018
quotequote all
Yazza54 said:
As I said in my opening post the test days are not on particularly convenient dates and they’re about 3x the price of a general TD.

Reading up the general consensus is that at Oulton at least, if you pass the static you should be OK. I’ll throw my new can on in the week and do a test with and without the baffle. Pretty confident about the static was just worried about the drive by with it being such a seemingly low figure, but again as I’ve researched the figures for drive by are not comparable from track to track.

Think I’ll just have to give it a crack. When I was at Oulton doing my ARDS there was a proper Audi R8 race car amongst some other tasty stuff that you could hear half way round the track and no one batted an eyelid!

Edited by Yazza54 on Sunday 14th January 21:36
I've passed the static at Oulton then been black flagged for noise when on track. But shifting up 500 rpm earlier sorted it, so if you do trigger the drive by, it's not the end of the world.

Yazza54

Original Poster:

18,493 posts

181 months

Monday 15th January 2018
quotequote all
CrutyRammers said:
Yazza54 said:
As I said in my opening post the test days are not on particularly convenient dates and they’re about 3x the price of a general TD.

Reading up the general consensus is that at Oulton at least, if you pass the static you should be OK. I’ll throw my new can on in the week and do a test with and without the baffle. Pretty confident about the static was just worried about the drive by with it being such a seemingly low figure, but again as I’ve researched the figures for drive by are not comparable from track to track.

Think I’ll just have to give it a crack. When I was at Oulton doing my ARDS there was a proper Audi R8 race car amongst some other tasty stuff that you could hear half way round the track and no one batted an eyelid!

Edited by Yazza54 on Sunday 14th January 21:36
I've passed the static at Oulton then been black flagged for noise when on track. But shifting up 500 rpm earlier sorted it, so if you do trigger the drive by, it's not the end of the world.
Good stuff, hopefully I’ll get on OK. Where’s their noise meter located then?

Wh00sher

1,589 posts

218 months

Monday 15th January 2018
quotequote all
As said, the noise meters at Oulton are further away from the circuit. The Donington one is much closer which is why the limit is higher.

Don`t know specifically where it is at Oulton, but I`ve always found the circuit staff to be really helpful at all circuits with drive-by. If you have a word with them before you go out, do a session then go see them, they`ll keep an eye out for you and let you know what your driveby was. Gives you a good idea if you are close to tripping it or not. smile

I did it at Donington recently and mine was only 88db on their driveby and that was using all the revs at full throttle down the start/finish straight.

SoftwareSorcerer

437 posts

249 months

Thursday 18th January 2018
quotequote all
Yazza54 said:
As I said in my opening post the test days are not on particularly convenient dates and they’re about 3x the price of a general TD.

Reading up the general consensus is that at Oulton at least, if you pass the static you should be OK. I’ll throw my new can on in the week and do a test with and without the baffle. Pretty confident about the static was just worried about the drive by with it being such a seemingly low figure, but again as I’ve researched the figures for drive by are not comparable from track to track.

Think I’ll just have to give it a crack. When I was at Oulton doing my ARDS there was a proper Audi R8 race car amongst some other tasty stuff that you could hear half way round the track and no one batted an eyelid!

Edited by Yazza54 on Sunday 14th January 21:36
As people have said, I wouldn't worry too much about the differences in drive-by for most circuits. Static tests are comparable, drive-by aren't. Have you decided where to run your first test? I'm just completing the refurb of a Contour which I'll be running in RGB this year too. Happy to meet up for a test/track day.

CrutyRammers

13,735 posts

198 months

Thursday 18th January 2018
quotequote all
Yazza54 said:
Good stuff, hopefully I’ll get on OK. Where’s their noise meter located then?
Don't know, sorry. I just short shifted anytime I was going up from 4th to 5th.

smiles1

543 posts

222 months

Thursday 18th January 2018
quotequote all
Yazza54 said:
As I said in my opening post the test days are not on particularly convenient dates and they’re about 3x the price of a general TD.

Edited by Yazza54 on Sunday 14th January 21:36
Oops missed that, sorry!

Yazza54

Original Poster:

18,493 posts

181 months

Thursday 18th January 2018
quotequote all
SoftwareSorcerer said:
Yazza54 said:
As I said in my opening post the test days are not on particularly convenient dates and they’re about 3x the price of a general TD.

Reading up the general consensus is that at Oulton at least, if you pass the static you should be OK. I’ll throw my new can on in the week and do a test with and without the baffle. Pretty confident about the static was just worried about the drive by with it being such a seemingly low figure, but again as I’ve researched the figures for drive by are not comparable from track to track.

Think I’ll just have to give it a crack. When I was at Oulton doing my ARDS there was a proper Audi R8 race car amongst some other tasty stuff that you could hear half way round the track and no one batted an eyelid!

Edited by Yazza54 on Sunday 14th January 21:36
As people have said, I wouldn't worry too much about the differences in drive-by for most circuits. Static tests are comparable, drive-by aren't. Have you decided where to run your first test? I'm just completing the refurb of a Contour which I'll be running in RGB this year too. Happy to meet up for a test/track day.
There’s one on the 10th Feb at Oulton that I’m thinking of booking. Would’ve been good to go and do Donington but the drive by limits are worrying me.

SoftwareSorcerer

437 posts

249 months

Friday 19th January 2018
quotequote all
I've run my ADR (up for sale on PH, btw) on track days at Donington many times. Absolutely no issues with noise, and it's as loud as the Contour. Can you get a static reading on your Spire?

Yazza54

Original Poster:

18,493 posts

181 months

Friday 19th January 2018
quotequote all
SoftwareSorcerer said:
I've run my ADR (up for sale on PH, btw) on track days at Donington many times. Absolutely no issues with noise, and it's as loud as the Contour. Can you get a static reading on your Spire?
Might get a chance to have a go over the weekend, waiting for a noise meter to arrive. What kind of exhaust did your ADR have? I know your contour has a large rear mounted silencer ... mines completely different with a short side exit system and 16.5 inch motorcycle can. I’ve got a few different DB killers to try but just concerns me with all the stories I’ve heard about them being so strict on noise there.

Edited by Yazza54 on Friday 19th January 15:36

SoftwareSorcerer

437 posts

249 months

Friday 19th January 2018
quotequote all
Yazza54 said:
SoftwareSorcerer said:
I've run my ADR (up for sale on PH, btw) on track days at Donington many times. Absolutely no issues with noise, and it's as loud as the Contour. Can you get a static reading on your Spire?
Might get a chance to have a go over the weekend, waiting for a noise meter to arrive. What kind of exhaust did your ADR have? I know your contour has a large rear mounted silencer ... mines completely different with a short side exist system and 16.5 inch motorcycle can. I’ve got a few different DB killers to try but just concerns me with all the stories I’ve heard about them being so strict on noise there.
Powerflow. Not a lot inside it... I do have a bung to put in the end of the exhaust - never had to use it, but it's an option for you to try something like that. If you break any noise limits, they will want you to make some sort of mechanical change to the car. Just promising to short-shift won't cut it. Best option is to do some installation laps without caning it, and have a word to see what sort of readings that's producing.


V8 FOU

2,971 posts

147 months

Monday 12th February 2018
quotequote all
Had a few problems at Goodwood with the Bentley. The side exhaust was tripping the meter by the pit wall. So an extra silencer and rear exit should do it. No probs at Brands and Castle Combe tho'

QBee

20,949 posts

144 months

Monday 12th February 2018
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I didn’t trip the drive by at Donington when my car was 105dB static. decatted 5 litre TVR V8.

And at Bedford, another MSV track like Oulton, I failed the static at 103dB despite extra bolt on cans, but was allowed on when a GT3 Porsche also registered 103.5. We both didn’t trip the drive by, which was set at 87.5 dB. So I wouldn’t be too worried about drive by tests. You can always change up before passing the meters if you are worried

JB!

5,254 posts

180 months

Wednesday 14th February 2018
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Not going to lie, I'm bricking it about failing noise at Bedford in the Honda. It has a bung in the exhaust but it is still loud...

QBee

20,949 posts

144 months

Thursday 15th February 2018
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Go get it static tested before you book. Just find a circuit near you with a track day on, call them in advance to arrange, and then rock up just after the start, after everyone has been tested. They are keen to get you on track, so tend to want to help. It’s no big deal to them to get the meter out again. All MSV circuits seem to use the same type of meter.

Bedford do their tests in the middle of nowhere on the way into the circuit, but right by a couple of small buildings. I always struggled with their test, and it is worse if it’s a damp murky morning.

Yazza54

Original Poster:

18,493 posts

181 months

Thursday 15th February 2018
quotequote all
The static test wasn’t my concern, I know the car is below 105db static.