Kit cars and noise limits
Discussion
I guess the answer to this is you can fit as big a silencer as you like, but I was wondering about kit car noise levels and in particular two things:
Are bike engined cars (tested at whatever standard the circuits tend to use) usually a problem with noise limits?
and
If you have a 'Seven type car with an externally mounted side exhaust, is it safe to assume it's just a 5 minute job to swap the silencers round? Would it be any problem getting a heavily damped silencer made up to fit?
I just wondered how easy it would be to make the typical configurations of either get through the 96dB limit at Bedford. My TVR wouldn't stand a chance (that's over 100) and I don't remember my Sylva, for example, being that much quieter.
Are bike engined cars (tested at whatever standard the circuits tend to use) usually a problem with noise limits?
and
If you have a 'Seven type car with an externally mounted side exhaust, is it safe to assume it's just a 5 minute job to swap the silencers round? Would it be any problem getting a heavily damped silencer made up to fit?
I just wondered how easy it would be to make the typical configurations of either get through the 96dB limit at Bedford. My TVR wouldn't stand a chance (that's over 100) and I don't remember my Sylva, for example, being that much quieter.
Bike engines are not necessarily any more problem than car engines, though is does vary according to engine and installation, and according to how the track undertakes sound tests. Some do static sound tests at fixed revs, some at 2/3rd maximum revs for the engine, some (most now, in fact) do continuous testing while you are on track (in which case it pays to know where the mics are located, so that you don't go past them with full open throttle).
The continuous testing tends to be linked to the Environmental Health Department of the local Council by modem, so the track gets into trouble if the don't black-flag cars that break the limits, so don't blame the track operators if you get kicked off.
Some engines that you wouldn't expect to be anything our of the ordinary are noisy by nature (eg. tuned Crossflows), and it's worth remembering that induction noise can be an appreciable part of the total - a decent air box can make a bg difference.
And, yes, it's easy enough to swap over silencers on 'Seven' type cars, though why you'd want to swap back to an illegally noisy silencer for road use is beyond me. Better to just fit a nice, big repackable silencer and keep it up to scratch (the glassfibre sound absorbing material tends to break down and blow out the back over time, so noise levels increase unless you re-pack them occasionally).
The continuous testing tends to be linked to the Environmental Health Department of the local Council by modem, so the track gets into trouble if the don't black-flag cars that break the limits, so don't blame the track operators if you get kicked off.
Some engines that you wouldn't expect to be anything our of the ordinary are noisy by nature (eg. tuned Crossflows), and it's worth remembering that induction noise can be an appreciable part of the total - a decent air box can make a bg difference.
And, yes, it's easy enough to swap over silencers on 'Seven' type cars, though why you'd want to swap back to an illegally noisy silencer for road use is beyond me. Better to just fit a nice, big repackable silencer and keep it up to scratch (the glassfibre sound absorbing material tends to break down and blow out the back over time, so noise levels increase unless you re-pack them occasionally).
I thought Bedford was 101db?
Best thing to do if you have trouble is fit a bigger (more efficient) silencer and change the induction. On a bike engine, probably the easiest and cheapest way to do this is use the standard induction that comes on the bike in the first place, and modify that if necessary. My Megabusa came with a foam sausage filter which is unfairly loud, but I have done the above with the bike induction and it has definately reduced the noise. It is just a simple swapover as and when required.
Best thing to do if you have trouble is fit a bigger (more efficient) silencer and change the induction. On a bike engine, probably the easiest and cheapest way to do this is use the standard induction that comes on the bike in the first place, and modify that if necessary. My Megabusa came with a foam sausage filter which is unfairly loud, but I have done the above with the bike induction and it has definately reduced the noise. It is just a simple swapover as and when required.
I'm afraid not - it begins with a 9 for sure at Bedford, pretty certain it's 98.
Basically the idea was: Are there any engines which can't easily be silenced to the point where they'll run at any the UK track day venues?
I was quite surprised to see my current car would fail a majority of them. It doesn't seem that loud, but apparently it's 105dB.
Basically the idea was: Are there any engines which can't easily be silenced to the point where they'll run at any the UK track day venues?
I was quite surprised to see my current car would fail a majority of them. It doesn't seem that loud, but apparently it's 105dB.
Furyblade_Lee said:
105 is the limit for Brands Hatch during the day. Think it is 101db in the evenings. I would not even attempt to take my R1 to Bedford. I think my car is around 100db.
I know, I almost fell foul of that recently when the organiser advertised the daytime limit for an evening session. Fortunately on the second attempt it miraculously registered quieter than it had done previously.Do you reckon it's fair to say it would be easier to make a car engined vehicle pass than one with a bike unit? Anything to avoid?
Chris71 said:
I guess the answer to this is you can fit as big a silencer as you like, but I was wondering about kit car noise levels and in particular two things:
Are bike engined cars (tested at whatever standard the circuits tend to use) usually a problem with noise limits?
and
If you have a 'Seven type car with an externally mounted side exhaust, is it safe to assume it's just a 5 minute job to swap the silencers round? Would it be any problem getting a heavily damped silencer made up to fit?
I just wondered how easy it would be to make the typical configurations of either get through the 96dB limit at Bedford. My TVR wouldn't stand a chance (that's over 100) and I don't remember my Sylva, for example, being that much quieter.
I really struggle with my Fury R1. At my last track day it was 108dB :-( I put a standard 2003 R1 can on (with catalyst) and it was a lot better. Induction noise is a big part of the problem so an airbox is a good move. I've repacked my titanium silencer many times and it still seems really loud. The other issuer is that bike engines are tested at quite high revs and are a lot noisier because of this.Are bike engined cars (tested at whatever standard the circuits tend to use) usually a problem with noise limits?
and
If you have a 'Seven type car with an externally mounted side exhaust, is it safe to assume it's just a 5 minute job to swap the silencers round? Would it be any problem getting a heavily damped silencer made up to fit?
I just wondered how easy it would be to make the typical configurations of either get through the 96dB limit at Bedford. My TVR wouldn't stand a chance (that's over 100) and I don't remember my Sylva, for example, being that much quieter.
Bike engines are not the best for noise!! As Rob said, a lot is induction noise and purely spinning at 12,000rpm. I have purposely not cut any holes in my bonnet and have ducted intake air to under the headlight to minimise induction noise. But i doubt may BECs will comfortably be much below 99db driveby, despite what the owners might say. Static is pretty irrelevant, as you can spin the engine at 3/4 revs on light throttle. Its when the throttles are open full that the problem occurs. BUT THAT BANSHEE WAIL IS WHY I LOVE IT!!!!!!!! I have also pained the inside of my bonnet with rubber noise reducing (apparently) paint and have rubber sealed along the edges where it joins the body to try and contain the noise. Also i have a trackday tailpipe which no longer aims out left before the nearside rear wheel, but aims downward directly into the road. Using a laser thermometer it does not seem to affect tyre temps even on track on a hot summer day. You can get a CEC to run almost silent, but no way a BEC.
Furyblade_Lee said:
BUT THAT BANSHEE WAIL IS WHY I LOVE IT!!!!!!!!
That's why I'm quite tempted by something you can easily swap the pipes over on. I know some people will frown, but I think a proper noise is all part of the fun! The Leader was great for that sort of thing. It was the best sounding 4 cylinder I've ever come across I reckon (thanks in no small part to the gloriously gutterall twin Delhortos) and the side-exit exhaust came out about 2ft below your right ear.
It's dear easy to silence a kit car on the exhaust side of things. Swapping exhausts over is an absolute doddle, and 98db is easily achievable with a big enough can, even at 7k on a bike engine.
The biggest problem you will have is induction, and more circuits are starting to clamp down on this. The standard air box on a bike engine will help massively, but good luck trying to make it fit under the bonnet
The biggest problem you will have is induction, and more circuits are starting to clamp down on this. The standard air box on a bike engine will help massively, but good luck trying to make it fit under the bonnet
You had me worried then, just booked into Bedford and its 101db
http://www.motorsportvision.co.uk/trackdays/event-...
Anyone other kits going on 25th May?
http://www.motorsportvision.co.uk/trackdays/event-...
Anyone other kits going on 25th May?
Lost my mojo said:
You had me worried then, just booked into Bedford and its 101db
http://www.motorsportvision.co.uk/trackdays/event-...
Anyone other kits going on 25th May?
I stand corrected. Maybe the 98dB limit is for evening sessions? (Or maybe I'm just plain wrong, but I could have sworn it was under 100 at some point...)http://www.motorsportvision.co.uk/trackdays/event-...
Anyone other kits going on 25th May?
Either way the point remains. Some UK track days go well into the 90s, so if you want to attend a reasonable number the car has to be capable of being restricted.
I have just failed my SVA with a road legal Remus can on my R1 MNR Vortx+, as it was a road legal can I thought it would be fine but it came out over 105 db, we put some sound proofing in the engine bay and that brought it down to 104db, it needs to be 101db
I have just fitted a silencer from a Volvo, its huge and have my retest on Friday....fingers crossed
I have just fitted a silencer from a Volvo, its huge and have my retest on Friday....fingers crossed
I can never get my head around noise testing. When i SVA'd my 'blade it came out at about 78db or something, quite ridiculous. The tester seemed more shocked than me, but he just moved on to something else.
I absolutely adore my BEC, but if my main hobby was trackday'ing then i would get a CEC so i could drive EVERY circuit i wished, noise testing at circuits is a complete random hit-and-miss affair.
I absolutely adore my BEC, but if my main hobby was trackday'ing then i would get a CEC so i could drive EVERY circuit i wished, noise testing at circuits is a complete random hit-and-miss affair.
No mate, i live on the Kent / Surrey border and i meet at Bletchingley, Jct6 M25 and there is a new one being set up near Maidstone. If you can get along to one of those i will take you for a spin, but i warn you, you will want one!!
I *MAY* be considering selling mine later in the year, I really fancy building one of those new Sylva Spectre, I am just waiting to see one finished in the flesh to decide. But I would want it PURE 1960's, in Almond Green, so a bike engine would be a no-no. But then i would miss the mentalism of the R1, so....... i am a troubled boy!
I *MAY* be considering selling mine later in the year, I really fancy building one of those new Sylva Spectre, I am just waiting to see one finished in the flesh to decide. But I would want it PURE 1960's, in Almond Green, so a bike engine would be a no-no. But then i would miss the mentalism of the R1, so....... i am a troubled boy!
My Tiger has no air box on the induction yet passed the noise test at Bedford.
Actually to be precise...
It failed then passed after wasting half the day driving up to Grand Prix Racewear in Silverstone and repacking my exhaust in their car park.
Nice of GPR to lend me the tools to do the job!
Actually to be precise...
It failed then passed after wasting half the day driving up to Grand Prix Racewear in Silverstone and repacking my exhaust in their car park.
Nice of GPR to lend me the tools to do the job!
as some former postings stated: noise often comes from induction. even the biggest side-can will not reduce the noise under certain levels when you have 2 weber sidedraught carbs with open trumpets.
also remember: the bigger the side can, the better fixing you need...and a flex-pipe between ex-manifold and can, otherwise the manifold will crack sooner or later.
you are all lucky living in UK...here in germany the noise levels for e.g. a kit registrated 1991 (whatever engine is fitted) must pass 83db in a driving cycle, which means around 87db with 2/3 of rpm.
you are maybe wondering why some of the actual kits do have a rear exhaust?
EU-laws, IVA, posiibilities for the kit-manufacturer to sell these cars also outside uk are the reasons.
also remember: the bigger the side can, the better fixing you need...and a flex-pipe between ex-manifold and can, otherwise the manifold will crack sooner or later.
you are all lucky living in UK...here in germany the noise levels for e.g. a kit registrated 1991 (whatever engine is fitted) must pass 83db in a driving cycle, which means around 87db with 2/3 of rpm.
you are maybe wondering why some of the actual kits do have a rear exhaust?
EU-laws, IVA, posiibilities for the kit-manufacturer to sell these cars also outside uk are the reasons.
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