HappyFather
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| posted on 4/6/10 at 12:05 AM |
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Regulations on noise and is 76dbA crazy?
Hello,
I'm waiting for my kit and I've been investigating the possibility to get it road-legal in Portugal.
After many law-reading, I get to the fact that noise tests are done according to UNECE Regulations 51 and 59 with a dbA limit of 76, based on what my
car will be (Aries Locoblade - carbed Fireblade).
Looking at UK's IVA guide, it seems that noise tests aren't done according to UNECE Regulations 51 and 59, although the methodology for
the test looks very similar to the methodology for the UNECE stationary test. But IVA allows for 99dbA...
What I'm wondering is if there is just a different limit with the same procedure or if the procedure is slightly different (and I failed to
catch that difference). And if it's different to a point where it might be possible to have a reading bellow 76dbA with the Fireblade engine.
Otherwise, I'll definitly have to ship the car to the UK when ready and do the IVA there...
Thanks for reading!
HappyFather
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norfolkluego
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| posted on 4/6/10 at 12:16 AM |
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Simple answer, yes it's crazy, don't see how you could build any car to that db level, same kind of level as a vacuum cleaner
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adithorp
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| posted on 4/6/10 at 06:41 AM |
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What revs is that done at?
IVA noise test is done at either 75% max power revs, or 66% max revs. You'd find it VERY difficult to get through 76db at those revs but if it
was at idle then it might be possible.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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BenB
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| posted on 4/6/10 at 07:33 AM |
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It would be interesting to see how many manafacturer cars would pass that test!
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sebastiaan
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| posted on 4/6/10 at 07:41 AM |
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quote:
Originally posted by BenB
It would be interesting to see how many manafacturer cars would pass that test!
All of them, as it's in the type approval....
It basically is a full-throttle drive-by test at 7,5 or 10 metres distance, measured once at the left hand side of the vehicle and once on the right
hand side. Values are averaged over a 2nd gear run and e 3rd gear run. Speed at the start of the driveby is normally 50km/h. See
http://www.unece.org/trans/main/wp29/wp29regs41-60.html for more information.
With a BEC, you'll be screwed I guess..... 
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ashg
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| posted on 4/6/10 at 08:01 AM |
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nice... drive by equals the doppler effect. you may be ok if they dont take the reading exactly as the car passes the meters as te freq will be
changing
[Edited on 4/6/10 by ashg]
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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sebastiaan
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| posted on 4/6/10 at 08:10 AM |
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It's the maximum value during the driveby....
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HappyFather
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| posted on 4/6/10 at 08:47 AM |
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But actually, the UNECE Regulation defines 2 tests.
1) the above mentioned drive by, that based on some car specifics (power, # of gears) can be done only in 3rd gear and get the 76dbA limit instead of
the regular 74dbA limit
2) a stand still test, where noise is measured with the car rev'ing at 3/4 of the revs at which the engine outputs it's top power. On this
test, the limit is also 74dbA
The 2nd test is the one that seems to me like the one done on IVA. I would like someone to tell me if the 2nd UNECE test is in everything equal to the
IVA one or if it has differences that may render comparing dbA limits useless. And give me a glimpse of hope that with a nice airbox and restrictive
silencer, it could be archieved.
Thanks again for all the replies!
HappyFather
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Fozzie
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| posted on 4/6/10 at 08:59 AM |
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HappyFather,
We do have another builder on here from Lisbon, Portugal, his user name is:
JoaoCaldeira
I think he is building an MNR....
Might be worth a u2u/email to him to see if he has any thoughts or insight to your query/problem ?
HTH
Fozzie 
'Racing is Life!...anything before or after is just waiting'....Steve McQueen
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BenB
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| posted on 4/6/10 at 12:27 PM |
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quote:
Originally posted by Fozzie
HappyFather,
We do have another builder on here from Lisbon, Portugal, his user name is:
JoaoCaldeira
I think he is building an MNR....
Might be worth a u2u/email to him to see if he has any thoughts or insight to your query/problem ?
HTH
Fozzie
I think he was planning on building it here then importing it after SVA. I seem to recall he's built it.... but I may be wrong. He occasionally
pops up on the googlegroups BEC list.
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Fozzie
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| posted on 4/6/10 at 01:28 PM |
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Ben, you could be right there, I just looked at his profile, and his is built, a bec too (R1)..he was last active on here on 31st May..... ah
well....
Fozzie
'Racing is Life!...anything before or after is just waiting'....Steve McQueen
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stevebubs
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| posted on 4/6/10 at 01:58 PM |
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quote:
Originally posted by Fozzie
Ben, you could be right there, I just looked at his profile, and his is built, a bec too (R1)..he was last active on here on 31st May..... ah
well....
Fozzie
I'm sure he'll be around...before building the MNR, he was looking at various options so I expect he'll be able to offer some sound
advice...even if it culminates in "ship it to the UK for testing"
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HappyFather
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| posted on 4/6/10 at 03:11 PM |
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I've been swapping mails with Joćo on the Portuguese locost yahoogroup. He wrote this morning that 76 might be doable since bikes can do it. But
it's just speculation.
That is why I was trying to figure out if the UK and PT tests are slightly different (to a point where the difference mattered) or if anyone had done
a silenced seven. Until now 86dbA is the lowest someone posted.
On a side note, Joćo built is MNR R1 in PT, shipped it to UK for SVA and it was driven back to PT. At the time, SVA in PT was even more obscure than
now. In March we got the 2007/46/CE finally transported to local regulations and it might be possible now. This why I only ordered my kit when I was
sure I could IVA it in the UK too.
Thank you all for the answers up to now!
HappyFather
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smart51
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| posted on 4/6/10 at 03:39 PM |
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My Suzuki Cappuccino with a stock exhaust measured 87 dB at a track day. That was the quietest car of the day according to the marshal. You
won't get a bike engine that quiet. I'm guessing the test must be at idle.
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t.j.
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| posted on 4/6/10 at 05:51 PM |
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quote:
Originally posted by HappyFather
But actually, the UNECE Regulation defines 2 tests.
1) the above mentioned drive by, that based on some car specifics (power, # of gears) can be done only in 3rd gear and get the 76dbA limit instead of
the regular 74dbA limit
2) a stand still test, where noise is measured with the car rev'ing at 3/4 of the revs at which the engine outputs it's top power. On this
test, the limit is also 74dbA
No the second test is only to measure the dBA value which is ment for the police or MOT afterwards.
So first drive-by, then 3/4 Pmax. This value will be stated in approval.
The UK IVA-basic has the "luck" to be measured stationary 99 dBA at 3/4 Pmax.
In NL you have to drive-by, you will get +2dBA for "free" and 1 in the measurement. So as the limit is 74, your maximum is 74+2+1= 77 dBA
with full opened trottle at 50 km/h!
So is it possible for us home-brew-cars?
Please feel free to correct my bad English, i'm still learning. Your Dutch is awfull! :-)
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smart51
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| posted on 4/6/10 at 06:08 PM |
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How far is the drive by distance from car to microphone? You can add 6dB (I think) to the exhaust noise every time you double the distance to the
microphone. 8m instead of 0.6m brings your 77dB to 101 dB.
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