Discussion
In my limited experience it is dB(A) and measured at 4500rpm at 0.5m from the tailpipe, as detailed below:
Blue Book said:
“12.17.8. Sound Test Requirements. Measurements will be made at 0.5m from the end of the exhaust pipe with the microphone at an angle of 45° with the exhaust outlet and at a height of 0.5 to 1.0m above the ground. Where more than one exhaust outlet is present, the test will be repeated for each exhaust and the highest reading will be used. In circumstances where the exhaust outlet is not immediately accessible, the test may be conducted at 2.0m from the centre line of the vehicle at 90° to the centre line of the vehicle, with the microphone 1.2m above the ground. Measurements should be made outdoors with no large reflecting objects (e.g. walls etc.) within 3.0m (in the 0.5m test) or within 10.0m (in the 2.0m test). Background sound
levels should be at least 10dB(A) below the measured level.
Where possible measurements should be taken as close as possible to the vehicle, at the defined distances, to avoid background noise. Cars of periods A to D falling within Sections C and D should run engines at two thirds maximum RPM. The 2.0m test can be made from either side of the car. The highest reading registered being the one needing to comply with the maximum noise requirements.”
levels should be at least 10dB(A) below the measured level.
Where possible measurements should be taken as close as possible to the vehicle, at the defined distances, to avoid background noise. Cars of periods A to D falling within Sections C and D should run engines at two thirds maximum RPM. The 2.0m test can be made from either side of the car. The highest reading registered being the one needing to comply with the maximum noise requirements.”
AngryS3Owner said:
Well I didn't see the post when we were taking a look, but Ed it might not be that bad. I didn't see your point about it being A-weighted and the readings of 99 at idle and around 108-110 at 2/3 was with c-weighting. Give us a shout if you want me to pop by again, however I still think it'll be too loud.
Ben you've lost me ! (bit like the M4 jsut now... oops sorry!)Well there's two frequency ranges that the meters can be weighted to measure, I didn't remember your post until just after you'd driven off (I had a look) but I'm taking a stab it should have been A-Weighted not C-Weighted as it was set when we had a go.
This page explains some of it, it *might* make a differnce for the better or worse.
This page explains some of it, it *might* make a differnce for the better or worse.
AngryS3Owner said:
Well there's two frequency ranges that the meters can be weighted to measure, I didn't remember your post until just after you'd driven off (I had a look) but I'm taking a stab it should have been A-Weighted not C-Weighted as it was set when we had a go.
This page explains some of it, it *might* make a differnce for the better or worse.
well we should probably have a 2nd blast then ?!This page explains some of it, it *might* make a differnce for the better or worse.
Spoke to helpful fella at Thruxton & it sounds like a no no. However the limit at Castle Combe in 100db so this might be possible with something like this :
http://www.merlinmotorsport.co.uk/EXHAUSTS-Merlin-...
They're are in the circuit which is handy.. can test the noise etc.
A pal has previously made mutes for his vintage bikes.. gonna have a chat to him also
http://www.merlinmotorsport.co.uk/EXHAUSTS-Merlin-...
They're are in the circuit which is handy.. can test the noise etc.
A pal has previously made mutes for his vintage bikes.. gonna have a chat to him also
EdT said:
Spoke to helpful fella at Thruxton & it sounds like a no no. However the limit at Castle Combe in 100db so this might be possible with something like this :
http://www.merlinmotorsport.co.uk/EXHAUSTS-Merlin-...
They're are in the circuit which is handy.. can test the noise etc.
A pal has previously made mutes for his vintage bikes.. gonna have a chat to him also
I got down to Castle Combe with a set of internal silencers for the Chim:http://www.merlinmotorsport.co.uk/EXHAUSTS-Merlin-...
They're are in the circuit which is handy.. can test the noise etc.
A pal has previously made mutes for his vintage bikes.. gonna have a chat to him also
They tested me at teh track as follows:
Without Internals 107db
With Internals 104db
With internals plus Merlin outer cans (bought on the day!) 97db
I do have the Cherry Bomb conversion which adds to the noise a little
Bingo
I think they cost about £110 for the pair.
EdT said:
what are the internals you mention.. main baffles?
No, just shove 'em down the exhaust pipes, which should be the same as your Griff?Where are you based, you can pop round and have a go - i am just round the corner from Ben's house, so if you speak nicely to him, you could get a definite read with the various conbinations of silencers.
HTH
E1DJH said:
EdT said:
what are the internals you mention.. main baffles?
No, just shove 'em down the exhaust pipes, which should be the same as your Griff?Where are you based, you can pop round and have a go - i am just round the corner from Ben's house, so if you speak nicely to him, you could get a definite read with the various conbinations of silencers.
HTH
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