Forum Home / Ask the Experts! / Noise Testing

10/03/2006 09:22:58
SteveChilds
I've got myself a Noise meter now, what is the standard practice for measuring the sound of the exhaust? i.e. how far away from the exhaust and at what RPM?
10/03/2006 11:59:52
Ralph
[URL="http://pitlane.mgs-on-track.com/showthread.php?t=63"]Noise regs[/URL] RTFM ROFL BTW The V5C now includes a section for noise level on new cars. My TF160 shows 95dB static and 74dB drive-by.
10/03/2006 12:03:12
SteveChilds
[quote=Ralph][URL="http://pitlane.mgs-on-track.com/showthread.php?t=63"]Noise regs[/URL] RTFM ROFL BTW The V5C now includes a section for noise level on new cars. My TF160 shows 95dB static and 74dB drive-by.[/quote] Yeah, I saw that but didn't know if the method used by Silverstone was any different... Of course the fact I forgot to say it was with Silverstone kinda didn't help!! lol
10/03/2006 13:28:40
SteveChilds
[quote=SteveChilds]Yeah, I saw that but didn't know if the method used by Silverstone was any different... Of course the fact I forgot to say it was with Silverstone kinda didn't help!! lol[/quote] Anyway, went out in the rain and measured it - 99.6 dB
10/03/2006 13:53:43
Dave
Steve, Often they quote a distance and angle at a certain revs - typically, 50cms at 45 degrees from tailpipe at three quarters of max revs. Silverstone don't do a static test and the limit is 105db so you are well within that!
10/03/2006 16:56:54
Steve White
[QUOTE=SteveChilds]I've got myself a Noise meter now, what is the standard practice for measuring the sound of the exhaust? i.e. how far away from the exhaust and at what RPM?[/QUOTE] Take it you shop at Maplins too ;) TBO I dont think you will have a problem passing the noise test, its only really when you have MTB's that you start encountering problems as the induction noise can send it over the limit, especially on cold days. These are is the very reasons I also got a sound meter recently :rolleyes: Not had chance to measure the TT extreme yet but suspect it will be a lot closer to 105db than yours, posably even over it:o
05/04/2010 13:01:35
Martin P
Hi, I am preparing my MGB V8 roadster for a little track action but was concerned about the noise regs as I have a completely open exhaust system. I had my car tested at 3,800 revs at 0.5m and 45 degrees away. My max power is at 5,500rpm. The measurement was a surprising 101db which was quieter than I expected. However, to get it down further if needed, I had inserts made for the tailpipes as I didn't want to get a new exhaust system. I thought I'd share it with everyone as it may be a quick and easy solution for some people worried about noise limits. I've not had it tested again, but the exhaust note has changed and it seems a fair bit quieter. I'll let you know when I get it tested again, what it turns out to be. Hope the photos come out o.k. Martin
05/04/2010 19:25:48
Martin C
Hi Martin, That looks like a very neat piece of kit, also should you still be marginal it looks like it would be easy to put some steel wool in between a couple of baffles. Also because of the neat design it would be securly held in as well. But please bear in mind, when having a noise test at a circuit it will pass or fail on the reading they get from their meter on the day. I know it can cause some problems at times when people have had independant tests, but failed at a circuit. I've never known anybody successfully argue it passes elsewhere at such and such decibels either. It is also worth using the ease up to the required revs hold steady and ease gently down again. Bliping up to the revs and lifting straight off can cause spikes in the reading which can also lead to failures. Look forward to seeing what looks like a very tasty V8 out with us soon. :D
06/04/2010 05:35:10
Tim Guy
Yes, a nice piece of kit. Bear in mind that most tests are based on 3/4 red line revs and that increasingly drive by noise testing equipment is being used.
16/04/2010 17:18:39
Martin P
Just to close the story, I had my car retested with the inserts in and I got between 96db and 98db. The two sides were slightly different but that was probably due to my right foot. Still, this is good enough for pretty much all tracks. Just to be 100% I can always add some wadding to the last baffle to get it down even further as Martin C pointed out. It was also tested with the car backing onto a building only 10ft away so that will add a little to the reading. An interesting side affect of adding the baffles was a noticeable increase in throttle response. That little bit more back pressure obviously had a beneficial effect. So they are staying in now all the time. Unless I want to be particularly noisey that is.:D
16/04/2010 20:59:58
Martin C
Hi Martin, Here's the groan factor, sounds good, no pun intended..............honest:D Look forward to meeting you at Brands next month:)
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