rodgling
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| posted on 28/1/16 at 04:42 PM |
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quote:
Originally posted by Fcck2000
We fit one of these when we have to on track days, brings static down by about 5dbls.
That's a good reduction - what's inside it? Is it baffled?
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Fcck2000
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| posted on 28/1/16 at 05:14 PM |
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I can't remember exactly. I seem to remember it had a perforated smaller section inside which adjusted the direction of the gasses towards the
outer packed area. It definitely works. We tested with our phone dbs sensor before and after and it gave 4/5 dbs reduction.
The guys at Custom Chrome were really helpful, we failed the noise test at Mallory and gave them a call in the morning (9am) to see what they could do
for us at short notice. We gave them our exhaust sizes over the phone and collected it at 11am, it was still hot from the welding. Went back to
Mallory and passed the noise test after we also baffled the intake with some welding mat which Custom Chrome also donated to us.
Tiger SSC
220bhp on standard MZR Duratec engine with throttle bodies and mild camshaft upgrade.
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The Black Flash
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| posted on 2/3/16 at 11:00 PM |
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quote:
Originally posted by rodgling
quote:
Originally posted by The Black Flash
I would, trouble is, I need 2 :-/
I'll have to do something come the new year though.
I'm going to do Snetterton in a few weeks, will do noise test with and without one of these fitted and let you know how much improvement I get.
Soooo, did you find anything out?
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rodgling
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| posted on 2/3/16 at 11:05 PM |
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quote:
Originally posted by The Black Flash
quote:
Originally posted by rodgling
quote:
Originally posted by The Black Flash
I would, trouble is, I need 2 :-/
I'll have to do something come the new year though.
I'm going to do Snetterton in a few weeks, will do noise test with and without one of these fitted and let you know how much improvement I get.
Soooo, did you find anything out?
Unfortunately not - the version I ordered turned out to be slightly too small to fit, so I had to bodge it again with a bung made of scouring pads. I
have the right size now but unlikely to get another trackday until the summer. I'll try to report back how I get on.
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The Black Flash
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| posted on 16/4/16 at 05:18 PM |
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Soooo, having booked in at Croft for the 20th, I took the plunge and bought a pair of decibel devils.
Tested with my home noise meter at 50cm, 45 degrees from one of the outlets:
Without Decibel Devil:
104.0
106.1 (!)
104.5
With Decibel Devil
101.2
101.2
102.3
I think that the 106 was an outlier as I blipped it a bit. Anyway, looks like a solid ~3db reduction there.
It's also clear that wrapping the headers has made the thing much noisier, it was 102 last year before I wrapped it. I will see how it goes on
track this time and perhaps remove the wraps if I think I can get away with it.
In the interest of science, I also tried it with a large metal disk 1" in front of the outlet - I thought that this might reduce the sound waves
going outwards. Results were interesting:
With Disk:
104.2
101.7
102.1
Seemed to make things worse. I then tried moving the sound meter so that it was head on to the exhaust pipe, rather than at 45 degrees. Only two
readings as I didn't want to annoy the neighbours more than I already had!
With decibel devil, head on, no disk: 101.3
With decibel devil, head on, with disk: 100.00
So, the disk *may* improve the situation directly behind the exhaust, but not at an angle, in fact may make it worse. I was interested that the
reading without the disk was the same head on and at 45 degrees.
I've had to modify them a little to increase the length of the straps, to fit into my curved exhaust - just welded on an extension. Other than
that, they seem to do the job. Hopefully that's useful to some.
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rodgling
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| posted on 16/4/16 at 05:56 PM |
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Thanks, that is good to know. My current plan is to make up a baffle from a rod and some semi-circles welded on like so (side view):
___|___ ____
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which I can shove up my straight-through exhaust, as an additional option to the Decibel Devil. Will see how that works out.
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The Black Flash
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| posted on 29/4/16 at 08:23 PM |
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I've also since found that all of the wadding had gone from one of the silencers, and half of it from the other. I'm going to blame the
fact that I wrapped the headers making the silencers get too hot.
Repacking them with acousta-fil so hopefully shouldn't have problems in future.
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rodgling
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| posted on 16/7/16 at 08:27 AM |
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I tried the DD at Snetterton recently. I just about scraped through once I'd stuffed it full of scouring pads, but I think they were being
generous because I'd made the effort to fit a bung.
So, go big or go home - I got this made:
which attaches to the side can and runs under the suspension to sit under the fuel tank. It's removable for road use, hopefully the limited
ground clearance (about 70 mm) will be OK on track.
Static noise has dropped from about 102 dB at 4500 rpm down to around 95 dB, very happy with that.
[Edited on 16/7/16 by rodgling]
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