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Exhaust Tips And How Do They Effect Sound Level?


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#16 nicklouse

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Posted 16 June 2021 - 12:40 PM

 

 

Overall, the tip has very little to do with the sound/noise. However, each will have an attribute. It also depends on what 'noise' you're trying to reduce. If an overall reduction, rather than targetting a certain set of frequencies (usually higher ones cause increased dB), use a double skinned tip.

Now here is another thought for your perusal.
 
let’s say you have two silencers of the same cross section but one is twice the length of the other.
 
would they dampen different frequencies?
 
both are 4x8 and one is 8” the other 16” long will have about a 1” gap between them.
 
the 16 first then the 8.

Absorptive or reactive silencers ?

https://www.acoustic...5/papers/34.pdf

 

Both are absorptive type.



#17 bluedragon

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Posted 16 June 2021 - 11:54 PM

Generally speaking, all other factors (like design/type) being equal, a larger silencer will have a greater noise reduction effect. More volume means more silencing. Unless there's some odd shaping difference, different internal construction, or a difference in the materials used (i.e. stainless steel vs. mild steel) there likely will be no frequency differences in dampening - just more effectiveness across the spectrum.

 

 

Dave



#18 nicklouse

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Posted 17 June 2021 - 09:19 AM

Generally speaking, all other factors (like design/type) being equal, a larger silencer will have a greater noise reduction effect. More volume means more silencing. Unless there's some odd shaping difference, different internal construction, or a difference in the materials used (i.e. stainless steel vs. mild steel) there likely will be no frequency differences in dampening - just more effectiveness across the spectrum.

 

 

Dave

If I read this correctly if the volume of the two is the same as the volume of a single (cross-section and construction the same) there should be no difference in the noise reduction? 



#19 bluedragon

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Posted 17 June 2021 - 09:59 AM

In theory, but it's hard to say that "all other things are equal" with adding the volume two separate mufflers vs. one large one. I would guess that the single large silencer would be somewhat more effective, but not magnitudes better.

 

With space being an issue on almost all cars, using multiple silencers is absolutely a valid approach to reducing sound levels while trying to maintain good flow. (of course, the best way to silence an exhaust is to restrict the flow...)

 

Now, if one is concerned about certain frequencies, using silencers of different types (not just sizes) could help that. That is also the purpose for which resonators were made - resonators don't do a great deal in terms of reducing overall sound output, but they are tuned to quiet certain frequencies. This can help a smaller volume silencer achieve effective muffling, by diminishing some unpleasant frequencies. They can make the sound less objectionable even if the overall db effect is not that great.

 

Dave



#20 KTS

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Posted 17 June 2021 - 12:47 PM

my reading of the paper above suggests the physical dimensions of the the silencer will effect the transmission losses (..or potential gains !) of particular frequencies as they pass through it, as "maximum transmission losses occur at odd multiples of a quarter wavelength", so despite both silencers being of the same volume, and potentially reducing noise levels by comparative amounts, i would expect each to sound different.



#21 splintercat

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Posted 19 June 2021 - 07:30 AM

1275 mpi,
Fast road head,
Stainless maniflow lcb,
Stainless twin box rc40,
Play mini tail pipe welded on,

Low deep bass sound,
:-)

 

the louder the better I say....long live the cherry bomb, however only replying because like the little piece of bling/alloy that you have added just above the exhaust.......sweet.



#22 Tones61

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Posted 20 June 2021 - 12:16 PM


:-)
 
the louder the better I say....long live the cherry bomb, however only replying because like the little piece of bling/alloy that you have added just above the exhaust.......sweet.
[/quote][/quote]


Hi splintercat,
Thanks dude,yes it's a bit of alloy plate I cut out,
It's a looka likey / real heat shield :-)




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