Muffler sizes vs noise reduction (1 Viewer)

[slambson]

I've settled on either a 6" diameter or 5" X 8" magnaflow muffler for my turbocharged 3FE. The issue is I have a variety of selections in both for lengths. I'm assuming the 6" round or 5 X 8" muffler will have similar noise reduction qualitys. Is that a fair assumption? Lastly how much difference does length make in reduction?

 

[slambson]

The 5 X 8" variety run in 14", 18" and 24" lengths and the 6" variety run in 14" and 18" varieties.

 

[sc40]

so the bigger the more quiet?

 

[Walking Eagle]

I think the longer it is the more deadening - but have no facts to back it up - try looking at their web site.

Yep, the manufactures web site is always a good bet

http://www.magnaflow.com/07techtips/faq/question03.asp

MagnaFlow's Frequently Asked Questions

Question: What sound difference will I get with a smaller muffler as opposed to a larger muffler?


Answer: A smaller muffler is going to give you a much louder sound than you would normally get with a larger muffler. The larger or longer the muffler, the less sound you will get. The smaller or shorter the muffler, the more sound you will get.

 

[slambson]

I guess I was hoping for something a bit more empirical. I've seen the FAQ but the statement doesn't give much for how much quieter/louder a particular muffler might be. A 5X8 would have 31.4 cu in and a 6" would have 28.47 cu in of area (calculating the gross area). Theoretically the 5X8 has 10% more area but with the one side being closer to the perforated tube the effect may be negligable. If going from an 18" to a 24" muffler gets you a 1dB decrease but costs $30 more than I would not find it worthwile to spend the extra money (theoretical).

I need Idaho Doug to chime in here. Didn't he work on vehicle designs in a past life?

 

[IBCRUSN]

Size of the muffler plays a part but is not necessarily the whole enchalada. When my exhaust was replaced shortly after I purchased it I stuck with an oval muffler roughly the same size as OEM. I did omit the resonator. Overall it sounds ok not loud but because of the pipe lengths and no resonator it does have the 2000 rpm drone. The resonate frequency of an exhaust system is the relation between pipe length and diameter, essentially the volume of the system. Since I am planning on replacing my current system I'll post the links I find that explain what we're all getting at.