StreetStangs.net - Quarter wave tubes

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- - Quarter wave tubes (http://www.streetstangs.net/showthread.php?t=11769)

Quote:

Originally Posted by Purple1995Pony (Post 173743)

This is how the mufflers are setup OE on SN95's ( and Foxs too I think)for that reason. Most aftermarket H or X pipes don't stagger the connections so ...dronnnnnnne. Check out a stock H pipe to see.

The H pipe has nothing to do with it for a number of reasons.

High frequencies have short wave lengths, low frequencies have long wave lengths.134Hz is 100.7756" even at room temperature. 134Hz is pretty long and wide. It's probable that the muffler is already in the 134Hz range. Moving it a few inches isn't going to get it out of or into the 134Hz range. If the muffler is completely in the wrong spot there isn't enough room to move it into the right spot. Further, even if I could put the muffler in exactly the right spot, The muffler DOESN'T have tuning for the 134 Hz frequency. I could put the muffler anywhere, and it still wouldn't attenuate the 134Hz frequency.

Assuming the stock mufflers did not drone, I doubt it had anything to do with where they were and far more to do with what they were.

I don't think IMHO, frequency has much to do with a matched set of mufflers. If the sound is not in sync between the 2 the (sound or frequency if you will, gets to the mufflers at different times) drone "seems" to disappear. A split second difference will change the sound even if it's very little.

Fundamental Frequency is 134 Hz. C = 380 m/s. Lambda is 111". Quarter wave is 27.75" An inch here or there is meaningless.

It's like walking across Iowa. You go a long way, but there isn't much of an elevation change.

Quote:

It's like walking across Iowa...

:lol: Boy is that the truth.

The unequal length of the H-pipe is recovered with one short and one long flowtube. The mufflers on every mustang I've seen have been side-by-side (unless it was hacked up at a muffler shop).

The drone has to do with the length of pipe...different lengths give you different eigenfrequencies, which can be amplified or diminished by mufflers (think Flowmaster or Super Turbo). The heimholtz chambers can change the frequency where the thing drones...or cancel out certain frequencies.

Quote:

Originally Posted by coupe (Post 173804)

(think Flowmaster or Super Turbo).

Ya, think really crappy helmholtz resonators. :)

Assuming the stock exhaust system didn't drone, do you know how FoMoCo did it?

The optimist in me wants to believe that they had some trick resonator in the muffler. The cynic in me thinks they just had some highly restrictive design that pulled all the energy out.

Lots of good stuff here in -
http://naca.central.cranfield.ac.uk/...eport-1192.pdf