ahahhahaha

 

[QUOTE]Originally posted by MeTh222
[B]I have the magnaflow single muffler (not sure of the model #).

 

I think it was on this board that I heard Ferraris have dual pitched exhaust notes. That's why they sound cool.
Could we get some(or one) tunable supertraps and tune them differently to give us the same effect?

I do not have a degree in physics, and I did not stay in a Holiday Inn Express last night (drjekyll2000), so I am not necissarily saying it will work. I am just asking really.

Thanks...Incubus

 

No, it can't be "altered" per se, just as a graphic equalizer can't alter the pitch of a piece of music. Rather, a g.e. suppresses (filters) certain pitches relative to others. So, what's theoretically possible for an exhaust is to filter out any pitches lower than the "fundamental" pitches corresponding to, say, 9000 rpm, which would leave only the "harmonics" (the frequency multiples of the fundamental pitches). But in practice this would be SO restrictive in terms of performance that it would be like stuffing an orange up the tailpipe.

boltonblue is correct in saying that the exhaust can be also viewed as a transmission line (t-line). This perspective is useful when tuning the exhaust for net power delivery, and it's the basis for David Vizard's oft-quoted "No-Loss Exhaust" article in Circle Track magazine. The t-line perspective is not helpful from an "acoustic quality" perspective, though (except that you can bet a "no-loss" exhaust design will be loud ).

 

[QUOTE]Originally posted by Incubus
[B]I think it was on this board that I heard Ferraris have dual pitched exhaust notes.

 

[QUOTE]Originally posted by SteveUCI
[B]I believe that's the "resonator".

 

It is a Helmholtz Resonator. Known as an effective way to add damping to a standing wave (mode) or absorb energy at an undesirable disturbance frequency in an acoustic medium. The Resonators are commonly used for tuning of acoustic systems such as industrial processes, engine intake and exhaust, mufflers in ducts and pipes, listening and recording rooms and more. A Helmholtz resonator is comprised of a cavity connected to the acoustic system of interest, e.g., a duct, via one or a few narrow tubes through which the fluid travels back and forth between the cavity and the external medium.

 

Here's a few tid bits I've picked up on our system:

The hand-assembled exhaust header is stainless steel with a 4 into 2 into 1 into dual exhausts design. The headers reportedly weigh about 22 pounds. The exhaust is tuned to produce a 42% reduction in back pressure.

The gorgeous exhaust note was painstakingly orchestrated to approximate the blood-curdling whine and roar of a Formula 1 engine.

After-market vendor Comptech in Calif said the originals were so good they went through 14 header prototypes to get one that made better power across the range.

Some things to consider if you want to go to a louder after market exhaust system:
Noise induced hearing loss is dependent upon: sound level measured in dB, spectral distribution-sound energy vs. frequency, and duration of noise. Permissable levels and durations are: 90dBA-8hrs/day, 92dBA-6hrs/day,95dBA-4hrs, 97-3hrs, 100-2hrs, 105-1hr, 110-1/2 hr, 115 1/4 hr. For short exposure of about 80 dbA for 8 hrs you may experience a temporary hearing loss but with continued exposure this will become permanent with the shift starting at about 3-6KHz. Sound level meters are rated in dBA because low freq. are weighted differently than high freq. in steady state noise due to the more dramatic effect on the highs. Examples of noise: Conversation-55 dB, Rush Hour traffic -80 dB, Truck/lawnmower-100dB, jet airplane-120 dB, shotgun-140dB. Impulse noises such as guns, should not exceed 140db. Levels above this can cause pain. Cold weather or cool air blowing on your ear will not cause hearing loss, however if you get a head cold, ear infection, swimmers ear, or eustation tube dysfunction (in airplanes or on mountain tops) these could temporarily effect your hearing.