Another Exhaust Thread :)

[Rotary#10]

Originally Posted by RETed

Nah, not really...

I'll put money that a perforated tube muffler will outflow any chambered muffler when it comes to performance, period.

Sure, the chambered muffler will minimize noise - that's it's primary design criteria.

I'm arguing performance versus noise suppression.

There's two ways to suppress noise from the exhaust - choke the crap out of it or "tune" by resonance.
Resonance tuning is a lost art, and does exactly what NoDOHC mentions above.
The problem is that you cannot tune the entire RPM band out - you can only quiet RPM ranges, which can sometimes be quite narrow.
So unless you find an experienced exhaust guy that knows the car's set-up, it becomes an expensive proposition of experiementing with muffler positions to get what you want.

I always say to just stuff the biggest, honkin' muffler you can affort and fit under the car to get the best suppression.


-Ted

Hey could you give me more information about this tune by resonance? its sound interesting. please?

[vex]

Originally Posted by Rotary#10

Hey could you give me more information about this tune by resonance? its sound interesting. please?

It's pretty straight forward. You tune your exhaust by the frequency of the RPM band. For instance you can tune it by Exhaust length, mufflers--both in dimensions, and number, as well as configuration.

This kind resonance is for all intents and purposes deconstruction wave interference. If you're only using pipes you get the phenomenon only at modes of certain frequencies; ie 2000, 4000, 8000 rpm. When you begin adding in mufflers, pre-silencers/resonators, you begin to affect the wave pattern throughout the exhaust system. Now since we can't have a modifying length of the exhaust to minimize the entire rpm band you make compromises. You can have the exhaust be relatively quiet below say 3000RPM then it can get progressively louder before hitting another node and becoming quiet again.

At the end of the day one can utilize Fourier transforms to locate and eventually eliminate the peak 'oscillation' or waves and all harmonics there of. I would attempt to tune my exhaust using this method but it may just be an attempt in futility because I'm lacking the time to do it.