Another Exhaust Thread :)

[RETed]

Chambered mufflers are a waste of time if you're looking for performance.


-Ted

[vex]

Originally Posted by RETed

Chambered mufflers are a waste of time if you're looking for performance.


-Ted

In my case performance has to take a back seat to daily ability/what won't get me in trouble with LEO's.

I still aim to have around 400HP with my setup, but I would like it to be as quiet if not quieter than stock (I know I'm asking for the impossible)

[RETed]

Originally Posted by vex

I still aim to have around 400HP with my setup, but I would like it to be as quiet if not quieter than stock (I know I'm asking for the impossible)

Not going to be possible, unless we're talking about something super complicated which implies super expensive...

Ever seen a Ferrari exhaust?
It's basically one big muffler from engine to tailpipe!

Chambered mufflers choke off too much performance - you'd need to build a 600hp engine to get 400hp after choking it off with all the chambered mufflers.

You want quiet?
Just don't rev over 2,000RPM.
You thinking you can rev up to redline past law enforcement?
I doubt stock is going to prevent you from getting looks.

You own a PERFORMANCE vehicle.
It's sad that you're putting noise supression a priority over performance...


-Ted

[vex]

Originally Posted by RETed

Not going to be possible, unless we're talking about something super complicated which implies super expensive...

Not necessarily

Ever seen a Ferrari exhaust?
It's basically one big muffler from engine to tailpipe!

There's a thought!

Chambered mufflers choke off too much performance - you'd need to build a 600hp engine to get 400hp after choking it off with all the chambered mufflers.

You want quiet?
Just don't rev over 2,000RPM.
You thinking you can rev up to redline past law enforcement?

No, but there are times I can not avoid going past 2000RPM in front of a LEO (see below)

I doubt stock is going to prevent you from getting looks.

You own a PERFORMANCE vehicle.
It's sad that you're putting noise supression a priority over performance...


-Ted

It is, but I have to do what I have to do. VA is notorious when it comes to exhaust systems. I have thus far received two exhaust tickets in my lifetime in Northern Virginia. 1 was on the stock exhaust and was a "defective exhaust" never mind it was completely stock without issue, I still got a ticket. The 2 was when I was driving up hill and could not maintain 2000RPM while not impeding traffic. It most certainly is a catch 22 if you ever need an example of one.

Ted, it appears I'm getting conflicting information between you and NoDOHC. This is what he has to say in a similar thread:

The chambered muffler relies largely on acoustical wave-cancelling and is therefore very frequency specific. This is offset by selecting several or many different chamber sizes to maximize the attenuated frequencies. The wave-cancelling looks like an inductor in series and a capacitor to ground on the waveform. It resists changes in flow rate to drive a high pressure pulse which will then propagate back the pipe at a destructive phase angle. to the original sound. With several chambers, the sound can be attenuated very well. Please note that a properly-designed chambered muffler will make little to no backpressure and on a long exhaust system, they may actually decrease backpressure over a mufflerless system. Chambered mufflers rely on wave inertial energy to cancel each subsequent wave, this means that low flow rates (exhaust velocities) will hurt their attenuation performance. For this reason, it is much better to run two chambered mufflers in series than in parallel.

[RETed]

Originally Posted by vex

Ted, it appears I'm getting conflicting information between you and NoDOHC. This is what he has to say in a similar thread:

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

[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.