When talking about aftermarket exhausts, I hear ppl talk about "resonance", and its seems like something negative. What is it? Is it like an echo?

 

not really a noise, it's more like a terrible sound vibration ... when you hear/feel it you will know, just get into a car with a Fab Speed around 2800 rpm

 

It vibrates the bones in your ears. It hurts.

 

Actually, that is a very good question.

Drone to a lot of people means the resonance or harmonic commonly found between 2000 and 3000 rpms on a lot of aftermarket exhaust systems. In a lot of cases, the "drone" can be so bad, that the interior bits of the car or the loose coins in your ashtray may vibrate. But what really irritates people about drone is that it can make your eardrums vibrate, making the driving experience uncomfortable at times. It is most evident when cruising on the highway at a steady speed.

Now, why your question is so good is because some people are more sensitive to drone that others, and when one person says that their aftermarket exhaust does not drone but someone else with the same system says it does, it becomes confusing.

Regardless, once an exhaust is designed to produce more power than the stock one it is replacing, a common downside is drone and it is very difficult to massage out in the design. However, this is where one of main differences lies between exhaust systems. Some just open up the pipes to make more power, and some take more sophistacated methods to create the same power while minimizing or eliminating the dreaded drone.

When designing our 996TT systems (not to toot our own horn too much), we spent several *months* and 7 different designs to eliminate the drone that was apparent between 2-3000 rpms. It meant road testing up and down hills, on the hiway, in different ambient conditions, and with sound frequency and level measurement devices. Ultimately, the only real test was to have several different people drive the car in its final prototype phases and give us feedback.

Drone can be somewhat subjective, but the bottom line is that if an exhaust sound irritates you more than pleases you after a long trip, it is most likely droning.

If you would like to talk further, please email me.
mike@awe-tuning.com

Here is a link to our 996TT exhaust page.
http://www.awe-tuning.com/pages/shar...L=996ttexhaust

 

Great answer!

A high quality aftermarket company that conducts REAL R & D work with REAL engineers.

Shame your located so far away from Chicago. I'd be honored to work with you.

I am somewhat in the same field of work myself. I work for Senior Automotive in Bartlett IL.

Here is a quick lesson on Resonance --> http://www.colorado.edu/physics/2000...ing_wave2.html

 

Mike, would it be wishfull thinking that you would have a 986 muffler in the semi-near future?

Bro

 

resonance is the frequency at which something wants to vibrate at naturally. Think of a swing set, it swings back and forth every few seconds. Once you get up to speed it takes very little effort to stay there, but takes a bit to get up to speed.

Same thing with sound, at certain frequencies, it takes only a little bit of energy to produce a lot of movement (vibration).

Depending on how the exhaust is engineered and what resonance frequency it's tuned at, it can be a bone and ear jarring racket that tries to vibrate you car to pieces or make for a nice smooth loud exhaust tone.