I think of "drone" as something different... well, I think most everybody thinks of it this way? Drone does not equal Volume in the cabin. 2 different things. Drone is that throbbing resonance. More of a cyclic pressure that's annoying, draining, gives you a headache, wears you out, etc. It's like wind buffeting which doesn't really have any noise at all. That's different from LOUD. LOUD is something you can live with and/or enjoy. Drone is not. Resonators are not so much for noise reduction (although they do that to some extent) but there to break up the drone... Not to say that some people don't like drone or that it doesn't bother them.
By this definition then no, my Zoomers have no drone. They just hit a note between 65-70 that tends to put passengers to sleep. Funny how my angry HEMI model thread turned into a drone thread...lol
Like when you open the sunroof but no windows? Kind of a pressurized helicopter sound in the car with you?...If so, yea, hate that... i've never experienced that with any of the exhaust set ups i've had on this car...or ANY other vehicle i've owned in 22 years. I can hear the exhaust inside, but it isn't what you're describing.
I think its a one off, but it'd be cool to have around the house. And no prob, i like watching you all jaw about car stuff.
No doubt...my wife would HATE me, as would the dogs, kids, neighbors, birds, squirrels ect ect...screw em though, like you, i find a GOOD exhaust note to be musical and pleasant, where most find it obtrusive.
Maybe I didn't describe it quite well enough. The effect it has on you is like having the sunroof open with no windows. The sound can be that slow rythmic pulsing at whatever average sound level. Like a large sine wave. Can also be a noticeable increase in volume (but steady) at some resonance where if you were sitting outside the car you wouldn't hear any difference. That better? sigh... It's DRONE dammit.
Somewhere between a jackhammer and a dentist drill in annoyance levels?? I got a drone off the Zoomers when I had an exhaust leak. Just about everything in the cabin rattled including my teeth and it was very annoying which is why I got out and checked the rear and figured it out and got it fixed quick.
Okay, I have been corrected, its not a Hemi, I just have some sort of disorder that makes things SOUND just like a Hemi. Probably something to do with getting my ears blown out by a real live superbird starting up before dawn at Willow Springs just a matter of yards from me. Or something, anyway. It sounds pretty dammit and someone actually crafted the thing and it works! And I WANT one....hell, I wish my computer sounded that when it runs.
I stand corrected Dave...installed my BB reso delete pipes yesterday...I now know what "drone" is...At 2k RPM it's pretty obvious...the change in my ashtray rattles!! It's more of a vibration than a sound. But hey, i'm happy with them overall. I'll just have to drive under 60 MPH in the city, or auto stick it to 4th to get RPM's above 2k...it's a weird phenomenon, at ANY other RPM's it's fine, and sounds realllly good, deep and throaty. But at 2k, it can get down right annoying.
lol, well, there you have it young man. "resonance frequency". Every system has one... (actually more than one). http://en.wikipedia.org/wiki/Resonance http://auto.howstuffworks.com/muffler4.htm Resonators are usually tuned to cancel certain frequencies. There are some general frequencies common to engines/exhaust and then you can tune even further for specific systems. I think that's why the Corsa works so well. It was very specifically designed/tuned for the 6.1 LX's. I think the others make more of a generic auto exhaust that fits our cars. Because of that they all have some drone even though some have very little.
:maddy: you called me young...i knew i liked you for SOME reason. :sorry: And i agree with everything you said up there^^^ I've just never experienced this with any other vehicle in my 39 years....well, at least to this degree.
So Dave, help me out here...It's not the lack of reso's actually causing the drone, more so, the muffler is the culprit...the stock reso's just "fixed" what the muffler is doing/causing? With this logic, If I changed my muffler from stock to X, it could add to or remove the drone, or change the RPM in which it happens?? Whould a full free flowing muffler be better or worse???
Ok... This is going to be all BS and wild speculation (somebody should know this though) My understanding (weak) is that, without something to cancel it (damp it), you will have drone. Just depends on the resonance frequency. Think guitar string, Silver bridge, etc. There is some set of frequencies that the system (exhaust/car)resonates to. Change anything in the system and you will shift the resonance somewhat. I'm guessing that on all our cars, if you have drone, it's going to happen somewhere around 2K rpm. Roughly the same car, roughly the same length exhaust, V8s (which would give you about 133 exhaust pulses per second at 2K rpm), etc. So... I'm also guessing that the resonators are tuned to about that frequency. Might be that all cars like ours are about the same. Surely a 4 cylinder or 6 cylinder is going to have drone at different frequencies (might not even be in the operating rpm range). Don't forget about harmonic frequencies. Multiples. Here's an experiment. If you get drone at 2K see if you get drone at 4K (may not be anywhere near as bad and I suppose maybe not even detectable). I believe that mufflers designed to operate on the same principle (more than just absorbing sound with insulation material) are more general in that there are many reflective surfaces (baffles) at diffent lengths and creating different reflected waves and cancel noise over a very broad spectrum -- reduces volume at all rpm. Again, I think the Corsa's are tuned for that as well. That's why it sounds like you open cutouts when you floor it (you're going to be up over 4K). I think the mufflers were designed for that? So... I'm thinking that mufflers are going to change *volume* (and tone) over pretty much the entire range (of frequencies). Resonators are going to be tuned to a fairly narrow range just covering the resonance frequencies. If there's anything to that then, No, I don't expect changing that stuff with eliminate your drone. I'm guessing that, at best, it might shift it just a bit to a slightly different RPM. What do you think?
I think i need to learn more about sound waves and exhaust frequencies. Up until 04, i've never seen a resonator on a V8 vehicle, so something in the V8 world changed to give out those frequencies for them to be added/needed. What happened to a good ole 2 chamber FM to enjoy the sweet music of a robust V8? Maybe it's the shear amount of CFM volume we are producing with these heads, maybe it's the geometry of the flow itself, or maybe it's gremlin playing Mozart on a banjo in there. I think you have a pretty good grasp on what and why this phenomenon is happening, and what you wrote makes logical sense. A sound deadening muffler will likely lessen the drone, a sound amplifying muffler will likely increase it without the use of resonators tuned for that specific frequency we have to cancel it, like the Corsa. I really like the overall tone of my system now, but the 2k drone will get tiresome, and i'll likely change. I wonder if this would help if I installed it into the BB reso delete pipes. The Vortex Insert Cone, installed near the exit of the header collector or muffler outlet, provides a large friction area to reflect and dissipate sound energy, thus reducing the dB level. Because no significant backpressure has been introduced, the engine is still able to use the scavenge ability of a good header to create horsepower and torque. Dyno and track testing show significant noise reduction with little or no power loss.
I know nothing about the Vortex Insert Cone... but my first reaction would be snake oil. If it is reflecting sound it has surface area. If that surface area is blocking your exhaust flow it will create resistance. "provides a large friction area". Hahaha, wtf is up with that?
