Lets talk about drone (i.e. what is, and what is not)
 

This has been a hot topic here, and a recent PM inspired me to throw this post up. One thing to remember about drone, is it is like porn, in that it is hard to define, but you know it when you see it (or in this case hear it). Also, drone is very subjective. What is drone to one person, is not drone to another.

One point I want to make up front is that PRETTY MUCH EVERY EXHAUST DRONES!

Now that I have your attention..here is where the interesting part is. Pretty much every exhaust is gonna make a droning noise at some point in the RPM range. There is really no way around it without making the car super quiet. That being said, most exhaust manufactuers tune the exhaust to make it's "droning" noise at something other than highway cruising RPM. For instance..if someone asks me if the Borla Stinger drones on an M6, I would say no. But to me the definition of no drone is at high way speeds between 55-70mph at 1000-1500 rpms or so. That being said..at around 2000 RPM's toolling in traffic, it makes a noise that could be considered a "drone". I have a supercharged GTO with a Bassani exhaust. Same story..non existant drone on the highway, but at 40mph it drones.

This (along with AFM) is why you see some exhaust manufactuers make different exhausts for the M6 and A6..because at highway speeds, they have a different crusing RPM. If you design an exhaust for an M6 to not drone, when you put it on an A6 car that has a higher cruising rpm, it may drone. A6 Corvettes are very hard to buy no drone exhaust systems for because almost every Vette system is designed for the M6. Not only that..the A6 Vettes come with two different axle ratios that move the cruising RPM around evene more.

I guess what I am saying is-

A.) When someone says an exhaust has no drone, they are refering to highway crusing speed and RPM.

B.) Almost every aftermarket exhaust has the potential to make a droning sound at some place in the RPM range..so don't be surpised to hear it at 40-55 or 75+. It's not so much the speed, as much as at a certain RPM. You can get out of drone sometimes by shifting to a different gear.

C.) If you can't have drone anywhere because of wife or kids you really are better off keeping the stock mufflers and getting a set of cutouts or something. The supposed drone I mentioned in my Camaro at 40 with the Borla Stinger is nowhere near offensive..but every person is different.

^^^Thanks

well stated, now all you have to do is make a decision. The end result is always the same: to gain (performance) you lose something. :bow:

Only drone that would bother me is if it rattled something.

Other than that the louder the better =p

great post!!!!

Being the king of homemade low $ systems drone can be one PITA and the only place I don't like it, is at cruise speed.

But often find playing with the tips can help change that.

My newest V8 dual system that is nutting but some straight shot cherrybombs n straight pipes had a terrible drone at cruise.

I just played with a extra pieces of pipe that slipped into the end, sort of like changing pitch on a slide horn, more or less pipe.

Ended up just needing a small 3-4 in piece jammed flush into the end of each.
That tiny lip or step at the end made it go away at cruise speed.

If Im at HW speeds the glaspacks cover up any drone.

Just takes some personal attention, I like your method =)

Good post. It's so funny to hear people wanting a louder car, but don't want to hear the exhaust. You're just not going to get both. I have a Borla Stinger cat-back, and while I can definitely hear some drone in the 2000 rpm range, it really doesn't bother me (especially since I tuned out the AFM). If it starts getting on my nerves I'll put some Dynamat in the trunk and be done with it.

Is there a technical definition for drone? Is it due to a flow-induced resonance? Do the exhaust manufacturers ever make detailed measurements and perform engineering analysis of the acoustics, system vibration, and fluid dynamics? This is what I do for a living, albeit for underwater applications which are trying to do the opposite of most Camaro owners, i.e., be stealthy.

Yes ... As you probably already know it's called resonant frequency, and everything in life has it. And yes the manufactures spend a ton of money in the research of their exhaust systems.

I have the SS, A6, with Borla S and what i here is not a drone. At highway cruising no drone, but when putting around in town it gets in a zone that sounds like a 4-cylinder, drives me crazy. I have to speed up or slow down. Pretty sure the sound I hear is the AFM. Sure wish you did not lose your warranty by tuning AFM out.

Hit the head on the nail. This is the first time I have seen someone mention sound deadening being the solution to interior cabin noise. All of my previous cars had headers, full cat back systems, super chargers etc. I wanted them to sound like an angry lion but didnt want that angry lion in the back seat all the time. I would lay down different types of Dynamat from the fire wall back, in the trunk etc. Good way to keep the "Angry Drone" out.

"Angry Drone" hmmmm

I think my people confuse dr

What is drone? I always thought it was that RPM where the exhaust gets VERY LOUD. I believe if you want an exhaust that sounds deep / rumbles the exhaust will drone, they go hand in hand. I have never heard an aftermarket exhaust not have drone but I have heard the Corsa somewhat resolves it by using baffles tuned to cancel the resonant frequency? Never heard one in person though so I couldn't comment. Anyone else?

Also, I love my Borlas but try driving 5 hours with drone, it's not pleasant in the least. At least that is my opinion.