Do test pipes create drone?

[bradboyd80]

I've been wanting a bit more out of the exhaust as far as sound and power go, but I'm not ready to spend upwards of $500 for a CBE or quality DP. So that leaves me with searching for a test pipe, or removing a resonator or two.

So my question for those of you with either one: Do you get any drone on the highway? I have a gf with two kids so I don't want the exhaust to be too loud. Just want it to sound a tad deeper.

 

[MSMS3]

I have both a catless dp and a test pipe, so my info might not apply. A couple observations, for what they may be worth.

1. Don't spend your money on a CBE if you are searching for power. The stock CBE is extremely well flowing. I consider its flow rate to be higher than the maximum exhaust side output of the stock K04 turbo. You have to get whp up above 300 whp before you will notice any gains from a bigger CBE.

2. The exhaust restrictions are all upstream of the CBE. The downpipe is very restrictive. It has a sharp angle coming out of the turbo and a very poor shape. It has a restrictive cat. Then the car's second cat, in the separate section where your test pipe will go, is also restrictive.

Accordingly, you will pick up a little power in the 5-10 hp range by going with a test pipe. it's a simple 10 minuite install. Don't expect a huge gain, but it does help.

As to your drone question, I can tell you that the combo of the catless dp/rp shown in my sig did produce horrible, very loud, very intrusive drone into the cabin in the 2500 rpm range -- right where you will be cruising at 60-65 mph, especially when decelerating down through that range or cruising in it.

I fixed the drone by putting a 3 inch straight through high flow reso (see sig) in the middle of the race/test pipe by cutting out a section and welding the reso in. The reso I used is such a high flow item that there is no reduction in flow. I can't tell you if you'll get drone with just the test pipe alone.

Try it. You will pick up a little power. It will change the sound of your exhaust. You can add the reso if it bothers you.

Hope this helps.

 

[bradboyd80]

Yeah, that helps a bit. Thanks.

I must have watched a dozen videos on youtube. It seems that at least at idle, a test pipe alone doesn't increase tone much at all. So I was debating removing one of the resonators AND going with a test pipe. I guess I'll just do one at a time and see how it sounds. I was just worried about highway drone. And for the record, I usually do about 5-10 over which would put me at 75-80 for the majority of my road trips. Back and forth to work really doesn't concern me as much since I do that alone.

 

[MSMS3]

Yeah, that helps a bit. Thanks.

I must have watched a dozen videos on youtube. It seems that at least at idle, a test pipe alone doesn't increase tone much at all. So I was debating removing one of the resonators AND going with a test pipe. I guess I'll just do one at a time and see how it sounds. I was just worried about highway drone. And for the record, I usually do about 5-10 over which would put me at 75-80 for the majority of my road trips. Back and forth to work really doesn't concern me as much since I do that alone.

I understand. But you should drive around a bit and watch your tach. You'd be surprised how much time you spend at and around 2,500 rpm. The drone was worst for me when coming back down into that range when slowing down or when driving in stop and go traffic.

I think you have a good plan to put the test pipe in first and see what it sounds like before messing with the resos in the CBE. It will raise volume a little bit.

 

[bradboyd80]

Oh I gotcha....on my work trips, I usually try to keep my RPMs in that range to keep my MPGs up. I would hate for it to drone like crazy for the entire 40 min drive to work. Much less a 12 hr drive to VA and NC.

 

[Saskatchewan17]

I also have a resonated TP. A HUGE dynomax reso at that. Drone has been reduced from the stock TP with the reso deleted stock CBE. It is all around quieter in the cabin and I can barely hear the car at 2k-2,500 RPM. It does drone on downshifts a bit, but it really makes a great balance of a nice tone and quiet at cruising speed.

 

[08cosmic3]

I removed my drone and made the car quieter by removing the 2nd resonator and welding in a Magnaflow 6" dia. resonator in it's place. NO DRONE and the car is quieter than stock. No loss of power either, ran 13.3 at 107.79 with mods below.

Magnaflow model # 12616 satin finish (cheaper) 14616 polished finish (Add $$)

 

[creedns]

drone ftw! why? guess how much road noise i hear lol

 

[bradboyd80]

Haha....yeah I'm sure it might drown out road noise, but I don't want the kiddos to be deaf by the age of 10. LOL. Thanks for all the input fellas.

 

[MS3inDC]

I really find this thread to be a little silly. I understand it can be done, but its like your asking for two things that oppose each other. You want more sound out of your exhaust, but you want to keep it quiet...?

IMO, if you want sound, you get drone. Thats all part of having more sound out of your exhaust is to hear it... at all times!! Not just when its convenient. You hear it when you accelerate, you hear it when you cruise, you hear it when you decelerate, you hear it as long as the car is running.

IMO, if you want quiet, you don't do anything to your exhaust. You leave it stock and just don't touch it.

Enhancing your exhaust for sound means making it more audible.

 

[bradboyd80]

All I wanted to know is whether or not a testpipe causes drone. I just dont want a ton of drone. I'm really only curious as to whether the few extra ponies picked up are worth the extra noise. I never said I wanted it to be quiet. I just don't want the exhaust sound to be TOO loud in the cabin. Sorry, but I don't find that silly. Now take your criticism elsewhere please.

 

[Darth Vader]

If you're sticking with the stock catback, it's pretty minor. The exhaust note of this car is pretty muted. Of course, my last performance car was a supercharged 5.0 with a 2.5 inch Flowmaster 2 chamber exhaust so, pretty much everything is muted after that. I think you'll not be bothered by jst a TP on the car. It sounds damn good when you run a nice DP + TP. You'll want to open the windows to listen to it....

 

[MSMS3]

I really find this thread to be a little silly. I understand it can be done, but its like your asking for two things that oppose each other. You want more sound out of your exhaust, but you want to keep it quiet...?

IMO, if you want sound, you get drone. Thats all part of having more sound out of your exhaust is to hear it... at all times!! Not just when its convenient. You hear it when you accelerate, you hear it when you cruise, you hear it when you decelerate, you hear it as long as the car is running.

IMO, if you want quiet, you don't do anything to your exhaust. You leave it stock and just don't touch it.

Enhancing your exhaust for sound means making it more audible.

Sorry, but this is completely, totally incorrect. This misunderstanding arises from a fundamental mistake in understanding the way that a sound wave is magnified when it enters a resonating accoustic chamber, such as through the floorboard and into the interior of our cars. In certain frequency ranges, the entire inside of the car magnifies certain sound frequencies. It's an accoustic issue.

Change in tone and changes in volume are NOT, absolutely NOT the same thing as drone. Drone is a very irritating intrusion of narrow rpm, narrow frequency sound into the cabin of the car during crusing or when decelerating, which then combine with the accoustic resonance of the entire cabin to make the sound much louder than at rpms that are lower or higher. Our cars seem to form a highly effecient accoustic chamber that matches the frequency of the exhaust at approximately 2,500 rpm and a few hundred rpm on each side of that. There is a little drone left in the stock exhaust, although most has been tuned out with the stock CBE. But when you start opening up the flow upstream with the downpipe or the midpipe, this increases flow and drone goes up. This can be addressed easily and cheaply.

We can enjoy a healthy sounding exhaust, even raise the volume considerably and still avoid that cabin resonance that happens when the entire inside of the car becomes a resonant sound chamber for certain very narrow rpm bands with poorly tuned exhaust systems.

Carefully selected straight through resonators of the correct size and shape to attenuate the drone are the solution. Accoustic engineers can figure this out by measurement. We have to do this by trial and error. And done properly a good straight through reso will not change the overall volume or sound of the exhaust when you push the go pedal to the floor nor do they decrease power. But it can kill the headache producing drone at cruise or deceleration through the offending rpm range.

I solved my particular drone problem with a single very specifically selected reso welded into the middle of the race pipe for less than $100.

To OP: Try the test pipe. They are cheap. I don't know if it will create drone by itself. If it does, consider putting in a straight through reso in the test pipe or as close to it in the front section CBE as you can. A muffler shop can do this simple task very inexpensively.

 

[matsuda]

All I wanted to know is whether or not a testpipe causes drone. I just dont want a ton of drone.

Fortunately, no.
I couldn't tolerate it otherwise.

 

[matsuda]

I really find this thread to be a little silly. I understand it can be done, but its like your asking for two things that oppose each other. You want more sound out of your exhaust, but you want to keep it quiet...?

IMO, if you want sound, you get drone.

Don't you know the difference between bass and treble?

 

[bradboyd80]

Sorry, but this is completely, totally incorrect. This misunderstanding arises from a fundamental mistake in understanding the way that a sound wave is magnified when it enters a resonating accoustic chamber, such as through the floorboard and into the interior of our cars. In certain frequency ranges, the entire inside of the car magnifies certain sound frequencies. It's an accoustic issue.

Change in tone and changes in volume are NOT, absolutely NOT the same thing as drone. Drone is a very irritating intrusion of narrow rpm, narrow frequency sound into the cabin of the car during crusing or when decelerating, which then combine with the accoustic resonance of the entire cabin to make the sound much louder than at rpms that are lower or higher. Our cars seem to form a highly effecient accoustic chamber that matches the frequency of the exhaust at approximately 2,500 rpm and a few hundred rpm on each side of that. There is a little drone left in the stock exhaust, although most has been tuned out with the stock CBE. But when you start opening up the flow upstream with the downpipe or the midpipe, this increases flow and drone goes up. This can be addressed easily and cheaply.

We can enjoy a healthy sounding exhaust, even raise the volume considerably and still avoid that cabin resonance that happens when the entire inside of the car becomes a resonant sound chamber for certain very narrow rpm bands with poorly tuned exhaust systems.

Carefully selected straight through resonators of the correct size and shape to attenuate the drone are the solution. Accoustic engineers can figure this out by measurement. We have to do this by trial and error. And done properly a good straight through reso will not change the overall volume or sound of the exhaust when you push the go pedal to the floor nor do they decrease power. But it can kill the headache producing drone at cruise or deceleration through the offending rpm range.

I solved my particular drone problem with a single very specifically selected reso welded into the middle of the race pipe for less than $100.

To OP: Try the test pipe. They are cheap. I don't know if it will create drone by itself. If it does, consider putting in a straight through reso in the test pipe or as close to it in the front section CBE as you can. A muffler shop can do this simple task very inexpensively.

Thanks for the thorough explanation. Now I can say I've learned something new today. (thumb)

I greatly appreciate all the feedback. I'll have to try out the test pipe and go from there. If it creates too much drone, I'll try out the resonator in the test pipe idea.

 

[MS3inDC]

Don't you know the difference between bass and treble?

I do, and I also understand the difference between the resonance of sound and drone. But apparently they are one in the same in this thread

"...a drone is a harmonic or monophonic effect or accompaniment where a note or chord is continuously sounded..."

"...resonance is the tendency of a system (usually a linear system) to oscillate with larger amplitude at some frequencies than at others..."

in this thread, resonance is what is being discussed, not drone. that sound made right around 2,500 rpm... resonance...

 

[bradboyd80]

I really don't care about the difference between resonance and drone. Either way, my point got across, people knew what I was talking about, and I received good feedback. But I guess you just felt a need to show you have a bigger nutsack than all the other monkeys?

 

[MS3inDC]

I really don't care about the difference between resonance and drone. Either way, my point got across, people knew what I was talking about, and I received good feedback. But I guess you just felt a need to show you have a bigger nutsack than all the other monkeys?

not about proving anything, just understanding

 

[bradboyd80]

At least now I can say I learned something new today.