Best Test Pipe for Drone Reduction
05-31-2017, 04:54 AM
#11
I guess this is why we aren't in the exhaust design business haha!
I think the fact of the matter is there are many, many variables to take into account... In an ideal world of course you want one pipe all the way through which is one diameter... But it's not an ideal world and I can't afford headers!
Just read about a chap who deadened down his fuel tank on a Subaru forum to reduce drone and had great success... May well give that a go first!
I think the fact of the matter is there are many, many variables to take into account... In an ideal world of course you want one pipe all the way through which is one diameter... But it's not an ideal world and I can't afford headers!
Just read about a chap who deadened down his fuel tank on a Subaru forum to reduce drone and had great success... May well give that a go first!
05-31-2017, 06:49 AM
#12
Ive been "Developing" my exhaust system for a while now and hope to be 3rd time lucky in reducing drone.
As Har-vey said, many more factors at work.
I have a Skunk2 exhaust with de-cat on my SC S2000, and it is LOUD. Also, as anyone with a Skunk2 will know, the drone is very high.
I used some calculation and assistance from work colleagues to develop a helmholtz resonator. Initial design was a 5" Dia resonator, unfortunately this reduced my ground clearance too much. I then went for a 3.5" dia (But longer to retain a similar volume). Did not work as well as the 5" and it "Buzzez" during acceleration around 3-4k rpm. Highly annoying. So as a final attempt, I will be fitting a 4.5" dia resonator next week.
Ground clearance not so much an issue any more as the new tyre dimensions raises the car 4mm and to avoid arch rub, I raised suspension another 10mm.
Quite a bit of good data on here:
https://www.s2ki.com/forums/s2000-un...-510969/page7/
Unfortunately to reduce Drone, you ideally need to get an audio recording, analyze it (Determine if its 2nd order or 4th order) and then either through trial and error or computer simulation, develop a helmholtz resonator to counter act the resonant frequency.
Good Luck!
As Har-vey said, many more factors at work.
I have a Skunk2 exhaust with de-cat on my SC S2000, and it is LOUD. Also, as anyone with a Skunk2 will know, the drone is very high.
I used some calculation and assistance from work colleagues to develop a helmholtz resonator. Initial design was a 5" Dia resonator, unfortunately this reduced my ground clearance too much. I then went for a 3.5" dia (But longer to retain a similar volume). Did not work as well as the 5" and it "Buzzez" during acceleration around 3-4k rpm. Highly annoying. So as a final attempt, I will be fitting a 4.5" dia resonator next week.
Ground clearance not so much an issue any more as the new tyre dimensions raises the car 4mm and to avoid arch rub, I raised suspension another 10mm.
Quite a bit of good data on here:
https://www.s2ki.com/forums/s2000-un...-510969/page7/
Unfortunately to reduce Drone, you ideally need to get an audio recording, analyze it (Determine if its 2nd order or 4th order) and then either through trial and error or computer simulation, develop a helmholtz resonator to counter act the resonant frequency.
Good Luck!
06-05-2017, 07:02 PM
#14
I did some research before buying a random exhaust, read a lot of good and bad things about certain systems before I pulled the trigger.
At first I was really tempted to buy the Invidia because I do like a nice rumble and it's the only road legal system in Belgium. But seems like alot of people had drone issues with this one as well so I stayed away from it even though I do have to change my current exhaust every year now for inspection.
In the end I decided to go for the J's 60RS dual with J's decat, great sound and no drone so this saved me alot of headaches and worries. My second choice was the Greddy SE V2 because this one also has the helmholtz pipe (just like oem) and seems to be a very good one as well.
I hope you find a solution though, I'm curious if there's actually an easy way to fix this drone issue without hacking up the exhaust.
At first I was really tempted to buy the Invidia because I do like a nice rumble and it's the only road legal system in Belgium. But seems like alot of people had drone issues with this one as well so I stayed away from it even though I do have to change my current exhaust every year now for inspection.
In the end I decided to go for the J's 60RS dual with J's decat, great sound and no drone so this saved me alot of headaches and worries. My second choice was the Greddy SE V2 because this one also has the helmholtz pipe (just like oem) and seems to be a very good one as well.
I hope you find a solution though, I'm curious if there's actually an easy way to fix this drone issue without hacking up the exhaust.
06-06-2017, 01:57 AM
#15
The OEM and most likely the GReddy has a 1/4 wave resonator tube. But designed in such a way that the one seen on the exhaust alone will not reduce drone. It works in conjunction with resonators placed inside the silencers.
If an exhaust has drone, there is very little that can be done about it if you dont want to cut and weld bits on. Adding either Helmholtz or 1/4 wave resonators will reduce / eliminate drone, but as mentioned, its not a quick and easy solution. (But one that works)
Good luck!
If an exhaust has drone, there is very little that can be done about it if you dont want to cut and weld bits on. Adding either Helmholtz or 1/4 wave resonators will reduce / eliminate drone, but as mentioned, its not a quick and easy solution. (But one that works)
Good luck!
06-06-2017, 01:59 AM
#16
I did some research before buying a random exhaust, read a lot of good and bad things about certain systems before I pulled the trigger.
At first I was really tempted to buy the Invidia because I do like a nice rumble and it's the only road legal system in Belgium. But seems like alot of people had drone issues with this one as well so I stayed away from it even though I do have to change my current exhaust every year now for inspection.
In the end I decided to go for the J's 60RS dual with J's decat, great sound and no drone so this saved me alot of headaches and worries. My second choice was the Greddy SE V2 because this one also has the helmholtz pipe (just like oem) and seems to be a very good one as well.
I hope you find a solution though, I'm curious if there's actually an easy way to fix this drone issue without hacking up the exhaust.
At first I was really tempted to buy the Invidia because I do like a nice rumble and it's the only road legal system in Belgium. But seems like alot of people had drone issues with this one as well so I stayed away from it even though I do have to change my current exhaust every year now for inspection.
In the end I decided to go for the J's 60RS dual with J's decat, great sound and no drone so this saved me alot of headaches and worries. My second choice was the Greddy SE V2 because this one also has the helmholtz pipe (just like oem) and seems to be a very good one as well.
I hope you find a solution though, I'm curious if there's actually an easy way to fix this drone issue without hacking up the exhaust.
06-06-2017, 06:22 AM
#17
I am not saying that anyone here is wrong in what they have said, not for a second. However, there is a clear and very distinctive difference in "drone" with the roof up, versus the roof down. Roof down I do not care about volume, the wind is going to be noisy anyway. Roof up and im either on a long drive or it's wet and miserable outside and I do not need my ears ringing when i'm already upset that my roof is in the wrong position, but has to be to avoid a puddle in my drivers seat 
Anyway on to my main point; with the roof up the drone sounds more like a vibration than it does an exhaust noise, and gives my ears almost the sensation I get in a club when i'm stood next to a subwoofer (not that i've done that in about 3 years!!). Which makes me think it simply cannot JUST be the exhaust to blame - the S2000 is a stripped out motor and isn't meant for acoustic refinement, as such the amount of sound insulation around the fuel tank and boot floor is pretty much non-existent. I believe the vibrations caused by the noise of the exhaust vibrates the fuel tank and in turn the boot, which reverbs all the way around the cabin, causing that horrid ear ringing sensation you get at 3500-4300 rpm, or on throttle lift.
My plan is to put some 4mm Silent Coat on the exterior of the fuel tank once I have verified that the exhaust doesn't make that area too hot. Once I've done that, either some 2mm or more 4mm all around the boot where the toolkit is supposed to go, and then around the rear bulkhead.
Think of it like this: If you put yourself in a metal cube and had a couple of sub woofer running at ~98-102db around a meter away from you, inches away from the metal outside, i am pretty sure you would have a headache within minutes. Insulate and sound proof the cube = no more headache, or greatly reduced.
I have no proof to back this up other than extensive research i've done on several forums for various manufacturers about drone, exhaust systems, sound insulation, studio booths, etc.
If you have a quick look at this youtube video... Imagine the exhaust is a hammer constantly tapping the panel rather than one big hit...
I am planning on buying the materials to try this later on this month, i'll update this thread and my project thread with some videos, pics, etc. Hopefully it will all be worth it!
Edit; I should also add here that obviously the best option is to buy an exhaust system with volume levels you are comfy with in the god damn first place, but if unfortunately like me, you cannot justify dropping the best part of a grand on a system in one hit, this may just work out as a reasonably comfortable alternative, which is why I am continuing to pursue it.
Anyway on to my main point; with the roof up the drone sounds more like a vibration than it does an exhaust noise, and gives my ears almost the sensation I get in a club when i'm stood next to a subwoofer (not that i've done that in about 3 years!!). Which makes me think it simply cannot JUST be the exhaust to blame - the S2000 is a stripped out motor and isn't meant for acoustic refinement, as such the amount of sound insulation around the fuel tank and boot floor is pretty much non-existent. I believe the vibrations caused by the noise of the exhaust vibrates the fuel tank and in turn the boot, which reverbs all the way around the cabin, causing that horrid ear ringing sensation you get at 3500-4300 rpm, or on throttle lift.
My plan is to put some 4mm Silent Coat on the exterior of the fuel tank once I have verified that the exhaust doesn't make that area too hot. Once I've done that, either some 2mm or more 4mm all around the boot where the toolkit is supposed to go, and then around the rear bulkhead.
Think of it like this: If you put yourself in a metal cube and had a couple of sub woofer running at ~98-102db around a meter away from you, inches away from the metal outside, i am pretty sure you would have a headache within minutes. Insulate and sound proof the cube = no more headache, or greatly reduced.
I have no proof to back this up other than extensive research i've done on several forums for various manufacturers about drone, exhaust systems, sound insulation, studio booths, etc.
If you have a quick look at this youtube video... Imagine the exhaust is a hammer constantly tapping the panel rather than one big hit...
I am planning on buying the materials to try this later on this month, i'll update this thread and my project thread with some videos, pics, etc. Hopefully it will all be worth it!
Edit; I should also add here that obviously the best option is to buy an exhaust system with volume levels you are comfy with in the god damn first place, but if unfortunately like me, you cannot justify dropping the best part of a grand on a system in one hit, this may just work out as a reasonably comfortable alternative, which is why I am continuing to pursue it.
Last edited by Matt1783; 06-06-2017 at 07:23 AM.
06-06-2017, 08:36 AM
#18
I doubt you will notice much if any difference, it's not the lack of sound deadening that's the problem it's the exhaust.
You don't have any idea what brand it is by the way or any pictures?
You don't have any idea what brand it is by the way or any pictures?
06-06-2017, 10:32 PM
#19
I haven't tried it without the testpipe though, maybe people do have issues with these when using the oem cat but so far no drone here when driving with a test pipe.
It's quite loud in vtec but it actually has a civilised sound when driving normal, definately not what you'd expect from J's Racing.
I would definately stay away from the single exit J's exhausts though, they're way too loud even for me...
06-06-2017, 10:36 PM
#20
One thing to remember is that the S2000 has a rather small cabin and the exhaust runs very close to it. Drone is a direct product of the exhaust and influenced by factors that can change the flow of air. (Larger dia, de-cat, silencers, manifods etc..)
If you wish to reduce drone, you need to counteract the sound frequency. From my studies that shows to be around 116Hz @ 3500rpm. This is the range I targeted as the drone seems to be worst in the range of 3-4K rpm.
As mentioned by Flanders, sound deadening will have little effect. Will have some, but probably not as much as you would think.
In my opinion, your solutions are any of the following:
- Put up with the drone. (Not nice on long journeys)
- Change exhaust to standard and do UK Exhaust Mod.
- Change exhaust to a known and tested one with little to no drone. (Very rare on aftermarket exhausts)
- Add a 1/4 Wave Branch resonator.
- Add a Helmholtz resonator.
I opted for the Helmholtz as it covers a wider range of frequencies, so will work better over a larger rev range. The 1/4 Wave works in a similar way, but targets a narrower band.
Will be interested to see your opinion and results with the sound matting though.
If you wish to reduce drone, you need to counteract the sound frequency. From my studies that shows to be around 116Hz @ 3500rpm. This is the range I targeted as the drone seems to be worst in the range of 3-4K rpm.
As mentioned by Flanders, sound deadening will have little effect. Will have some, but probably not as much as you would think.
In my opinion, your solutions are any of the following:
- Put up with the drone. (Not nice on long journeys)
- Change exhaust to standard and do UK Exhaust Mod.
- Change exhaust to a known and tested one with little to no drone. (Very rare on aftermarket exhausts)
- Add a 1/4 Wave Branch resonator.
- Add a Helmholtz resonator.
I opted for the Helmholtz as it covers a wider range of frequencies, so will work better over a larger rev range. The 1/4 Wave works in a similar way, but targets a narrower band.
Will be interested to see your opinion and results with the sound matting though.