Major drone with 14" Magnaflow, Need Help
01-15-2015, 08:52 AM
#11
Put the resonator back on, it's a drone absorber.
01-15-2015, 09:30 AM
#12
You may speak from YOUR experience. That doesn't mean it will be everyone's experience. I am 54 and have owned "loud" cars and trucks my whole life including daily drivers. My '14 Lariat had a Solo-X catback on it within a month of owning it. It is one of the loudest exhausts and sounds great without drone. Brings a smile to my face everytime I start it! Some of us never get tired of that sound so personal "experience" is just that, your personal experience.
To the OP, like some have said, you might try a small resonator in front of your muffler. You also might go to your local muffler shop and see if they have any suggestions.
To the OP, like some have said, you might try a small resonator in front of your muffler. You also might go to your local muffler shop and see if they have any suggestions.
Lol jk
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71_340 (01-15-2015)
01-15-2015, 10:24 AM
#14
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I dealt with this very issue on multiple vehicles (Jeep Wrangler and Mustang mostly). I went through SEVERAL exhaust setups and it's all trial and error. I have a set of 40 series Flowmasters that sounded awesome, but the drone made your brain rattle. Like others have said, you could try resonators. Also like others have said, go to your local muffler expert and ask them if adding a bend somewhere in the pipe would fix the issue. On my Jeep it was as simple as adding a few curves in the pipe and the drone was gone. But, like I said, it's all trial and error.
Edit.... Here's a post on another forum where the guy figured out how to get rid of his drone by adding an extension to his pipe. His isn't an F150 but the concept would apply to any vehicle with drone...
-------------------------------------------------------------------------------------------
"So I had the FI style exhaust and I agree its the deepest exhaust I've heard on a 370Z and sounds AMAZING, especially above 3000rpms. However, the downside is the drone between 2200-2800rpms was bad, worse for others depending on your tolerance, and was prevalent at cruising RPMS.
Being a mathy person, I figured I could fix the problem by hitting it at the source, what causes the drone. Drone is caused by the pipe resonance so to combat this, you need to use the exhaust wavelengths against themselves to cancel them out.
One way to do this is to put on a chambered muffler which breaks up the sound waves and avoids hitting the natural pipe resonance frequency. This also kills some performance because it hurts flow. This is how Corsa mufflers work as they are tuned per car to break up the frequency at which the exhaust system naturally resonates without affecting the flow. However they are very expensive and they dont make one for our car.
Standard resonators (Magnaflow, OEM, etc) are excellent at destroying high frequency resonance in the upper RPM ranges (3k plus) but dont do much for low frequency resonance (100khz-140khz). Changes in pipe size and tailpipe length can push the natural resonance frequency for the exhaust out of the normal RPM range but unfortunately with the FI style and most straight through exhausts I've seen on 370Z's, resonance happens from 2krps to 3krpms frequently and can be very annoying.
SO, finally the fix:
To get rid of drone (pipe resonance), you need to cancel out those specific pipe resonant frequencies. To do this without using a chambered muffler you can use whats called a Side Branch Resonator.
The side branch resonator is a pipe, around the same size as the exhaust pipe, which T's off the OEM pipe between the rearmost mufflers and the exhaust tips. For the FI style, it comes off at 90 degrees from that pipe and should go out straight across to the other side (in the area where the OEM hunker muffler was). One end is welded to the opening on the OEM pipe and the other end is welded shut with a cap, no filling in the pipe at all. The cap reflects the sound back into the OEM pipe. The length of the side branch pipes matters a LOT! To cancel out the frequencies you need to have them reflect back at a quarter wavelength from the side pipes that T off the main pipe. The simple answer is for the FI setup, if you have heavy resonance at 2500rpms (ish) then you need 28" side branch resonation pipes, one per side.
I did this on my car, first with 22" side branches and had no luck. After re-doing my math and using some Audacity frequency analysis, I figured out that they had to be 27-28" to work at the RPM I wanted. Longer pipes tune out frequencies lower in the RPM range. Shorter pipes (increasingly less effective) hit the higher rpms. I had the mechanic fix the pipes to 28" and VOILA, absolutely zero drone from 2200rpms to 2800rpms. At 2000rpms there is a slight rumble in the cabin, but no drone. Same at 3000rpms which changes into an aggressive purr. Absolutely nothing changed about the exhaust sound or performance in any way besides the reduction (went from heavy drone that was very uncomfortable to NO DRONE) in drone. Plus, its all tucked up behind the bumper where the muffler used to be so you cant tell.
I hope this helps for those who hate the droning but want to keep the performance, sound and looks! I guarantee that it works amazingly, others on other car forums have had the same results when you use the right length of side branch resonators. If you dont mind the drone or dont want to cut into your gorgeous exhaust, enjoy as is.
Diagram is below and more info for those who want it, will have pics soon! Red and black are two pipes, each about 28" long total, capped at the end furthest from the connection to the OEM pipe. They meet the OEM pipes at 90 degrees and do not connect, they just pass each other on a side and are welded together for stability."
Edit.... Here's a post on another forum where the guy figured out how to get rid of his drone by adding an extension to his pipe. His isn't an F150 but the concept would apply to any vehicle with drone...
-------------------------------------------------------------------------------------------
"So I had the FI style exhaust and I agree its the deepest exhaust I've heard on a 370Z and sounds AMAZING, especially above 3000rpms. However, the downside is the drone between 2200-2800rpms was bad, worse for others depending on your tolerance, and was prevalent at cruising RPMS.
Being a mathy person, I figured I could fix the problem by hitting it at the source, what causes the drone. Drone is caused by the pipe resonance so to combat this, you need to use the exhaust wavelengths against themselves to cancel them out.
One way to do this is to put on a chambered muffler which breaks up the sound waves and avoids hitting the natural pipe resonance frequency. This also kills some performance because it hurts flow. This is how Corsa mufflers work as they are tuned per car to break up the frequency at which the exhaust system naturally resonates without affecting the flow. However they are very expensive and they dont make one for our car.
Standard resonators (Magnaflow, OEM, etc) are excellent at destroying high frequency resonance in the upper RPM ranges (3k plus) but dont do much for low frequency resonance (100khz-140khz). Changes in pipe size and tailpipe length can push the natural resonance frequency for the exhaust out of the normal RPM range but unfortunately with the FI style and most straight through exhausts I've seen on 370Z's, resonance happens from 2krps to 3krpms frequently and can be very annoying.
SO, finally the fix:
To get rid of drone (pipe resonance), you need to cancel out those specific pipe resonant frequencies. To do this without using a chambered muffler you can use whats called a Side Branch Resonator.
The side branch resonator is a pipe, around the same size as the exhaust pipe, which T's off the OEM pipe between the rearmost mufflers and the exhaust tips. For the FI style, it comes off at 90 degrees from that pipe and should go out straight across to the other side (in the area where the OEM hunker muffler was). One end is welded to the opening on the OEM pipe and the other end is welded shut with a cap, no filling in the pipe at all. The cap reflects the sound back into the OEM pipe. The length of the side branch pipes matters a LOT! To cancel out the frequencies you need to have them reflect back at a quarter wavelength from the side pipes that T off the main pipe. The simple answer is for the FI setup, if you have heavy resonance at 2500rpms (ish) then you need 28" side branch resonation pipes, one per side.
I did this on my car, first with 22" side branches and had no luck. After re-doing my math and using some Audacity frequency analysis, I figured out that they had to be 27-28" to work at the RPM I wanted. Longer pipes tune out frequencies lower in the RPM range. Shorter pipes (increasingly less effective) hit the higher rpms. I had the mechanic fix the pipes to 28" and VOILA, absolutely zero drone from 2200rpms to 2800rpms. At 2000rpms there is a slight rumble in the cabin, but no drone. Same at 3000rpms which changes into an aggressive purr. Absolutely nothing changed about the exhaust sound or performance in any way besides the reduction (went from heavy drone that was very uncomfortable to NO DRONE) in drone. Plus, its all tucked up behind the bumper where the muffler used to be so you cant tell.
I hope this helps for those who hate the droning but want to keep the performance, sound and looks! I guarantee that it works amazingly, others on other car forums have had the same results when you use the right length of side branch resonators. If you dont mind the drone or dont want to cut into your gorgeous exhaust, enjoy as is.
Diagram is below and more info for those who want it, will have pics soon! Red and black are two pipes, each about 28" long total, capped at the end furthest from the connection to the OEM pipe. They meet the OEM pipes at 90 degrees and do not connect, they just pass each other on a side and are welded together for stability."
Last edited by discodave; 01-15-2015 at 10:30 AM.
01-15-2015, 10:49 AM
#15
Senior Member
I dealt with this very issue on multiple vehicles (Jeep Wrangler and Mustang mostly). I went through SEVERAL exhaust setups and it's all trial and error. I have a set of 40 series Flowmasters that sounded awesome, but the drone made your brain rattle. Like others have said, you could try resonators. Also like others have said, go to your local muffler expert and ask them if adding a bend somewhere in the pipe would fix the issue. On my Jeep it was as simple as adding a few curves in the pipe and the drone was gone. But, like I said, it's all trial and error.
Edit.... Here's a post on another forum where the guy figured out how to get rid of his drone by adding an extension to his pipe. His isn't an F150 but the concept would apply to any vehicle with drone...
-------------------------------------------------------------------------------------------
"So I had the FI style exhaust and I agree its the deepest exhaust I've heard on a 370Z and sounds AMAZING, especially above 3000rpms. However, the downside is the drone between 2200-2800rpms was bad, worse for others depending on your tolerance, and was prevalent at cruising RPMS.
Being a mathy person, I figured I could fix the problem by hitting it at the source, what causes the drone. Drone is caused by the pipe resonance so to combat this, you need to use the exhaust wavelengths against themselves to cancel them out.
One way to do this is to put on a chambered muffler which breaks up the sound waves and avoids hitting the natural pipe resonance frequency. This also kills some performance because it hurts flow. This is how Corsa mufflers work as they are tuned per car to break up the frequency at which the exhaust system naturally resonates without affecting the flow. However they are very expensive and they dont make one for our car.
Standard resonators (Magnaflow, OEM, etc) are excellent at destroying high frequency resonance in the upper RPM ranges (3k plus) but dont do much for low frequency resonance (100khz-140khz). Changes in pipe size and tailpipe length can push the natural resonance frequency for the exhaust out of the normal RPM range but unfortunately with the FI style and most straight through exhausts I've seen on 370Z's, resonance happens from 2krps to 3krpms frequently and can be very annoying.
SO, finally the fix:
To get rid of drone (pipe resonance), you need to cancel out those specific pipe resonant frequencies. To do this without using a chambered muffler you can use whats called a Side Branch Resonator.
The side branch resonator is a pipe, around the same size as the exhaust pipe, which T's off the OEM pipe between the rearmost mufflers and the exhaust tips. For the FI style, it comes off at 90 degrees from that pipe and should go out straight across to the other side (in the area where the OEM hunker muffler was). One end is welded to the opening on the OEM pipe and the other end is welded shut with a cap, no filling in the pipe at all. The cap reflects the sound back into the OEM pipe. The length of the side branch pipes matters a LOT! To cancel out the frequencies you need to have them reflect back at a quarter wavelength from the side pipes that T off the main pipe. The simple answer is for the FI setup, if you have heavy resonance at 2500rpms (ish) then you need 28" side branch resonation pipes, one per side.
I did this on my car, first with 22" side branches and had no luck. After re-doing my math and using some Audacity frequency analysis, I figured out that they had to be 27-28" to work at the RPM I wanted. Longer pipes tune out frequencies lower in the RPM range. Shorter pipes (increasingly less effective) hit the higher rpms. I had the mechanic fix the pipes to 28" and VOILA, absolutely zero drone from 2200rpms to 2800rpms. At 2000rpms there is a slight rumble in the cabin, but no drone. Same at 3000rpms which changes into an aggressive purr. Absolutely nothing changed about the exhaust sound or performance in any way besides the reduction (went from heavy drone that was very uncomfortable to NO DRONE) in drone. Plus, its all tucked up behind the bumper where the muffler used to be so you cant tell.
I hope this helps for those who hate the droning but want to keep the performance, sound and looks! I guarantee that it works amazingly, others on other car forums have had the same results when you use the right length of side branch resonators. If you dont mind the drone or dont want to cut into your gorgeous exhaust, enjoy as is.
Diagram is below and more info for those who want it, will have pics soon! Red and black are two pipes, each about 28" long total, capped at the end furthest from the connection to the OEM pipe. They meet the OEM pipes at 90 degrees and do not connect, they just pass each other on a side and are welded together for stability."
Edit.... Here's a post on another forum where the guy figured out how to get rid of his drone by adding an extension to his pipe. His isn't an F150 but the concept would apply to any vehicle with drone...
-------------------------------------------------------------------------------------------
"So I had the FI style exhaust and I agree its the deepest exhaust I've heard on a 370Z and sounds AMAZING, especially above 3000rpms. However, the downside is the drone between 2200-2800rpms was bad, worse for others depending on your tolerance, and was prevalent at cruising RPMS.
Being a mathy person, I figured I could fix the problem by hitting it at the source, what causes the drone. Drone is caused by the pipe resonance so to combat this, you need to use the exhaust wavelengths against themselves to cancel them out.
One way to do this is to put on a chambered muffler which breaks up the sound waves and avoids hitting the natural pipe resonance frequency. This also kills some performance because it hurts flow. This is how Corsa mufflers work as they are tuned per car to break up the frequency at which the exhaust system naturally resonates without affecting the flow. However they are very expensive and they dont make one for our car.
Standard resonators (Magnaflow, OEM, etc) are excellent at destroying high frequency resonance in the upper RPM ranges (3k plus) but dont do much for low frequency resonance (100khz-140khz). Changes in pipe size and tailpipe length can push the natural resonance frequency for the exhaust out of the normal RPM range but unfortunately with the FI style and most straight through exhausts I've seen on 370Z's, resonance happens from 2krps to 3krpms frequently and can be very annoying.
SO, finally the fix:
To get rid of drone (pipe resonance), you need to cancel out those specific pipe resonant frequencies. To do this without using a chambered muffler you can use whats called a Side Branch Resonator.
The side branch resonator is a pipe, around the same size as the exhaust pipe, which T's off the OEM pipe between the rearmost mufflers and the exhaust tips. For the FI style, it comes off at 90 degrees from that pipe and should go out straight across to the other side (in the area where the OEM hunker muffler was). One end is welded to the opening on the OEM pipe and the other end is welded shut with a cap, no filling in the pipe at all. The cap reflects the sound back into the OEM pipe. The length of the side branch pipes matters a LOT! To cancel out the frequencies you need to have them reflect back at a quarter wavelength from the side pipes that T off the main pipe. The simple answer is for the FI setup, if you have heavy resonance at 2500rpms (ish) then you need 28" side branch resonation pipes, one per side.
I did this on my car, first with 22" side branches and had no luck. After re-doing my math and using some Audacity frequency analysis, I figured out that they had to be 27-28" to work at the RPM I wanted. Longer pipes tune out frequencies lower in the RPM range. Shorter pipes (increasingly less effective) hit the higher rpms. I had the mechanic fix the pipes to 28" and VOILA, absolutely zero drone from 2200rpms to 2800rpms. At 2000rpms there is a slight rumble in the cabin, but no drone. Same at 3000rpms which changes into an aggressive purr. Absolutely nothing changed about the exhaust sound or performance in any way besides the reduction (went from heavy drone that was very uncomfortable to NO DRONE) in drone. Plus, its all tucked up behind the bumper where the muffler used to be so you cant tell.
I hope this helps for those who hate the droning but want to keep the performance, sound and looks! I guarantee that it works amazingly, others on other car forums have had the same results when you use the right length of side branch resonators. If you dont mind the drone or dont want to cut into your gorgeous exhaust, enjoy as is.
Diagram is below and more info for those who want it, will have pics soon! Red and black are two pipes, each about 28" long total, capped at the end furthest from the connection to the OEM pipe. They meet the OEM pipes at 90 degrees and do not connect, they just pass each other on a side and are welded together for stability."
01-15-2015, 11:15 AM
#16
Junior Member
Thread Starter
Thanks for all the help guy's!! Much appreciated! My ears are ringing as I write this. I noticed someone mentioned a dynomax bullet in place of the resonator. I heard this worked for another guy. I was thinking a 12" bullet in place of the old resonator. The shop kept my old one and it tamed my muffler down to near stock. So replacing it with a smaller one sounds like the way to go. The bullet says it will decrease 4db. Any thought's on the bullet or similar make? Thanks!
01-15-2015, 11:23 AM
#18
Junior Member
Thread Starter
Unfortunately getting loud exhaust and not having drone is hard to do. I did the same but kept my resonator and it's plenty loud enough for me. You can try putting on a longer muffler. I read a post on here the other day about a guy who put a glasspack in front of his muffler to act as a resonator and it sounded good. Let me see if I can find it and if I do I'll post it.
Here you go!
https://www.f150forum.com/f38/right-...inally-283126/
Here you go!
https://www.f150forum.com/f38/right-...inally-283126/
01-15-2015, 11:36 AM
#19
Senior Member
https://www.f150forum.com/f38/new-borla-muffler-226512/
my exp. with a muffler set that was too loud its just to my liking now!
my exp. with a muffler set that was too loud its just to my liking now!
01-15-2015, 09:45 PM
#20
Junior Member
Thread Starter
Do you guys think a 12" or 18" glasspack for my resonator? I want it to roar just no drone. Do you think a larger glasspack would kill my sound or just help with drone? I'm leaning towards the 12?