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      02-01-2020, 09:14 PM   #23
3002 tii
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Any update to this? I too am missing the exotic tone from the Powerloops and may go back to them lol.
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      02-01-2020, 09:25 PM   #24
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Living with the drone around 1-2k, it's not as terrible as before, I think due to not overtightening the hangers but this is just speculation. I'm enjoying the tone especially during 3-5k rpm pulls where the bass + treble notes are balanced. I think it could afford to be louder > 4k rpm. Sometimes I wish I had a valved exhaust that I could use to switch to something more like supersprint race. Only for high rpms and when i'm in the mood hah.

I kind of miss hearing my aFe intake. It was more audible when I had the remus. I can still hear it but only if I stomp on the throttle. But I don't think I'm going back to remus, the powerloops are more exciting.

Last edited by filtercoffee; 02-01-2020 at 09:32 PM..
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      02-01-2020, 09:31 PM   #25
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I think if I had to do it all over again I would've started with modding the oem mufflers e.g.
https://www.zpost.com/forums/showthread.php?t=1398616

Seems like you'd get some of the bass cancellation of the oem mufflers and more high-frequency scream at high RPM. The oem muffler design seems pretty high-flow. Perhaps even more so than powerloops since the powerloops have a couple of 180 degree turns.
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      02-11-2020, 12:09 AM   #26
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Just occurred to me but have you thought of installing a “reducer” similar to the RPi silencers? I think the tips on the Powerloops are 80mm but they’re not perfectly circular. On the shortest diameter it’s probably close to 70mm, so something like this may work:

http://www.everyexhaustpart.com/cart...expander.htmlQ

You basically need to drill a small hole underneath and secure the reducer with a nut and bolt:

https://www.raceprecision.com/product/RPI-RP-023.html
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      02-11-2020, 12:16 AM   #27
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Nah, I don't want to drill into those beautiful tips, plus getting the fit right seems like it'd be next to impossible due to the curvature of the inside of the tip. Btw, how does that even work to reduce the sound level?

The drone is only annoying at 2k rpm ish and then I actually think the powerloops could afford to be louder higher than that :P. Pretty satisfied with the exhaust setup right now.
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      02-12-2020, 09:36 AM   #28
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I feel like it's impossible to go loud without massive drone on this platform.

I have a roadster w/ catless headers and stromungs mufflers (everything else in exhaust is stock) and with the top closed it drones bad (very bassy). Top down all drone is gone. Wanna go louder so bad but top closed drone will be unbearable. Some sort of valved system/muffler may be the only option but I haven't seen any good examples of this.

For reference to drone tolerance I run a non resonated Remus catback with valves open all the time in my f80 m3 and don't mind it
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      02-13-2020, 07:19 PM   #29
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Quote:
Originally Posted by ryank382 View Post
I feel like it's impossible to go loud without massive drone on this platform.

I have a roadster w/ catless headers and stromungs mufflers (everything else in exhaust is stock) and with the top closed it drones bad (very bassy). Top down all drone is gone. Wanna go louder so bad but top closed drone will be unbearable. Some sort of valved system/muffler may be the only option but I haven't seen any good examples of this.

For reference to drone tolerance I run a non resonated Remus catback with valves open all the time in my f80 m3 and don't mind it
Welding these in between the x pipe and muffler flange may do the trick. Just need to measure if 2.25 or 2.5” is better fit but they’re nice and short so squeezing in should not be problem

https://www.totalflowusa.com/totalfl...l-race-muffler
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      02-13-2020, 07:51 PM   #30
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Quote:
Originally Posted by ZeD4Mr View Post
Quote:
Originally Posted by ryank382 View Post
I feel like it's impossible to go loud without massive drone on this platform.

I have a roadster w/ catless headers and stromungs mufflers (everything else in exhaust is stock) and with the top closed it drones bad (very bassy). Top down all drone is gone. Wanna go louder so bad but top closed drone will be unbearable. Some sort of valved system/muffler may be the only option but I haven't seen any good examples of this.

For reference to drone tolerance I run a non resonated Remus catback with valves open all the time in my f80 m3 and don't mind it
If there's room, welding in a J pipe like this. This is loud but no drone.
Weld in a J Pipe like this. Loud and no drone.
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      02-14-2020, 09:27 AM   #31
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Quote:
Originally Posted by 3002 tii View Post
Quote:
Originally Posted by ryank382 View Post
I feel like it's impossible to go loud without massive drone on this platform.

I have a roadster w/ catless headers and stromungs mufflers (everything else in exhaust is stock) and with the top closed it drones bad (very bassy). Top down all drone is gone. Wanna go louder so bad but top closed drone will be unbearable. Some sort of valved system/muffler may be the only option but I haven't seen any good examples of this.

For reference to drone tolerance I run a non resonated Remus catback with valves open all the time in my f80 m3 and don't mind it
Welding these in between the x pipe and muffler flange may do the trick. Just need to measure if 2.25 or 2.5" is better fit but they're nice and short so squeezing in should not be problem

https://www.totalflowusa.com/totalfl...l-race-muffler
Thanks for the reply man I considered something like this but I just feel like a small resonator won't do the trick but then again I'm not sure.

Quote:
Originally Posted by ZeD4Mr View Post
Quote:
Originally Posted by ZeD4Mr View Post
Quote:
Originally Posted by ryank382 View Post
I feel like it's impossible to go loud without massive drone on this platform.

I have a roadster w/ catless headers and stromungs mufflers (everything else in exhaust is stock) and with the top closed it drones bad (very bassy). Top down all drone is gone. Wanna go louder so bad but top closed drone will be unbearable. Some sort of valved system/muffler may be the only option but I haven't seen any good examples of this.

For reference to drone tolerance I run a non resonated Remus catback with valves open all the time in my f80 m3 and don't mind it
If there's room, welding in a J pipe like this. This is loud but no drone.
Weld in a J Pipe like this. Loud and no drone.

Thank you for the recommendation. I haven't read much about using a J pipe but after doing a quick search seems like it helps a lot of people. Will have to find an exhaust shop by me (fort lee nj) and try this. Do you know if you need a specific length to cancel out the right frequency? Seems like some people weld these on before the mufflers but not sure what the best application is on our platform or with a specific muffler like my stromungs lol

Sorry for thread jacking!!
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      02-14-2020, 12:20 PM   #32
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Originally Posted by ryank382 View Post
Thanks for the reply man I considered something like this but I just feel like a small resonator won't do the trick but then again I'm not sure.


Thank you for the recommendation. I haven't read much about using a J pipe but after doing a quick search seems like it helps a lot of people. Will have to find an exhaust shop by me (fort lee nj) and try this. Do you know if you need a specific length to cancel out the right frequency? Seems like some people weld these on before the mufflers but not sure what the best application is on our platform or with a specific muffler like my stromungs lol

Sorry for thread jacking!!
Seems to me doing it along the x pipe (right before the muffler) would be most effective but maybe that person installed onto muffler due to spacing reasons.
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      02-14-2020, 03:02 PM   #33
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Quote:
Originally Posted by ryank382 View Post
Do you know if you need a specific length to cancel out the right frequency?
Yes. A J-pipe works by phase-cancellation. Part of the sound from the engine enters the J-pipe and is reflected back with a time delay proportional to the length of the J-pipe. When the reflected sound is exactly half a wavelength delayed compared to the origin sound wave, the peaks and valleys cancel each other out.

In order for the reflected sound wave to be 1/2 a wavelength delayed, the J-pipe must be 1/4 of a wavelength long. The sound will travel to the end of the J-pipe and back, 1/4 + 1/4 = 1/2. To calculate the optimal length of the J-pipe:

1. Identify the frequency you want to cancel out, using a sound meter app.
2. Calculate the wavelength of that frequency. Wavelength = How far the sound wave propagates in one wave cycle = speed of sound divided by frequency. Note that the speed of sound is temperature dependent.
3. Build a J-Pipe 1/4 the wavelength.

For example, to cancel out 90hz, assuming you want to cancel it when the exhaust is hot (I don't know, 500 F?), the speed of sound is 460 m/s (calculator), the wavelength is 460/90 = 5.1 meters, a quarter wave is 1.25 meters! however, the air in the J-pipe may actually be cooler that the exhaust gas since exhaust gas doesn't flow through it. If we use 100 F, the speed of sound is 353.4 m/s, a quarter-wave is 1 meter, which is still a very long J-pipe.

I suspect the J-pipe in the muffler above goes deep into the muffler and maybe does a bend. It's also possible that the muffler itself does a better job of cancelling low-frequencies than the stromung due to a different internal design. It's also possible that you don't need to get the optimal length in order to reduce the drone sufficiently.

Ultimately trial and error is a simple and guaranteed way to get to the results you want. Depending on how much time and money you want to spend, you might be better off modding the OEM muffler because you'd get the good low-frequency cancellation it provides.
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      02-14-2020, 03:53 PM   #34
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Quote:
Originally Posted by ZeD4Mr View Post
Quote:
Originally Posted by filtercoffee View Post
Quote:
Originally Posted by ryank382 View Post
Do you know if you need a specific length to cancel out the right frequency?
Yes. A J-pipe works by phase-cancellation. Part of the sound from the engine enters the J-pipe and is reflected back with a time delay proportional to the length of the J-pipe. When the reflected sound is exactly half a wavelength delayed compared to the origin sound wave, the peaks and valleys cancel each other out.

In order for the reflected sound wave to be 1/2 a wavelength delayed, the J-pipe must be 1/4 of a wavelength long. The sound will travel to the end of the J-pipe and back, 1/4 + 1/4 = 1/2. To calculate the optimal length of the J-pipe:

1. Identify the frequency you want to cancel out, using a sound meter app.
2. Calculate the wavelength of that frequency. Wavelength = How far the sound wave propagates in one wave cycle = speed of sound divided by frequency. Note that the speed of sound is temperature dependent.
3. Build a J-Pipe 1/4 the wavelength.

For example, to cancel out 90hz, assuming you want to cancel it when the exhaust is hot (I don't know, 500 F?), the speed of sound is 460 m/s (calculator), the wavelength is 460/90 = 5.1 meters, a quarter wave is 1.25 meters! however, the air in the J-pipe may actually be cooler that the exhaust gas since exhaust gas doesn't flow through it. If we use 100 F, the speed of sound is 353.4 m/s, a quarter-wave is 1 meter, which is still a very long J-pipe.

I suspect the J-pipe in the muffler above goes deep into the muffler and maybe does a bend. It's also possible that the muffler itself does a better job of cancelling low-frequencies than the stromung due to a different internal design. It's also possible that you don't need to get the optimal length in order to reduce the drone sufficiently.

Ultimately trial and error is a simple and guaranteed way to get to the results you want. Depending on how much time and money you want to spend, you might be better off modding the OEM muffler because you'd get the good low-frequency cancellation it provides.
My shop also did a "Ginger" Rpi for the Z4M. Use a resonator at the end of a J-pipe. Just gloriously loud without the drone.
I think it's a Vibrant
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      02-14-2020, 04:16 PM   #35
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Video + sound please!!!
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      02-15-2020, 05:39 PM   #36
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Video + sound please!!!
Ended up rebuying Powerloops lol. Now we can do this comparison in person lol.
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      02-17-2020, 09:11 AM   #37
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Quote:
Originally Posted by filtercoffee View Post
Quote:
Originally Posted by ryank382 View Post
Do you know if you need a specific length to cancel out the right frequency?
Yes. A J-pipe works by phase-cancellation. Part of the sound from the engine enters the J-pipe and is reflected back with a time delay proportional to the length of the J-pipe. When the reflected sound is exactly half a wavelength delayed compared to the origin sound wave, the peaks and valleys cancel each other out.

In order for the reflected sound wave to be 1/2 a wavelength delayed, the J-pipe must be 1/4 of a wavelength long. The sound will travel to the end of the J-pipe and back, 1/4 + 1/4 = 1/2. To calculate the optimal length of the J-pipe:

1. Identify the frequency you want to cancel out, using a sound meter app.
2. Calculate the wavelength of that frequency. Wavelength = How far the sound wave propagates in one wave cycle = speed of sound divided by frequency. Note that the speed of sound is temperature dependent.
3. Build a J-Pipe 1/4 the wavelength.

For example, to cancel out 90hz, assuming you want to cancel it when the exhaust is hot (I don't know, 500 F?), the speed of sound is 460 m/s (calculator), the wavelength is 460/90 = 5.1 meters, a quarter wave is 1.25 meters! however, the air in the J-pipe may actually be cooler that the exhaust gas since exhaust gas doesn't flow through it. If we use 100 F, the speed of sound is 353.4 m/s, a quarter-wave is 1 meter, which is still a very long J-pipe.

I suspect the J-pipe in the muffler above goes deep into the muffler and maybe does a bend. It's also possible that the muffler itself does a better job of cancelling low-frequencies than the stromung due to a different internal design. It's also possible that you don't need to get the optimal length in order to reduce the drone sufficiently.

Ultimately trial and error is a simple and guaranteed way to get to the results you want. Depending on how much time and money you want to spend, you might be better off modding the OEM muffler because you'd get the good low-frequency cancellation it provides.
Awesome thank you for the detailed explanation! Much appreciated
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