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Thread: I can hardly think with all this DRONE...

  1. #106
    Join Date
    Sep 2012
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    Raleigh, North Carolina
    Posts
    701
    Im a few dates late on this comment... dont get the Cherry Bomb Vortex mufflers. I had a dual 2.5" to a magnaflow res, to single 3", split into dual 3" and cherry bomb vortex mufflers out back. The drone was terrible.

    I used the pypes pro race muffler on my turbo v8 project and thought it sounded way better. it was a 3" in and out. of course the v8 is typically going to sound better anyways.

  2. #107
    Join Date
    Jul 2002
    Location
    Boston, MA
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    7,483
    Quote Originally Posted by dthompson View Post
    Im a few dates late on this comment... dont get the Cherry Bomb Vortex mufflers. I had a dual 2.5" to a magnaflow res, to single 3", split into dual 3" and cherry bomb vortex mufflers out back. The drone was terrible.

    I used the pypes pro race muffler on my turbo v8 project and thought it sounded way better. it was a 3" in and out. of course the v8 is typically going to sound better anyways.
    Thanks for the feedback. The Vortex does flow well, but glad you intercepted with your experience .

    Still on the fence waiting for the Borla credit before the next purchase. I can’t get myself to go chambered unless it’s a turbo design. And the space is limiting me for options.
    Last edited by ricardoa1; 01-16-2020 at 12:08 AM.

  3. #108
    Join Date
    Apr 2002
    Location
    St. Charles, MO
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    21,093
    Quote Originally Posted by ricardoa1 View Post
    I have room limitations. Unless I start cutting pasting.

    We want mufflers that will flow what the engine needs, no more. Since once at the point of no restriction any additional cfm doesnít increase HP but will affect the mufflers ability to work as a muffler.

    Our top dog motors are making 500whp, thatís what? 500*1.25 for 20% loss? Thatís 625 crank HP
    From an article
    600 hp on open exhaust will require 600 x 2.2 = 1,320 cfm. 2.2 being a straight pipe variable. Then Two 660-cfm mufflers will get the job done and contain the backpressureinduced power loss to 5 hp or less.

    Most SC donít make 500whp but itís reasonable to say gives you room for growth you want a 700CFM anything more is pointless and anything less you might start to lose HP if you are a top dog engine.

    Dynomax Super Turbos are advertised to flow 700 :/

    I got to see what the SW chambered does. They donít advertise it. But they confirmed the 3Ē in and out does go down to 2.5Ē internally and the louvres makes smaller. But if they flow 700 then why not.

    Pypes Street Flo and Magnaflow XL are 3 chamber mufflers where the inlet pipes end in the center chamber. But no sound deadening materials. So they might sound like a Flowmaster. IDK getting decision paralysis with this.
    Hi Ricardo,

    Probably want to add another 100 HP to that 625 HP for driving the supercharger. BTW, sounds like your mission to make me feel silly is going about how I expected. Several years ago me and DD had a lengthy discussion about what could or should be done to my super cool exhaust system to make it quieter at part throttle and get rid of the drone. Conclusion...Start over and build a new exhaust system.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  4. #109
    Join Date
    Jul 2002
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    Boston, MA
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    7,483
    Quote Originally Posted by David Neibert View Post
    Hi Ricardo,

    Probably want to add another 100 HP to that 625 HP for driving the supercharger. BTW, sounds like your mission to make me feel silly is going about how I expected. Several years ago me and DD had a lengthy discussion about what could or should be done to my super cool exhaust system to make it quieter at part throttle and get rid of the drone. Conclusion...Start over and build a new exhaust system.

    David
    Not giving up just yet, there is still Helmholtz tube idea and keep these magnaflows. For now I’m giving it a break.
    Last edited by ricardoa1; 01-16-2020 at 03:07 PM.

  5. #110
    Join Date
    Dec 2002
    Location
    Wintersville, OH
    Posts
    4,107
    Why did you buy this exhaust lol
    Making woosh sounds since 2010!

  6. #111
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    Jul 2002
    Location
    Boston, MA
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    Quote Originally Posted by neverfastenough View Post
    Why did you buy this exhaust lol
    I got it for a song. :P it looks and performs as expected, Neibert and Dalke didnít hide that it was loud. And I like the WOT sounds, Dalke suggested a new resonator when I picked up. I was well aware of the consequences, but I didnít think I was going to be so limited on choices of mufflers, and thatís really all this thing needs to make it not drone, that or change the frequency. The VT mufflers would have done wonders but I missed that boat or maybe it was a good thing IDK. I feel hot rodding is losing its luster and market cause there were a few more choices 10 years ago.

  7. #112
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    Jul 2002
    Location
    Boston, MA
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    From another website/forum:


    ďThe concept behind drone is pretty simple; nearly everything has a resonant frequency...exhaust systems, electronic RLC circuits, even gravitation has resonance. At peak resonance, the amplitude of the wave at the resonant frequency shoots up to many times higher than normal amplitude. With sound resonance, it pops up when a certain frequency emitted from the engine resonates with the exhaust system and muffler to create that nasty in-cab drone. Unfortunately this resonance often has its peak right in the area where you want to cruise, between 55-75mph.

    The solution is a 1/4 wave resonator tube. Simply put, it is a small piece of exhaust pipe with a flat capped end welded nearly perpendicular to the exhaust flow post-muffler that serves to take some of the resonant amplitude and shoot it back into the exhaust pipe out of phase with the resonant frequency to bring down the amplitude. If you've ever taken a physics class, this is in the 'standing wave dynamics' chapter. Mufflers are designed to bring down the amplitude or volume of the exhaust note at all RPMs, but they typically can't do anything about resonance.

    Things you need to know to build the resonator: (Super Coupe)

    -RPM that drone occurs at
    -Number of cylinders (6)

    You will also need to know the speed of sound. It varies with temperature, but is generally accepted to be 343m/s.

    Say your Super Coupe resonates at 1,800rpms, right at cruising speed. You'll need to find the frequency of the drone. Units here are pulses per second, or Hertz.

    f = RPM * pulses/rev * (1/60)

    f = 1800 rev/min for an SC * 3 pulses/rev for an SC * (1/60) RPMins to RPSeconds

    f = 90 pulses/second = 90Hz

    At 1,800rpms, your SCV6 fires 3 times per revolution. RPM is in minutes, so divide by 60 to reduce to seconds. Now you need to find the length of the wave at the frequency you just calculated. Wavelength is denoted by lambda (λ), units are meters.

    λ = v/f = speed of sound / frequency

    λ = (343m/s)/(90Hz)

    λ = 3.8 meters NICE!

    This gives you the length of a full sound wave. The idea here is to reintroduce a sound wave into the exhaust that is 180į out of phase with your drone frequency. To do this, you build your resonator tube at exactly one-fourth the length of the resonant wave. By the time the sound wave enters the resonator tube, bounces off the end and re-enters the exhaust stream, the amplitude is exactly opposite of the drone frequency and will lower or eliminate the volume of the drone.

    Dividing the wavelength by 4 gives you 0.95m, or about 3.2 feet.

    The diameter of the tube you'd need is debatable, I assume a larger resonator tube would allow more sound to bounce back and cancel more of the drone noise. However, space is somewhat limited when you are sending an exhaust pipe off of your existing pipe at some odd angle. You can bend the resonator tube to some extent, but it needs to be mandrel bent, not more than one bend or more than ~30į. If the bend is too sharp, the sound will bounce back too early and the resonator will work poorly or won't work at all.

    The reason for this is simply the fact that sound waves do not necessarily 'flow' with whatever medium they are travelling in. Sound is a pressure wave, and any obstacle (bends) will return the wave prematurely. To minimize 'obstacles' in the resonator tube, the straighter it is, the better it will work. The intent is not to randomly scatter the sound wave as a radius will tend to do, but to send it back to the exhaust precisely when it is needed.

    As you can see I replaced its original variables with SC variables, where I am still confused is the above is for a single exhaust, when using on a dual exhaust do we then split the 3.2 feet into two? 1.6 feet?

  8. #113
    Join Date
    Sep 2012
    Location
    Raleigh, North Carolina
    Posts
    701
    Quote Originally Posted by ricardoa1 View Post
    From another website/forum:


    ďThe concept behind drone is pretty simple; nearly everything has a resonant frequency...exhaust systems, electronic RLC circuits, even gravitation has resonance. At peak resonance, the amplitude of the wave at the resonant frequency shoots up to many times higher than normal amplitude. With sound resonance, it pops up when a certain frequency emitted from the engine resonates with the exhaust system and muffler to create that nasty in-cab drone. Unfortunately this resonance often has its peak right in the area where you want to cruise, between 55-75mph.

    The solution is a 1/4 wave resonator tube. Simply put, it is a small piece of exhaust pipe with a flat capped end welded nearly perpendicular to the exhaust flow post-muffler that serves to take some of the resonant amplitude and shoot it back into the exhaust pipe out of phase with the resonant frequency to bring down the amplitude. If you've ever taken a physics class, this is in the 'standing wave dynamics' chapter. Mufflers are designed to bring down the amplitude or volume of the exhaust note at all RPMs, but they typically can't do anything about resonance.

    Things you need to know to build the resonator: (Super Coupe)

    -RPM that drone occurs at
    -Number of cylinders (6)

    You will also need to know the speed of sound. It varies with temperature, but is generally accepted to be 343m/s.

    Say your Super Coupe resonates at 1,800rpms, right at cruising speed. You'll need to find the frequency of the drone. Units here are pulses per second, or Hertz.

    f = RPM * pulses/rev * (1/60)

    f = 1800 rev/min for an SC * 3 pulses/rev for an SC * (1/60) RPMins to RPSeconds

    f = 90 pulses/second = 90Hz

    At 1,800rpms, your SCV6 fires 3 times per revolution. RPM is in minutes, so divide by 60 to reduce to seconds. Now you need to find the length of the wave at the frequency you just calculated. Wavelength is denoted by lambda (λ), units are meters.

    λ = v/f = speed of sound / frequency

    λ = (343m/s)/(90Hz)

    λ = 3.8 meters NICE!

    This gives you the length of a full sound wave. The idea here is to reintroduce a sound wave into the exhaust that is 180į out of phase with your drone frequency. To do this, you build your resonator tube at exactly one-fourth the length of the resonant wave. By the time the sound wave enters the resonator tube, bounces off the end and re-enters the exhaust stream, the amplitude is exactly opposite of the drone frequency and will lower or eliminate the volume of the drone.

    Dividing the wavelength by 4 gives you 0.95m, or about 3.2 feet.

    The diameter of the tube you'd need is debatable, I assume a larger resonator tube would allow more sound to bounce back and cancel more of the drone noise. However, space is somewhat limited when you are sending an exhaust pipe off of your existing pipe at some odd angle. You can bend the resonator tube to some extent, but it needs to be mandrel bent, not more than one bend or more than ~30į. If the bend is too sharp, the sound will bounce back too early and the resonator will work poorly or won't work at all.

    The reason for this is simply the fact that sound waves do not necessarily 'flow' with whatever medium they are travelling in. Sound is a pressure wave, and any obstacle (bends) will return the wave prematurely. To minimize 'obstacles' in the resonator tube, the straighter it is, the better it will work. The intent is not to randomly scatter the sound wave as a radius will tend to do, but to send it back to the exhaust precisely when it is needed.

    As you can see I replaced its original variables with SC variables, where I am still confused is the above is for a single exhaust, when using on a dual exhaust do we then split the 3.2 feet into two? 1.6 feet?

    Ive thought about this a lot with those vortex mufflers. I never got around to doing it, but I concluded that the best solution was to make the tube length adjustable. Guess and test, then figure out the length that works and then weld it up solid.

  9. #114
    Join Date
    Jul 2002
    Location
    Boston, MA
    Posts
    7,483
    I think I am back on the mission. Carefully reading through part numbers and descriptions. I was able figure out a Stainless Works offering that will be turbo chambered like the Dynomax, and be 3” on the inside triple core pipes. I had to move away from center in configuration to both offset and opposite, in that they have the space to install the 3” through out. I feel the center configuration is why the one Chris and I needed is limited to 2.5” so air can cross over and under the center pipe. But the case being 5” it becomes a problem.

    Anyways, full MSRP on this one and I’ll need to possibly modify the axle pipes to give me the angle to do the tail pipes.

    Stainless Works.
    TM5C3O3OPS
    3" ID OFFSET INLET/ 3" OD OFFSET OUTLET, 3.000" DIA CORE, 5 x 9 x 14" SHELL 304 SS CHAMBERED TURBO MUFF

  10. #115
    Join Date
    Jul 2002
    Location
    Boston, MA
    Posts
    7,483
    Situation is hilarious, I got the call from Jegs only to be disappointed to know stainless works discontinued the above mentioned part number. I called Summit and they were holding on to the last set in their inventory. Challenge remains we will see how it goes when the unicorn arrives.

  11. #116
    Join Date
    Oct 2003
    Location
    Allentown, PA
    Posts
    949
    Video for Helmholtz Resonator: https://www.youtube.com/watch?v=ekJy78e9QIk

    This place sells them: http://synapseengineering.com/synaps...s/nodrone.html
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    It appears if you have a dual exhaust you will need two:
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    J.Miller
    1990 XR7 and 1955 F250!

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