Drone Resonance and more Droning Thread
#31
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Originally Posted by SoCalM5Mang' post='506796' date='Dec 14 2007, 01:56 PM
Couple of last questions:
___Piping---I'm assuming I should try and stick to stock size piping as much as possible to minimize/prevent low end torque loss? (double pipe areas (between the two resonators) is about 2.25" diameter and in the single pipe areas (between the box resonator and the rear muffler) is about 2.9"-3.1" diameter.
___Rear Mufflers---I want to use the Dynomax Super Turbo Muffler due to its chambered technology. Would using this Chambered design hurt low end torque versus a Magnaflow Turbo that is straight thru?
Thanks guys!
So Cal
___Piping---I'm assuming I should try and stick to stock size piping as much as possible to minimize/prevent low end torque loss? (double pipe areas (between the two resonators) is about 2.25" diameter and in the single pipe areas (between the box resonator and the rear muffler) is about 2.9"-3.1" diameter.
___Rear Mufflers---I want to use the Dynomax Super Turbo Muffler due to its chambered technology. Would using this Chambered design hurt low end torque versus a Magnaflow Turbo that is straight thru?
Thanks guys!
So Cal
Rear mufflers : Chambered is old school, we don't use it, it restricts performance, a well packaged straight through muffler will do the job.
#32
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Originally Posted by SoCalM5Mang' post='506511' date='Dec 13 2007, 06:00 PM
Hi Quy!
Thanks for your help. I wanted to re-hash what we just described as the two potential options for Triple AAA tomorrow?
Two Options:
___AlexF's set up with Center Muffler and Two Rears(paraphrasing Rody?s suggestion from the thread below)(the two Rears being Turbo 4x9 Dynomax-center inlet and side outlet on both sides to uniformly fit best with least hang)
If they are willing to do a center mounted muffler (replacing the center box resonator) then I would go with a Remus because there is less chance of droning. Ideally a 545/550 Remus mounted in that location and split into two straight pipes to the tips would be best. But I don't know if the 545/550 Remus would fit there or not. Looking at AlexFW's picture (which I am reposting here) the space there looks bigger than I had imagined. The oval can that he has mounted there looks similar in size to the Remus 545/550 exhaust.....and that's at the front end, the space looks even wider towards the end of the center section. I bet AAA can make a Remus 545/550 muffler fit where the oem box resonator sits....which is where Alex has put the two double round resonators in this picture.
___Your Set-Up as we discussed: (what I'm 90% likely to do)
From the headers, keep the 2 stock resonators where they are. After them, cut the pipe and add an x-pipe. After the x-pipe, cut (both ends) of the OE boxed resonator and weld it after the x-pipe. Going out of the OE boxed resonator (it's actually 2 straight pipes inside) will be 2 custom piping, each going to each side of the car. Install 4x9 Super Turbo Dynomax (center inlet with side outlet on both left and right side and weld to my custom ACS tips
Does the size of the piping matter with either set-up?
Thanks Guys!
Jay C
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Originally Posted by rodybmw' post='506531' date='Dec 13 2007, 06:42 PM
...........
Does anyone know if it matters what order each component goes in? What I mean is that in the oem setup the resonators always come before the muffler.....would it be OK to have it the other way around with the muffler in the middle and the resonators coming AFTER the muffler? So the complete setup being the two tube resonators up front, then a muffler in place of the box resonator in the middle, and then another set of tube resonators at the rear?
Does anyone know if it matters what order each component goes in? What I mean is that in the oem setup the resonators always come before the muffler.....would it be OK to have it the other way around with the muffler in the middle and the resonators coming AFTER the muffler? So the complete setup being the two tube resonators up front, then a muffler in place of the box resonator in the middle, and then another set of tube resonators at the rear?
Most auto tubo muffler are both reactive (chamber) and have fiberglass and/or ss wool as absorptive material. So what frequencies are left, the "tuned" resonator take care. On a car, manufacturer use resonators first because:
1. size and space limitation
2. straight design gives engine more volume before it hits the chambered muffler
3. more room in the back for mufflers
4. For cars without resonators, the equation for tailpipe length to not generate more niose need not be a concern when muffler is at rear.
As for 5er, as long as your mid muffler are straight through design, you should be OK.
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Originally Posted by RemusExhaustShop' post='506827' date='Dec 14 2007, 02:28 PM
Piping : That would be correct.
Rear mufflers : Chambered is old school, we don't use it, it restricts performance, a well packaged straight through muffler will do the job.
Rear mufflers : Chambered is old school, we don't use it, it restricts performance, a well packaged straight through muffler will do the job.
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#35
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Originally Posted by vegastrashed' post='506464' date='Dec 13 2007, 03:19 PM
Bimmer32,
You have become quite the resident e60.net exhaust expert.
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You have become quite the resident e60.net exhaust expert.
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This is not the old B32 . . . he got slaughtered by the wife after the exhaust mod was too loud. The new B32 promise not to let another member make the same potential mistake.
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Exhaust engineering is quite interesting. I got a lot of info. from some of the design-build MEP (mechanical eletrical plumbing) engineers I know plus weeks on end resourcing the web and a book.
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#36
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Engine: Custom AFE CAI, Superchips ECU remap, Sprint Booster, RDSport Dual Exhaust Conversion with Quad Pipes and X-pipe, 3 resonators deleted, 90mm tips!
Exterior: M-Tech Aero kit | M5 Mirrors | M5 Rear Bumper | Trunk Lid Finisher | Vorsteiner decklid spoiler | 50% Formula One Pinnacle Tint
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Originally Posted by Bimmer32' post='496341' date='Nov 19 2007, 08:08 AM
Attack of the droning . . .
The sound is sweet, and the sound level above 2K rpm is about 5 db above the stock sound. BUT, during deceleration (no engine load) or acceleration (straining engine load) around 1500 to 2000 rpm and idle at 750 rpm, the exhaust pressure isn't strong enough to push the air particles fast enough out of the exhaust system. Hence, the "sound waves" bombard the walls of the piping and thereby cause DRONING or resonance. Apparently, my search on other V8 forums identified that this is a "popular" problem with V8s. Additionally, idle sound is notably louder at 750 rpm versus 500 rpm.
The sound is sweet, and the sound level above 2K rpm is about 5 db above the stock sound. BUT, during deceleration (no engine load) or acceleration (straining engine load) around 1500 to 2000 rpm and idle at 750 rpm, the exhaust pressure isn't strong enough to push the air particles fast enough out of the exhaust system. Hence, the "sound waves" bombard the walls of the piping and thereby cause DRONING or resonance. Apparently, my search on other V8 forums identified that this is a "popular" problem with V8s. Additionally, idle sound is notably louder at 750 rpm versus 500 rpm.
#37
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My Ride: 2007 E63 AMG | Obsidian Black | Schwarzes Nappa | Black BirdEye Maple | Premium II Package | Electronic Trunk Closer | Parktronic
Engine: RPi/Powerchips custom ECU tune, RPi Ram Air Kit (BMC filter, scoops), RennTech Sport exhaust, secondary cats, charcoal and resonator delete, custom AAA x-pipe
Exterior: 50% side windows / 35% rear window Formula One Pinnacle Series | Flat AMG hood emblem
Suspension: Renntech Lowering Module
Wheels/Tires: Radenergie R10, Falken FK452 245/30/20, Yokohama ADVAN Sport 285/25/20
-----------------------------------------
2005 545i Sport SMG | Ti Grau | Schwarzes Dakota | Anthracite Maple | Logic 7 | Nav
Engine: Custom AFE CAI, Superchips ECU remap, Sprint Booster, RDSport Dual Exhaust Conversion with Quad Pipes and X-pipe, 3 resonators deleted, 90mm tips!
Exterior: M-Tech Aero kit | M5 Mirrors | M5 Rear Bumper | Trunk Lid Finisher | Vorsteiner decklid spoiler | 50% Formula One Pinnacle Tint
Suspension and Brakes: Bilstein PSS9 coilovers, JBT BBK: 16" cross-drilled rotors, 8 piston and 15" cross-drilled rotors, 4 piston
Wheels: VIP Modular VR 02 20x9F, 20x10R | Toyo T1R 245/30/20F, 285/25/20R
Lights: PIAA 4150K Xtreme White Plus fog lights, AIB v3
MOST IMPORTANT: Hardwired V1; =)
ED Date: 4/7/05, Re-delivery date: 5/21/05
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This was initially a double post but I'll just mention that I think that the design/engineering that went into the RDSport exhaust is better than the Renntech exhaust. To me, the Renntech sounds like a louder and deeper version of the stock AMG exhaust, which I am not a fan of. The AMG exhaust sounds too much like American muscle with straight pipes, not the refined V8 note that I like. It would appear that it's not recommended to remove the resonator if choosing the Renntech. As I type, the likelihood of the resonator going back on is 75%. I'll see what others will have to say about the exhaust at the Socal Meet on Saturday.
#38
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Originally Posted by vegastrashed' post='507020' date='Dec 15 2007, 02:06 AM
On my E63, I just recently got a Renntech exhaust put in, removal of the secondary cats/stock crossover and resonator replaced with x-pipe, and stock air filter replaced with AFE air filter. I'm encountering the droning problem that Bimmer32 mentions which I've highlighted in red. Between 1500 and 2000 rpm, the droning is very prevalent but at over 2500 - 7000 rpm, it's music to my ears. I'm think of putting back the resonator to remove the droning. For those who are thinking did the x-pipe help with the droning, yes it did. Before the x-pipe was installed the droning was loud. Now, with the x-pipe installed, it reduced but didn't eliminate the droning. Also, the x-pipe gave me the exhaust tone/pitch I've been wanting. It now sounds like my 545i with the RDSport quad exhaust except it's much louder and of course the droning.
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#39
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My Ride: 2007 E63 AMG | Obsidian Black | Schwarzes Nappa | Black BirdEye Maple | Premium II Package | Electronic Trunk Closer | Parktronic
Engine: RPi/Powerchips custom ECU tune, RPi Ram Air Kit (BMC filter, scoops), RennTech Sport exhaust, secondary cats, charcoal and resonator delete, custom AAA x-pipe
Exterior: 50% side windows / 35% rear window Formula One Pinnacle Series | Flat AMG hood emblem
Suspension: Renntech Lowering Module
Wheels/Tires: Radenergie R10, Falken FK452 245/30/20, Yokohama ADVAN Sport 285/25/20
-----------------------------------------
2005 545i Sport SMG | Ti Grau | Schwarzes Dakota | Anthracite Maple | Logic 7 | Nav
Engine: Custom AFE CAI, Superchips ECU remap, Sprint Booster, RDSport Dual Exhaust Conversion with Quad Pipes and X-pipe, 3 resonators deleted, 90mm tips!
Exterior: M-Tech Aero kit | M5 Mirrors | M5 Rear Bumper | Trunk Lid Finisher | Vorsteiner decklid spoiler | 50% Formula One Pinnacle Tint
Suspension and Brakes: Bilstein PSS9 coilovers, JBT BBK: 16" cross-drilled rotors, 8 piston and 15" cross-drilled rotors, 4 piston
Wheels: VIP Modular VR 02 20x9F, 20x10R | Toyo T1R 245/30/20F, 285/25/20R
Lights: PIAA 4150K Xtreme White Plus fog lights, AIB v3
MOST IMPORTANT: Hardwired V1; =)
ED Date: 4/7/05, Re-delivery date: 5/21/05
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I should be asleep but the droning issue has consumed me. I've gone through many car forums and somehow came across the Dynatech Vortex Insert Cone. You can read up on what a CTS owner did here with the cone. If you google "Dynatech Vortex" there's a lot of examples in the Mustang, Nissan Titan, and other forums. So, what do you think B32 and rody about this Vortex insert cone as a resonance neutralizer?
The Vortex Insert Cone, installed near the exit of the header collector or muffler outlet, provides a large friction area to reflect and dissipate sound energy, thus reducing the dB level. Because no significant backpressure has been introduced, the engine is still able to use the scavenge ability of a good header to create horsepower and torque. Dyno and track testing show significant noise reduction with little or no power loss.