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Mad Muffler Mod
We cut the top off of our muffler yesterday, a piece nearly three feet long and maybe six inches wide. About five spot welds down the length of the center had to be drilled, welds used to secure the muffler skin to separate walls and supports. The long cut was made just inside two other parallel rows of spot welds to avoid the extra trouble.
Inside, the muffler looked like a pipe organ, four or five pipes of varying lengths in parallel, each pipe slightly more than 1.5 inches id. Some pipes were short, one maybe six inches, another perhaps a foot long. A longer one below. These pipes are the only way for exhaust pressure to move between most of the walls, though some walls had a round opening or two. It seems one wall near the intake pipe was made of grate or large mesh. There were two long pipes leading to the outlets. These pipes were solid for the first third, then perforated, six holes around, about 3/16" diameter. These holes were spaced every 2.5 inchs down the rest of the length. To exit, the exhaust pressure has to find the open pipe at the far end and travel the length of the muffler and out the tip, and/or be forced through the small holes into the pipe and out the tip. The long pipes make the exhaust path nearly three feet longer than it would appear by the looking at the exhaust tips. The holes may just dampen the sound by allowing the pressure pulses to travel in and out of the pipe. This muffler is an impressive work of art. Nothing cheap about the design or build. I really hated to hack it up, but that's what extra parts are for! Only the long pipes going to the outlets were hacked, cutting out six inch sections between the walls. The exhaust pressure must still pass through two or three holes in the inner walls. The 'tuning' pipes designed to move exhaust pressure between two or three sections over were left alone. A piece was fabricated and then welded back on top of the muffler. One of our friends is a master with metal, otherwise this probably would not have been attempted. Two to three hours for the project. Once the trans is installed and everything is put back together, we'll let everyone know what we think of the sound. This is a California car and all three cats are intact. The resonator was replaced by straight pipe before the car found a home here. The mad-mod should make more sound but probably not any difference in power. This is still not a flow through design and the stock exits are still in place. Essentially, the muffler was converted to a multi-chamber system from some variant of a non-flow-through perforated-tube system. So, whatever that means?!
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Special Thanks to Our Friends and Sponsors: * http://www.alcyone.org.uk/ssm http://www.PhenixWheels.com http://www.dba.com.au/ http://www.ClassicSoftTrim.com http://ToyoTires.com/tire/pattern/versado-lx Gillman Subaru of Houston "QuickChange" http://www.TransGo.com/ http://www.PlanetSVX.com Bontrager Works, '92 Subaru SVX LS-L Claret ORIGINAL OWNER '92 LS-L Pearl~ '92 LS Pearl~ '92 LS-L Teal~ '92 LS-L Silver~ '95 LSi Polo~ '92 JDM Alcyone SVX Version-L 4WS Pearl~ http://www.subaru-svx.net/forum/showthread.php?t=54143 '92 JDM Alcyone SVX Version-L 4WS Ebony~ http://www.subaru-svx.net/forum/showthread.php?t=54117 Last edited by NeedForSpeed; 09-22-2004 at 11:14 PM. |
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Did you think about makeing the short pipes between chambers a larger diameter? say something like 3 inch?
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#3
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Good stuff! I had my machinist "pop open" a spare stock muffler I have a couple of weeks ago. We took pictures with his digital camera, but he's been too swamped with work since then to email them to me. We're actually planning on hooking a flow bench up to it to "play" a little. I've actually been considering opening up the end "ribs" and closing off the next "rib" in on each end to make larger end cavities. I've also thought about replacing the existing pipe with larger pipe, but I think you'd have to remove the entire "wrapper" from the muffler to be able to remove the existing pipes and weld in new ones.
-Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#4
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Quote:
-Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#5
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Cuttin metal and shootin sparks is FUN!
Nice job Ron!
Todd
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Down to none |
#6
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Quote:
What are you smokin' Chike? Todd
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Down to none |
#7
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Such madness isn't cheap,
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Bill, I only took one picture, that with a disposable camera. Please post your digital pictures here, everyone will be amazed at what they see. Subaru spent alot of money developing and producing this piece to be quiet and to last. What did you use to open it up? Did you open the top between the outside rows of spot welds like we did? Interesting comment on enlarging the outside cavities. Essentially, that is what we did by leaving the two inch section of pipe passing through the end chambers to the tips intact. The short end chambers can not exit exhaust. The far end can receive some exhaust pressure and redirect it through one of those tubes back toward the center of the muffler. Only the end farthest from the inlet has this redirection tube. The inlet pipe is cut at an angle, with the pulse directed to the near end. Wish we would have taken time for more pics, but we were hustling to get the rear diff gears swapped the same night. Mike, enlarging pipes would be difficult and probably not helpful. The entire muffler would have to be disassembled to enlarge the holes in the walls/ribs for larger pipes. When you see pictures, it will be obvious. Believe me, if all the pieces were new and disassembled, if would be nearly impossible to weld this thing together. The short pipes are probably for sound tuning or pressure balancing, not to direct exhaust out of the muffler. Two of these short pipes of different length are in the top row, on longer pipe on the very bottom, and two long pipes to the tips.
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Special Thanks to Our Friends and Sponsors: * http://www.alcyone.org.uk/ssm http://www.PhenixWheels.com http://www.dba.com.au/ http://www.ClassicSoftTrim.com http://ToyoTires.com/tire/pattern/versado-lx Gillman Subaru of Houston "QuickChange" http://www.TransGo.com/ http://www.PlanetSVX.com Bontrager Works, '92 Subaru SVX LS-L Claret ORIGINAL OWNER '92 LS-L Pearl~ '92 LS Pearl~ '92 LS-L Teal~ '92 LS-L Silver~ '95 LSi Polo~ '92 JDM Alcyone SVX Version-L 4WS Pearl~ http://www.subaru-svx.net/forum/showthread.php?t=54143 '92 JDM Alcyone SVX Version-L 4WS Ebony~ http://www.subaru-svx.net/forum/showthread.php?t=54117 |
#8
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Re: Cuttin metal and shootin sparks is FUN!
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Special Thanks to Our Friends and Sponsors: * http://www.alcyone.org.uk/ssm http://www.PhenixWheels.com http://www.dba.com.au/ http://www.ClassicSoftTrim.com http://ToyoTires.com/tire/pattern/versado-lx Gillman Subaru of Houston "QuickChange" http://www.TransGo.com/ http://www.PlanetSVX.com Bontrager Works, '92 Subaru SVX LS-L Claret ORIGINAL OWNER '92 LS-L Pearl~ '92 LS Pearl~ '92 LS-L Teal~ '92 LS-L Silver~ '95 LSi Polo~ '92 JDM Alcyone SVX Version-L 4WS Pearl~ http://www.subaru-svx.net/forum/showthread.php?t=54143 '92 JDM Alcyone SVX Version-L 4WS Ebony~ http://www.subaru-svx.net/forum/showthread.php?t=54117 |
#9
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Quote:
-Chike
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"Wise men talk because they have something to say; fools, because they have to say something." - Plato 2013 Cosmic Blue 5spd Evo X GSR 2006 Galaxy Gray 6MT RX-8 (sold) 2006 Steel Gray WRX TR (sold) 1996 Brilliant Red SVX L (sold) |
#10
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I'm definitely interested in seeing the pictures.
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
#11
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Re: Such madness isn't cheap,
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__________________
Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#12
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Bill,
Yes, those two unequal length pipes on top must be for balance or tuning because they aren't anywhere near the flow path or exit of the muffler. Did you notice the longer pipe in the bottom? We used pneumatic circular disks, maybe four or five. The double layer side, where the skin wrapped over, really ate those disks. I agree, it took a few minutes to figure out the flow path, if in fact there was one. My first impression was a pipe organ, lots of pipes, and walls to separate the muffler and locate those pipes. Though not designed for max power, this thing is a musical instrument! Your pictures will be interesting to all, as this is really one amazing Subaru piece, unique to the SVX. I'm further impressed about Subaru's attention in designing and producing the SVX. This muffler may have had a different song in non-US cars; fewer if any cats, lower gears, etc. After Subaru installed three cats for US cars, perhaps the unique song it was designed to sing was never heard. What a show piece, to have one of these 'popped-top' mufflers hanging the shop wall. It is a work of art for sure. While we were working on the muffler at our friends rod restoration shop, a friend of his stopped by. He was a high-school shop teacher. He found the piece very interesting, and expressed interest in hearing the 'hacked' piece.
__________________
Special Thanks to Our Friends and Sponsors: * http://www.alcyone.org.uk/ssm http://www.PhenixWheels.com http://www.dba.com.au/ http://www.ClassicSoftTrim.com http://ToyoTires.com/tire/pattern/versado-lx Gillman Subaru of Houston "QuickChange" http://www.TransGo.com/ http://www.PlanetSVX.com Bontrager Works, '92 Subaru SVX LS-L Claret ORIGINAL OWNER '92 LS-L Pearl~ '92 LS Pearl~ '92 LS-L Teal~ '92 LS-L Silver~ '95 LSi Polo~ '92 JDM Alcyone SVX Version-L 4WS Pearl~ http://www.subaru-svx.net/forum/showthread.php?t=54143 '92 JDM Alcyone SVX Version-L 4WS Ebony~ http://www.subaru-svx.net/forum/showthread.php?t=54117 |
#13
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I guess no one has opened up a Stebro muffler yet?
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David B. SVXipedia @ SVX-IW.COM -- SVX Information Warehouse 2.0 coming...eventually! Ebony 1992 SVX LS-L 5 spd Koni/GC Stebro 187k miles RIP (Rust In Pieces) 1993 SVX 5 spd Koni/GC Stebro Polyurethane bushings still available! |
#14
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The Stebro
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Special Thanks to Our Friends and Sponsors: * http://www.alcyone.org.uk/ssm http://www.PhenixWheels.com http://www.dba.com.au/ http://www.ClassicSoftTrim.com http://ToyoTires.com/tire/pattern/versado-lx Gillman Subaru of Houston "QuickChange" http://www.TransGo.com/ http://www.PlanetSVX.com Bontrager Works, '92 Subaru SVX LS-L Claret ORIGINAL OWNER '92 LS-L Pearl~ '92 LS Pearl~ '92 LS-L Teal~ '92 LS-L Silver~ '95 LSi Polo~ '92 JDM Alcyone SVX Version-L 4WS Pearl~ http://www.subaru-svx.net/forum/showthread.php?t=54143 '92 JDM Alcyone SVX Version-L 4WS Ebony~ http://www.subaru-svx.net/forum/showthread.php?t=54117 |
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Re: The Stebro
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Mychailo :: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ :: 1995 Laguna Blue SVX L AWD 5MT (sold) Visit my locker SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads. |
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