Flex pipe

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This morning I installed a 12" section of stainless steel wound flex pipe with two band clamps in the exhaust between the turbo and cat. The results are good! A noticable reduction of noise in the cab as well as standing next to the truck with it idling. The exhaust note is there but the ringing of the exhaust is almost gone.


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Steve McDaniel
98 ClubCab 12v 5spd 4. 10
97 Stratus
92 Harley Fatboy

 

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Can you give a little more detail about this flex pipe you installed?

What was the problem that you were trying to fix? Were you going after a larger pipe?

Tim

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94' 2500 4x4, std cab, 12v, 5spd, gauges, TST 230/605, 110k mi.
96' 2500 4x4, ext cab, 12v, 5spd, Cummins Exhaust brake, 50k mi, (wifes).
Phx, AZ

 

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The section of flex pipe is to quiet a deep ringing drone that comes off of the outside of the exhaust pipe. Not the pleasant throaty exhaust note. If you've ever dropped a long piece of 3" pipe, you know just how loud it rings and the deep tone it produces. Imagine holding a 12' length of stainless steel pipe against the Cummins and the noise it would make form the vibrations. We have a 12' long 3" diameter tubular bell hanging under our trucks. The flex pipe helps to isolate the vibrations from resonating down the length of the exhaust and through the floorboard into the cab. Apperantly some are worse than others. My truck is still noisy but that ear pearcing drone is all but gone. Now it's more of a pleasant throaty rumble with some turbo whine and staccato diesel clatter! We can have a normal conversation and listen to the stereo without competing with the drone. I have some pics of the setup if you're interested. I need to break down and send in some pics but I'm not sure where to send them. I don't see a link on the reader's rigs page.

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Steve McDaniel
98 ClubCab 12v 5spd 4. 10
97 Stratus
92 Harley Fatboy

 

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Steve.
post those pictures if you can I would like to see them Thanks Tom

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97 Ram 2500 Driftwood 5spd 3:54 E-brake Isspro,boost&pyro guages

 

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Sounds like a real cheap alternative to hard pipe. DO you think there would be any problems with wiggle on the turbo or rest of exhaust. I was going to use flex tube to replace my muffler, but the local exhaust guys said it would be hell on the rest of the system. (moving around and such)
Jack

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97 Red, slide in camper, Trails West 2 horse slant trailer, K&N air, 255. 85. 16 Big O XT, Banks Stinger Plus(minus exhaust), 4" BD exhaust (minus the muffler), A pillar gauge mounts, after market overload springs

 

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You guys might want to try what I did. It is easier than cutting the pipes. I bought a 2"x50' roll of Thermo-Tec exhaust wrap. I wraped the exhaust from the turbo(exhaust side) down to to cat. I have the turbo & exhaust blanket from genos garage and wanted to complete the job right. They say by keeping the exhaust gases from cooling, the exhaust velocity can remain high, thus improving the scavanging effect. Hard to tell if it improves performance, but I`ll bet it would quiet the ringing noise. It acts like an insulator..... Just an Idea ;-)

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1994 Dodge Ram SLT Cummins 5 speed 4x4, XLerator airfilter,Optima red top batteries,Turbo&Exhaust blanket,Magnaguard rear diff cover,Edelbrock IAS shocks,muffler removed,Borgeson steering shaft,Trailmaster steering stabilizers,Rancho upper & lower links,Polyurethane sway bar bushings,Skyjacker 2" leveling springs(front),Fabritech Stage II Traction Bars,Denman Coyote A/P LT305/85R16(36" Tall) tires on Stock Dodge Chrome 16x6. 5 wheels,Bushwacker Street Flares,Back-off saftey brake light,Bugflector II bug shield, Royal Purple ,Amsoil& Red line lubes throughout.

1970 Plymouth Cuda (under construction)
1968 Hurst HEMI® Dart , Nah its just a screen name ;-)

 

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Horseman,
The stainless steel flex pipe I bought is pretty stiff. It's not the cheap stuff. I don't think there would be much more wiggle under there than is already there with the rubber exhaust hangers. The difference is with the flex pipe installed, the wiggle and vibrations are isolated from the turbo. The flex pipe isn't cheap though. If you're concerned about using the flex pipe in place of the muffler, it'd be about the same cost to order up a ME kit from Geno's garage.

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Steve McDaniel,
98 CC 4X2 12v 5spd 4. 10
97 Dodge Stratus
92 Harley Fatboy

 

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I have already used a straight piece of 4" pipe to replace the muffler. Meineke welded it for me for FREE!! (They charged $40 to install the 4" cat back with muffler) I wonder how one could go about putting 4" stainless steel flex pipe from the turbo down. I'm not sure how you could mount it to the turbo outlet.
Jack

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97 Red, slide in camper, Trails West 2 horse slant trailer, K&N air, 255. 85. 16 Big O XT, Banks Stinger Plus(minus exhaust), 4" BD exhaust (minus the muffler), A pillar gauge mounts, after market overload springs

 

[Archive]

Horseman,
That thought crossed my mind after reading on the Cummins mail list that a member ran stainless flex from the turbo to the muffler. He said it really quiets things down. Mine is quiet enough now with the 12" section but I might do it just for kicks. If I do, I'll cut the downpipe 4" from the turbo exhaust elbow and attach the flex with a new 3" band clamp.

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Steve McDaniel,
98 CC 4X2 12v 5spd 4. 10
97 Dodge Stratus
92 Harley Fatboy

 

[Archive]

Steve, I just picked my new rig up last night and have racked up 100 miles running around town already! I think my exhaust rings like yours did, kind of a melophous, resonating drone around 1500-2000 rpm when accelerating/decelerating. The fact the exhaust has a long straight section of pipe is the reason this sound is produced. Straight pipe has a resonant frequency (based on diameter & length) and when exhaust pulses/engine vibration happens to match it, the pipe becomes musical!. If the exhaust could be fabricated with a couple of slight S-curves in the long section it should reduce the ringing effect considerably. Pipe organs have long straight pipes for a reason!

OK so that's theory. To reality, Steve, how difficult was it cutting your pipe? Did you rent the cutter?

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Vaughn MacKenzie
Tri-Cities, Washington

1998 3/4T QC 4x4 Longbed, 24-valve 5-spd, White over Driftwood, Leather & Loaded, foglights, LSD, HD Xfer Case, DeeZee Running Boards.

 

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Howdy Vaughn,
I bought a tailpipe cutter from Autozone for about $20. 00. It looks kinda like a chain wrench with roller blades on it. I'm gald I bought it as it made easy work out of cutting the pipe while it was on the truck instead of fighting with pipes crunched by exhaust clamps.

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Steve McDaniel,
98 CC 4X2 12v 5spd 4. 10
97 Dodge Stratus
92 Harley Fatboy

 

[Archive]

Flex pipe part two. I crawled under my truck today to see how things are looking and to my dismay, there are two spots between the flex pipe and hard pipe that show signs of leaking. I'll have to loosen it off and apply some sealer in the joints. Might be a good idea to do this the first time to avoid a second go around.

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Steve McDaniel,
98 CC 4X2 12v 5spd 4. 10
97 Dodge Stratus
92 Harley Fatboy