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...heading for 500+ RWHP
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I am trying to find out if a flex section on a down pipe is a nessecery thing to have or if it is just recomended. Will not having a flex section stress the elbow flanges too much?
 

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white guy
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I have becauseicans downpipe, doesn't have a flex section, adds more stress for sure, I haven't noticed any problems tho....
 

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SP-61GT powered
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I kind of wish I had a flex section now. I have to tighten the bolts that hold my elbow to the turbo monthly or else it will leak.
 

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Republican
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I have always worried about the strength of the dp, without a flex section, kinda worried it might snap sometime....
 
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I was going to buy becauseican's DP soon. But im thinking a flex pipe is a good idea. I have read mixed feelings.

It seems that obviously the only reason it is there is for when the engine twists due to torque, but it doesnt move THAT much. I imagine the exhaust system should have that much shimmy in it.

I guess worst case, if it is a problem, you could get a 3" flex pipe and weld it in there.
 

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Not ur jizz, not ur bizz
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DONT BE A....TO THE NEWBIE!!!!!


say it nicely :D
 

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25psi = 14" brakes :)
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Do a search, but think about this while you conduct the search.
When your car bottems out on a speed bump, and your DP hits the bump, what happens to your CT's exhaust housing?????
CRACK goes the housing, and you can pull out your wallet and buy a new one.
This may not be such an issue on the stock "Baja" Supra setup, but with any lowering springs, you will appreciate the flex section at every bump and scrape.
 

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No One Ever Listens To Me
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5,467 Posts
between THIS:

werkkrew said:


It seems that obviously the only reason it is there is for when the engine twists due to torque, but it doesnt move THAT much. I imagine the exhaust system should have that much shimmy in it.

and THIS:

adjuster said:

When your car bottems out on a speed bump, and your DP hits the bump, what happens to your CT's exhaust housing?????
CRACK goes the housing, and you can pull out your wallet and buy a new one.
This may not be such an issue on the stock "Baja" Supra setup, but with any lowering springs, you will appreciate the flex section at every bump and scrape.
thats why i say flex sections are GOOD! :)
 

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Dissident
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1,087 Posts
The reason Toyota included the stock expansion joint was to account for thermal expansion. Those two cats are heavy and needed to be rigidly mounted to the trans, so the expansion had to be taken up between the turbo and the mount.

An aftermarket downpipe does not need either the flex section or the rigid mount, as it will mostly likely not have a cat. The flex section is not for vibration or for absorbing engine twist. That's what the rubber hangers are for.

Flex joints are very expensive. More than the materials for the rest of the downpipe. They won't help flow either.

I think the only reason I'd want one is to make assembly a little easier.

Moral of the story: don't second-guess Becauseican's fabrication skills.
 

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Registered
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:stupid:

I have becauseican's DP without a flex joint and you can move that sucker all around and up and down and the only stress will be on the rubber hangers. That is what they are there for. It will not crack the DP and it certainly won't crack the exhaust housing of the turbo.
 

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white guy
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<---- Riding on H&R's with the becauseican DP, tho I it doesn't even hang down at all below the rest of the body, I have scraped a few times, no problems...
 

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No One Ever Listens To Me
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its simple....higher hp applications will have higher torque engines which WILL damage a DP without a flew joint... ive seen it firsthand......

id say anything over 400hp and the flexjoint is the safest way to go....of course im sure someone will say oh i have 450hp and no flex joint and no problems....well thats nice but ive seen it twice....engine torques cracks dp spend more money.......end of story.....
 

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Dissident
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IdealSupra said:
its simple....higher hp applications will have higher torque engines which WILL damage a DP without a flew joint... ive seen it firsthand......

id say anything over 400hp and the flexjoint is the safest way to go....of course im sure someone will say oh i have 450hp and no flex joint and no problems....well thats nice but ive seen it twice....engine torques cracks dp spend more money.......end of story.....
Impossible. Damage from from engine torque would require an opposing force. Admittedly, there IS an opposing force: the rubber hangers. However, I have a hard time believe those hangers have enough chutzpuh to damage steel.

Now, if someone installed a dp -and mounted it to the drivertrain- without a flex section, it would fail due to thermal expansion as I mentioned before.

For the record:
This is not simple.
Higher power does not necessarily mean higher torque.
Higher torque will not necessarily (or directly) damage a dp.
400 HP is an arbitrary number which doesn't correlate to peak torque.
This is not the end of the story.
 

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Registered
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What rubber hanger? My d/p hangs straight off the turbo and connects to the cat. There is a bracket hanging off the transmission, but I'm not using it. Even my stock d/p was clamped solid to that mount without use of a rubber hanger.

 

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ƒ=1/2π(√k/m)
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There is a BIG steel plate that gets attatched under the heat shield of the upper part of the stock DP, you should use it again when you put a new one in/.... makes the thing more structured, but you'll need to make some metal belt, or wire to wrap around it.

BUT

The rubber hangers are there for a reason, and if you reuse them... you should be okay w/o a flex section.
 

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Blackzilla
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MK3Brent said:
There is a BIG steel plate that gets attatched under the heat shield of the upper part of the stock DP, you should use it again when you put a new one in/.... makes the thing more structured, but you'll need to make some metal belt, or wire to wrap around it.

BUT

The rubber hangers are there for a reason, and if you reuse them... you should be okay w/o a flex section.
really? I tossed that bracket that mount it to the tranny away when I installed the new DP. Maybe thats why I developed an exhaust leak.
 

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ƒ=1/2π(√k/m)
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It's a good piece of metal....

And I thought it was a good idea to reuse it.

Maybe your motor mounts are getting rocky, and the shifting and torque from the motor is causing the 2 sections to weaken..

The cat section, and the new DP.
 
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