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Old 11-10-2009, 08:00 PM   #1
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Default Is a flex tube 100% necessary on the DP?

I searched and was surprised not to see anything on this.

I have a feeling the answer is yes. But i'm absolutely out of cash at this point and cannot afford to buy one right now.

Even if I can just get by without one for a few weeks while i'm job hunting/get a paycheck. I can weld one in later no problem.

I really just dont see how a downpipe could possibly last without one though...
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Old 11-10-2009, 08:02 PM   #2
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I don't have one on mine so far so good.
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Old 11-10-2009, 08:05 PM   #3
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I don't have one on mine so far so good.
******* awesome. That is exactly what I wanted to hear.
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Old 11-10-2009, 08:24 PM   #4
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my friend didn't put one on his. couldn't wait 1 day for our usual exhaust guy to work on it. so he got it done somewhere else and the next day he got on it and cracked his $1000, 3month wait, custom exhaust manifold.

so if you have to drive it like that, don't floor it!
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Old 11-10-2009, 08:31 PM   #5
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you absolutely HAVE to have a flex pipe somewhere... but you'll be ok for a little while without one. My exhaust broke one or twie a year withoput one, for around 3 years...
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Old 11-10-2009, 08:43 PM   #6
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yea i would recommend one, my friend didn't have one on his 240 and he broke an exhaust manifold a few times without one
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Old 11-10-2009, 08:44 PM   #7
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bleh...
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Old 11-10-2009, 08:46 PM   #8
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For what its worth I plan to get one on mine as well. I definitely don't think its good that I don't have one now. The local metal place wanted to charge me 60 for a tiny *** 4" flex section. I told them to stick it up their ***. Once I find a cheap one I'll weld it in.

I recommend you do the same.
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Old 11-10-2009, 08:48 PM   #9
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I don't have one. Greddy cast manifold, greddy turbo, the used kit came with a custom 2.5" DP, bolted to 2.5" mid pipe that's welded to a 2.5" cat, then VTA. I had more pipe after the cat going to a magnaflow muffler for about a year, and so far about 1.5 year without the muffler, a dozen or more track days, no cracking.
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Old 11-10-2009, 08:50 PM   #10
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I think its needed, especially the way the BP shakes, its not the smoothest engine in the world
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Old 11-10-2009, 09:27 PM   #11
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Quote:
Originally Posted by spoolin2bars View Post
my friend didn't put one on his. couldn't wait 1 day for our usual exhaust guy to work on it. so he got it done somewhere else and the next day he got on it and cracked his $1000, 3month wait, custom exhaust manifold.

so if you have to drive it like that, don't floor it!
Quote:
Originally Posted by airbrush1 View Post
you absolutely HAVE to have a flex pipe somewhere... but you'll be ok for a little while without one. My exhaust broke one or twie a year withoput one, for around 3 years...
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Originally Posted by WildMride View Post
yea i would recommend one, my friend didn't have one on his 240 and he broke an exhaust manifold a few times without one
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Originally Posted by Full_Tilt_Boogie View Post
I think its needed, especially the way the BP shakes, its not the smoothest engine in the world
no to all of these.

I've had zero flex pipe on my home built system for so many miles it's not even funny. I put my turbo on in 2004 or something?

Just dont use a hanger between the turbo and the stock hanger thats under about where your asscheeks are. DEFINITELY DO NOT bolt it to the transmission!

Mazda Comp engine mounts help too.
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Old 11-10-2009, 09:35 PM   #12
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Originally Posted by y8s View Post
no to all of these.

I've had zero flex pipe on my home built system for so many miles it's not even funny. I put my turbo on in 2004 or something?

Just dont use a hanger between the turbo and the stock hanger thats under about where your asscheeks are. DEFINITELY DO NOT bolt it to the transmission!

Mazda Comp engine mounts help too.
Please tell me why not.
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Old 11-10-2009, 09:40 PM   #13
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Quote:
Originally Posted by 18psi View Post
Please tell me why not.
Kinda curious about that myself. My DP is coupled to the bellhousing via a U-bolt and a bracket, with the flex section just aft. Or at least it was until the U-bolt fell off last week. Made a really horrible sound just before it hit the pavement. Still, no problems after 3 years. Just glad I didn't hole a tire on it.

But yeah, you need a flex section somewhere or else your manifold will break into three pieces and your dick will fall off.
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Old 11-10-2009, 09:52 PM   #14
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Im running my Absurdflow with no flex. Paul's Machine has no flex. No problems whatsoever.
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Old 11-10-2009, 10:00 PM   #15
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Quote:
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But yeah, you need a flex section somewhere or else your dick will fall off.
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Originally Posted by ArtieParty View Post
Im running my Absurdflow with no flex.
I rest my case.
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Old 11-10-2009, 10:10 PM   #16
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Ouch.

I am pretty sure none of the 'street' manifolds I have done have a flex section except for Evan's MSM; everyone else was too cheap None of them have cracked.

I now require them on the 'track' downpipes I do.

Make sure you fully weld on the inside of the downpipe flange and do at least strips on the outside of the flange, if not also all the way around.
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Old 11-10-2009, 10:11 PM   #17
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Careful Anton, I don't know if ^ knows what he's talking about.
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Old 11-10-2009, 10:13 PM   #18
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Quote:
Originally Posted by curly View Post
Careful Anton, I don't know if ^ knows what he's talking about.
Seriously dude I was just thinking that. This turbotim guy doesn't know his *** from a hole in the ground when it comes to fabrication.

Thanks guys, i'm going to fearlessly procede without a flex pipe and will make sure I have one in place before my first track day next season. This saves me some cash for sure that can go toward some bitchin hardware or something.
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Old 11-10-2009, 10:14 PM   #19
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Quote:
Originally Posted by Joe Perez View Post
Kinda curious about that myself. My DP is coupled to the bellhousing via a U-bolt and a bracket, with the flex section just aft. Or at least it was until the U-bolt fell off last week. Made a really horrible sound just before it hit the pavement. Still, no problems after 3 years. Just glad I didn't hole a tire on it.

But yeah, you need a flex section somewhere or else your manifold will break into three pieces and your dick will fall off.
I have a bad case of not reading the entire thread before posting. so...

My very first downpipe (racing mazda for the greddy kit) didn't last long when attached rigidly to the bell housing. Maybe a few weeks? That stuff needs to move around with heat, especially stainless DP's. If running no exhaust, a not so rigid bracket would be a good idea towards the end of the DP, I'd use one of those reinforced hard rubber exhaust hanger strap things and a U clamp.
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Old 11-10-2009, 10:16 PM   #20
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Careful not to seize your Motec muffler bearings though
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