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...

I don't have one on mine so far so good.

Fucking awesome. That is exactly what I wanted to hear.

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!

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...

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

bleh...

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 ass 4" flex section. I told them to stick it up their ass. Once I find a cheap one I'll weld it in.

I recommend you do the same.

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.

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.

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.

Im running my Absurdflow with no flex. Paul's Machine has no flex. No problems whatsoever.

I rest my case. :D

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.

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 ass 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.

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.

Careful not to seize your Motec muffler bearings though

That's what I'd do. Use no flex, if it breaks you can fix it now that you have the tools. In a year you'll be making these for everyone here. ;)

They will be named "ABSURD MEGA HYPERFLOW"

I like it! But the stickers would cost too much :td:

The whole deal with not running a flex in my system relies on the length between supports. in my case, it's long--basically the head to the one behind the rear o2 sensor somewhere (I forget and am above the car currently). That's a pretty long lever arm and it doesn't make the rest of the system move much.

Attaching it to the tranny shortens that lever arm. Also if you just do the easy "tack on a hanger rod" method, it focuses a lot of stress at one point. result: a hole ripped in your pipe where the hanger was.

Lol, Wankerflow.

Haven't had a flex pipe for months now and I have a hanger attached to the trans tail. No issues so far.
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Damn. That's the way I have had my dp for basically ever. no cracks or breakage but I'll definitely be on the look out.

Did you even get a thousand miles on your setup before your motor broke? :fawk:

Not that it's any scientific proof, but FM does not use flex joints in their downpipes and who knows how many they've shipped and are used. From their website:

"The pipes are cut and bent on a massive CNC (computer numerical control) pipe bender for consistency and accuracy. Due to the accuracy of the process, we were able to remove a heavy, expensive flex joint that was also a potential failure point."

I predict a catfight . Lol

:cry:

Actually since I've always had daily drivers I only put about 1k miles on my miata since the day I BOUGHT IT. 95% of those miles are WOT pulls though:D

I sold my suby though, so as soon as the motor is back in, the miata will be getting daily useage.


My 6 speed showed up today. I want to make love to it.

My FM downpipe does not have a flex pipe.

I wouldnt feel safe running over a cat without a flex in the downpipe :brain:

Seriously, if you do happen to bottom out the exhaust, a lack of flex will most likely mean cracked dp/manifold. Why risk it for $25?

Ha!!!

Here's the aforementioned flexibility that Tim made for my car:

http://www.shoremotorsports.com/pics...ust/MSMDP6.JPG

Same here maybe thats the key to the greddy manifold not cracking, no flex pipe ftw

Interesting debate.

I seem to want to agree with both sides as with having a car that sits pretty low hitting the exhaust seems to be pretty common and I imagine having that shock being able to be absorbed by a flex tube placed at the right spot in the system seems like it would do the job of saving parts in the long run.

My current downpipe is my exhaust and isnt but the distance from the turbine outlet to in front of the drivers side tire. No flex for me until I get the full 3in out the back. Im just worried about hitting hard things in the road.

When I got my downpipe fabricated I didnt even consider one. Never ran one and never had a problem. You dont 100% need it.

You and your cheap sources. :vash: I use a $80 "turbo" flex with the smooth inside.

hard-mounting to the transmission is also not a good idea.

http://www.boostedmiata.com/gallery2...serialNumber=1

hard-mounting to the transmission is also not a good idea.

http://www.boostedmiata.com/gallery2...serialNumber=1

hard-mounting to the transmission is also not a good idea.

http://www.boostedmiata.com/gallery2...serialNumber=1

:)

lol. :brain:

Two of my exhaust hangars broke which inevitably lead to my manifold stud failures. Tack welding hangars is FTL.

What a dumb place to cut corners.

lol

Maybe it's not such a bad place to get cheap given none of them have cracked.

I'd also point out that FM's current DP's don't have flex sections like they used to. Do they have a reputation for breaking?

I'd like to point out FM uses a 100lb cast dp elbow.

"The pipes are cut and bent on a massive CNC (computer numerical control) pipe bender for consistency and accuracy. Due to the accuracy of the process, we were able to remove a heavy, expensive flex joint that was also a potential failure point."

Ironic isn't it. "We saved 3lbs on your downpipe by adding a 20lb elbow."

I have one.. the cast piece isn't light but I'd put money on there being less than 6-7lbs of difference.

What I asked wasn't whether it's heavier but whether the current FM downpipe tends to break. If your only answer is useless sarcasm why bother.

butt hurt much....^^

Sandy vagina fail.

lol

Guess I have to spell it out for you. It can't break because they use a heavy wall, cast iron piece. FM has no place in this conversation because no one else uses a cast elbow. Just because they don't use one, doesn't mean one is not needed.

Tim on the other hand makes a fabricated piece, so if he doesn't use a flex, maybe one isn't needed. Either way, I'll take my cheap insurance.

My fabricated Greddy replacement DP didn't have a flex, and never had a problem with it (neither did the original DP either). My BEGI does have a flex and I wish it didn't. The flex is significantly larger than the 2.5" pipe leaving very little clearance around it, so getting the DP in a place where the flex doesn't rub is difficult.

honda civic doesn't have a flex...

Shakes? More like you probably have bad motor mounts.

For the record, I haven't had a flex pipe on any of the 3 turbo setups I have used and had no issues with cracking. But I also never attached it at the transmission and had good motor mounts.

Common sense....

Every other car I've owned, civic included, had some form of flex joint from the factory between the manifold and exhaust. Most OEMs use a donut and spring bolts.

I think Full-Tilt meant vibrating, not shaking. Not sure stiffer mounts would help there.

duh youre right. and dammit when i swapped midpipes i forgot the donuts.

Why do you need clearance at that location? I have a begi downpipe as well with a flex pipe and has had 0 problems with clearance around the flex pipe.

NB:ne:NA ? BEGI fit is inconsistent as hell?

op sorry didnt see that, nvm then :)