Real tech discussion on design, fabrication, testing, development of custom or adapted parts for Pontiac Fieros. Not questions about the power a CAI will give.
Ok, so I'm a cheap fiero owner. I bought a flex section that was fairly cheap. Not the cheapest one, but it was cheap. It has an internal braid and the size was what i wanted (short) so i picked it up.
When it was made, the end pipes were inserted into the flex section, and welded on the outside. Both ends were done like this. Can I cut these pipes off and weld my new pipes on as a butt joint? Can that lip be ground down? Or, should I not worry about it?
The rest of my headers aren't 100% perfect, but i'm doing all the little things i can while its apart. I couldn't find welded tubular collectors so I had to get formed, and I made sure to use bullets in the merge collectors where the pipes come together, all smooth mandrel curves etc.
I know this lip isn't a big deal, but it irritates me knowing that its there. Fix it or leave it?
Last edited by Jinxmutt on Sun Nov 07, 2010 7:06 pm, edited 1 time in total.
I did this on my flex joint. Mine looked much the same as your's, and I had space constraints. So I cut it at the welds, then welded my own pipe to it. Worked out fine, though I haven't run it yet so I'm not positive that it won't hurt anything, but I don't see how it could.
Sorry for the crappy pics, cell phone..
88GT 3.4 DOHC Turbo
Gooch wrote:Way to go douche. You are like a one-man, fiero-destroying machine.
nothing wrong with butt welding exhaust pipe. especially since you don't have an option when using v-clamps. the rings have to be butt welded to the tubing.
I had no problem butt welding the pipes, i just wasn't sure of the manufacturing/weld process for the braid, etc. I didn't want to cut it and have it come apart.
I'll chop it up and go from there, if its fails, its only a $30 lesson
it basicly has a spiral currogated tube through the center (so it can get longer/short or bend)
then it has some stainless mesh wrapped over the outside with two tapered cones pressed on and welded to keep that mesh inplace. and has similar done ont he inside to smooth the airflow.
from the description if you remove the pipe from the ends you will lose what is holding the inner mesh inplace.
So I've read a lot about this happening, and worried about the fact that I never decided to take my flex apart. People are insisting that you cut the internal braid out of the flex section. Well sure enough, just like MANY other people have reported, my flex has also failed. If you search around the turbo car websites, you will see a lot of this type of stuff, unfortunately, I'm now one of them.
CUT this stuff out!!!
Its tough to tell from the picture, but all the 'forward' facing braid has also folded back onto itself and is now facing the path of the airflow. Yeap, not good. Turbo looks just fine though, thankfully.
It can be done with a cutoff wheel, but it's a pita as the dia of the wheel is normally too big to get into the id of the flex, not to mention there's little room for error. I did one with an older cutoff wheel that was about half the diameter of a new one, which allowed me access inside the flex. The one pictured was taken out using a screwdriver and prying out the overlapping strands until the eventually were all out. Once you get one "weave" of the strands out you just continue around until they are all out. Once both sides are done you're left with a heap of strands on the inside that will easily come out.
95 Mustang
Dart 363, Victor CNC heads, Turbo people custom SR
PT88
AEM EMS
blacksaleen, post a build thread for your car, I'd love to see it!
I totally forgot about this thread, but figure I'd give my side of the story. I recently pulled my motor out to swap it to a new car, and that involved taking the headers off. They looked fantastic still, no cracks or rusting. However, when I saw the flex, I about freaked. The inner weave had "loosened", and shrunk in diameter. It was, no exaggeration, half the diameter it was supposed to be. I'm not sure how this happened, and I didn't get pics. The inner weave itself looked like the inner half of a doughnut, rounded to the middle. Almost like the ends had been pushed together, and the weave buckled inward. Luckily the turbo looked good, and the flex showed no signs that pieces had fallen off.
I promptly cut it off, and removed the flex altogether. I also heat wrapped the headers, so in theory its a very poor system from a reliability standpoint. The entire weight of the turbo and exhaust is supported by the Y-pipe and headers, they are heat wrapped with no flex, and there are no reinforcements. It'd be easy to fix, I've just lost motivation, and so far it's still working great.
88GT 3.4 DOHC Turbo
Gooch wrote:Way to go douche. You are like a one-man, fiero-destroying machine.
fieroguru wrote:I only buy the ones with the exposed corrogated tube inside... They are still quite cheap.
Same here, I replace alot of those and they all look the same inside, I don't want to put any on thats gonna dump more wire strands into the convertor.
That's good to hear. I'm getting tired of welding Jason's sprint headers back together. Hopefully I can get some longevity out of the set I build for the 3800 like you have.
You can buy these flex sections WITHOUT the internal braid. That's all I use. BUT, if you are going to mount this flex close to the header on a turbo or supercharged application, you might want to think about installing a pipe on the inside of the flex section and weld that pipe to the end of the flex the exhaust is coming into it from. This internal pipe's OD will need to be a little smaller than the inside diameter of the corrigated flex section so it won't rub on it, therefore you may need to use a bigger ID flex than you actually need.
Why the need for the internal pipe? The corrigated section of these flex pipes is made of very thin stainless steel and it WILL crack under the extreme heat a super or turbocharged engine produces in the exhaust. You need to protect these corrigated parts of the flex from the extreme heat of the exhaust flow, and an internal pipe will do the job.
