Hey guys I was wondering where I could find a stainless 180 degree 3" bend or j bend. I found one on burns, but obviously that isn't too cheap .

I previously just used a 90 degree bend and cut it into pie cuts to get a tight radius bend and clear my fan shroud. I took it to a reputable welder and got it tigged. I ran it just straight open downpipe and after about two weeks it has cracked. Its not hitting anything and hasn't been bottomed out. The only thing i can think of is too many vibrations and too many welds without enough support although i know people who have ran like this before without problems. I guess this next go around i'm gonna use the 180 so i can get a tighter bend without doing pie cuts and finally hook it up to an exhaust with a flex pipe. Thanks guys.

 

actually upon further inspection i think i will need a donut pipe instead to do these bends. What do you guys think?

 

some pics would help

 

Here is a pic of my setup with the first downpipe we made.

You can see how we had to make a tight bend to clear the radiator fan shroud. If needed i can get a pic of the latest downpipe that just cracked. The last one where i used a 2.5" transition so the bolts would fit in easier on the flange had much less clearance. Probably about a quarter of an inch away from the shroud.

 

Where is it cracking?

down a couple of threads theres some links mentioned in here:
https://honda-tech.com/zerothread/2126397

check the sticky @ the top for material suppliers for more bends.

 

the heaT wrap could be the reason why it cracked.....

I'm suprised because with open downpipe there is no weight on the thing at all....you sure it didn't hit anything while you were driving?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">

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why not run a pushed fan and tilt the rad a bit? that's what i did on my dc2 with neukin manifold. . . .i am not sure about D series trannys, but on the B series the clutch slave cylinder was kind of in the way so i had to have a section cut downpipe made anyway. . . .but without the puller fan there it really clears up a ton of room.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by G2turbo_terror &raquo;</TD></TR><TR><TD CLASS="quote">Where is it cracking?

down a couple of threads theres some links mentioned in here:
https://honda-tech.com/zerothread/2126397

check the sticky @ the top for material suppliers for more bends.</TD></TR></TABLE>
Thanks man. This is what i ended up ordering last night

Its cracked the last two times in the bend with the pie cuts. Whats strange though is on the first downpipe it cracked once after the final bend which was fixed. There werent even any pie bends around there

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by m R g S r &raquo;</TD></TR><TR><TD CLASS="quote">why not run a pushed fan and tilt the rad a bit? that's what i did on my dc2 with neukin manifold. . . .i am not sure about D series trannys, but on the B series the clutch slave cylinder was kind of in the way so i had to have a section cut downpipe made anyway. . . .but without the puller fan there it really clears up a ton of room. </TD></TR></TABLE>
I was trying to avoid running a non oem fan. The oem fan has always worked well for me and i see so many cars run hotter than i'd like using the slim fans. Although i'm prepared to go with one if i need to.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by m R g S r &raquo;</TD></TR><TR><TD CLASS="quote">the heaT wrap could be the reason why it cracked.....

I'm suprised because with open downpipe there is no weight on the thing at all....you sure it didn't hit anything while you were driving?</TD></TR></TABLE>
whats funny is on the 2nd downpipe i didn't use heatwrap and it cracked in half the time . Also it doesn't appear that it hit anything. No dents in the pipe and no scrapes both times. I wish i had some batteries in my camera so i could take a pic of my last downpipe for you guys.

 

Did the weld crack or did the tubing crack?

 

it cracked at the weld and spread throughout

 

maybe the weld wasn't fully penetrated?

 

you could see where it was penetrated on the inside.

 

I know this off the subject, but have you noticed much of a difference between your hf manifold and the log manifold you are using now?

 

maybe it was welded with a bit too much heat and became brittle

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbo1.5 &raquo;</TD></TR><TR><TD CLASS="quote">I know this off the subject, but have you noticed much of a difference between your hf manifold and the log manifold you are using now?</TD></TR></TABLE>
i'm not sure really. I switched out a lot of stuff in my setup all at the same time.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tigre Tuning &raquo;</TD></TR><TR><TD CLASS="quote">maybe it was welded with a bit too much heat and became brittle</TD></TR></TABLE>
its possible, but everything else i've had welded by this guy had done well. He is a pretty damn good fabricator, owns his own fabrication shop, and has been in the business for quite some time.

Whats strange is that even the first downpipe i had migged by one of my friend's cracked and he has done many downpipes in the same fashion on his setups with no cracks at all. The only difference is he always had an exhaust connected so i think whats causing the stress is having no exhuast/hangers/flex pipe to dampen the vibrations on the end of the downpipe.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">i think whats causing the stress is having no exhuast/hangers/flex pipe to dampen the vibrations on the end of the downpipe. </TD></TR></TABLE>

*nail on the head*

that's what i was thinking pretty much the whole time i was reading the thread. If there's nothing holding the bottom of the downpipe still, the vibrations will get stronger as they travel the length of the piping, it's not really if it will crack, but when.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by efKART &raquo;</TD></TR><TR><TD CLASS="quote">WTF is a 180 degree bend? I think that would be a straight piece of pipe...</TD></TR></TABLE>

lmao......its a u bend