Why do they crack?

[SKREMN]

Just got home from driving tonight nice night for it and then crack brumm brumm brummmm
there goes my headers again
I was driving pretty hard just under 9k shifts
and then this happend
I didnt hit anything and they didnt cool down quickly
It happend to port D a fortnight ago but i have had that repaird that was due to getting home after a hard drive and turning off the car with hot headders and cracked overngiht
since then I have had them ceramic coated

what causes these to keep going on my car?
its gettiong too hot?
they wernt glowing
they are custom made and are pipe inside flange so its the pipe is cracking with the welds
port C is totally off and port B is only slightly cracked A is fine

its an LS/Vtec


http://i19.photobucket.com/albums/b164/skremnLS/Head.jpg

http://i19.photobucket.com/albums/b164/skremnLS/Crack.jpg

[MRJDM]

hey there i seen the design if your header wen ur car was at gpc the bottom support is not strong engough to support your header as your header design is long try have a braket made half way up the header on the b adn c runner and bolt it to your block
regards mrjdm

[wynode]

You have a flex pipe yeah?

[SKREMN]

got a flexy

[SKREMN]

and my motor dosnt move around i got mount inserts and an extra mount so its pretty stiff

[T-onedc2]

How sure are you that the quality of workmanship is up to scratch? Possible sub-standard fabrication?:)

[EGB16A]

this happened to my stock b16 headers, but they were heat wrapped which is supposed to cause more stress on the welds causing them to eventually crack.

[**Ghost**]

damn i htought OEM headers were almost unbreakable, especially the 2 piece ones

how does heat wrap cause more stress on the welds?

1, its "tight" so less flex?
2. it somehow "traps' the heat onto the metal?

[SKREMN]

Just got back from the exhaust place
gonna get a bigger longer flexy mine is only small and tight
also mount the collector onto the block (like standard) this will stop the movment stress traveling up
now all the stress and flex of the exhaust travels onto the flange causing this to crack under the stress of the high heat
and its all warranty

[Zdster]

I was just about to ask how much all of that was going to cost and then I read the last line. Sounds like you have got a good exhaust place there.

[EGB16A]

damn i htought OEM headers were almost unbreakable, especially the 2 piece ones

how does heat wrap cause more stress on the welds?

1, its "tight" so less flex?
2. it somehow "traps' the heat onto the metal?

So did i, oh well they r replaced now!

I believe it is a combination of not having a flexie join, and with the heat wrap the heat is more or less transfered elswhere to dissapate, ie. either end of the exhaust system (more so out the back of course) but enough to have more heat build up at the weld. From memory it was the second or third pipe.

[b20b]

My grand ma can weld better than that blind folded . You get what you pay for . through those in the bin . Go and look at a real set and you will see a vast difference in the weld

[SKREMN]

well its not the weld thats cracked its the pipe?
so a better looking weld want help
I just want performance, not to look pretty

[superR]

what thickness is the pipe and what is it made from?

[SKREMN]

mild steel not shure how thick?

[kayot1k]

maybe its just cheap manifolds chu got there man.

[**Ghost**]

wot brand are these headers? not an expert but the bends look pretyt high quality

[j3z3z]

the bends look good. But man that is some shitty welding job. I dont have site training, but i am full accredited through tafe for all weld machines. If i wanted a weld job i can get one but i not into the buiness side of it, but damn that shit weld job right there! begginers crap

[j3z3z]

well its not the weld thats cracked its the pipe?
so a better looking weld want help
I just want performance, not to look pretty

The weld quality and where it is located is the problem. Shit weld and high temps dont last together

[DynoDave]

Headers normally crack on the flange because the support bracket is not stiff enough to stop the headers from moving under acceleration and deceleration, and because these where such a long set of headers this will make the problem worse than normal.Another problem is if all 4 pipes are welded into the collector and there was any stress in the pipes from the building stages that will also cause the cracks as it is a stress point.
Regards Dyno Dave

[SKREMN]

I have no support brackets
Thats what i'll be adding now

[b20b]

well its not the weld thats cracked its the pipe?
so a better looking weld want help
I just want performance, not to look pretty

The weld becomes part of the pipe that is the process of welding
Not understanding such things will only get you in more trouble
:!: :!: :!: When I stated it didn t look good . A good weld is a strong weld and a good weld will usually look good. Robotic welds are normally excellent Look at a apexi N1 muffler for a example ...Some exrteme cases a weld is x rayed to insure no cracks

You wont see a Formula one exhaust with a big blob of dagy weld on it they are built for performance:thumbsup: