Choice of materials for exhaust manifold.
12-25-2005, 05:42 PM
#11
1.5 BAR
Join Date: Feb 2005
Posts: 691
Re: Choice of materials for exhaust manifold.
Originally Posted by slappynuts
So are you trying to say that this makes a difference in a log manifold?Not that it matters because I use sch40 material with is much thicker.
It does not take special gasses to weld stainless,but it does take proper technique to weld with is time consuming and costs money(unless you want brittle welds with big carbon chunks inside your manifold ready to break off and destroy your turbo).
Its the extra expansion and contraction that causes manifold failure.When the log expands and contracts it causes nuts to start to loosen up and causes a host of other problems related to expansion.
The log can go through 8234237 heat cycles and nothing will happen to it as long as all of the welds penetrated all the way. Explain to me what would cause the log to fail if all the welds have fully penetrated. Do you think that mild steel doesnt expand? Mild steel expands a shitload too, just not as much as stainless steel.
12-25-2005, 05:48 PM
#12
1.0 BAR
Thread Starter
Join Date: Oct 2005
Posts: 216
Re: Choice of materials for exhaust manifold.
The log is expanding at a different rate than the head which leads to movement at the head be it either lov vs flange or log vs head.If you dont cut between the runners the manifold will turn into a bananna,if you do it will constantly loosen the bolts at the head.There is no way around this.
12-25-2005, 06:07 PM
#15
0.5 BAR
Join Date: Nov 2005
Posts: 106
Re: Choice of materials for exhaust manifold.
Don't the outer ends of the manifold compress harder against the head when the manifold is heated up? I think I recall this is why the old V8's exhaust manifolds get lesser torque settings on the hardware in these areas than the hardware in the center of the manifold.
Is this the "bannana effect" is wich you're referring to?
Is this the "bannana effect" is wich you're referring to?
12-25-2005, 06:59 PM
#17
3.0 BAR
Join Date: Dec 2002
Posts: 12,568
Re: Choice of materials for exhaust manifold.
im not questioning what you "know" i am just telling you my real world experiences.
people have been running manifolds for a long time, and ive never heard of or seen a problem. i know guys with flux core miggedlogs that have been going hard for years.
stainless all the way for me.
the price difference doest warrent the use of mild steel ever.
i have used quite a few stainless head flanges as well, also with no problem.
people have been running manifolds for a long time, and ive never heard of or seen a problem. i know guys with flux core miggedlogs that have been going hard for years.
stainless all the way for me.
the price difference doest warrent the use of mild steel ever.
i have used quite a few stainless head flanges as well, also with no problem.
12-25-2005, 07:02 PM
#18
0.0 BAR
Join Date: Mar 2004
Posts: 0
Re: Choice of materials for exhaust manifold.
All of what Slappy says makes sense. The fact of the matter is I have seen and built quite a few manifolds and some have been in heavy use for years with no problems. I guess if you intend on running really lean and high exhaust temp for 10 years then you may have an issue. Honestly how long do most guys run a manifold for?
12-25-2005, 07:37 PM
#20
1.0 BAR
Thread Starter
Join Date: Oct 2005
Posts: 216
Re: Choice of materials for exhaust manifold.
Originally Posted by tuname420
2 weeks
j/k.Alot of the 1.9t VW guys(elitist ****** :P) have alot of problems because they run high boost and extremely high EGTs.
