Hello.
We got massive problems with cracking studs or bolds on cars with welded stainless steel turbo manifols on the head-to-manifold flanges and also on the manifold-to-turbo flanges.
The flanges are made of 10mm thick 304l and sometimes made of 321.
Meanwhile I chose one of the strongest (14.4strength here in Germany) studs that are available but the problem still exist.
The studs crack every few days and this weekend we had 4 broken studs at one day on two of our cars on a 1/4mile event.

I think it is caused by the bigger expandation of the 304/321materials against the cast materials, but there must be a solution ??!!

Every idea is very welcome!

PS: we never had these problems with cast manifolds.

Thanks in advance
Kevin

 

Are you cutting reliefs in the manifold to head flange? You've go to otherwise you'll keep cracking exh. studs like crazy. I dont know how to post pictures but I can try to explain where to cut em @. Inbetween each exh. port you should have one that goes from top to bottom (ground to sky) so that it can expand if it needs to. Sorta like this 0 l 0 l 0 l 0 the 0s being the exh ports and the l's being where you put the reliefs in. As for the manifold to turbo flanges, Im not sure what to tell you. It sounds to me like they need some expansion reliefs as well, but Ive never seen any on the manifold to turbo flanges before... Can you post pictures of the setup?

hth

Blaze

 

The problems are on several of our cars. Some ramhornstyle manifolds,some logstyle manifolds.
I know what you mean and also thought about this. But FullRace and the other brands also don´t use such reliefs.

In my point of view the expandation makes the flanges becomming thicker. So the materials strechtes the studs so much that they cracks.

What could be if I would use studs that are made of the same material like the flanges? Same expandation - problem solved????

 

actually the newest full race manifold I seen for a Sr20det motor did have the relief cuts

 

Ok. The newer styles may have these reliefs but as far as I know the older one don´t have.
Doesn´t the reliefs just prevent a side to side movement of the expanding material?

Do other people have the same problems? If yes, how did you fix it?

Kevin

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondaapi &raquo;</TD></TR><TR><TD CLASS="quote">Doesn´t the reliefs just prevent a side to side movement of the expanding material?</TD></TR></TABLE>

Ya, that's the thing, you might actually be *shearing* the studs, not cracking them. If the manifold expands along the head flange it'll act like a boltcutter on the studs. I was too lazy to cut relief flanges in my manifold, but I did overdrill all the off-center bolt holes to allow for some expansion without shearing the studs.

 

Hej!

This can be a things that I forgott.
If I remember back, I overdrilled one of my flanges. This manifold never had this ******* problem. I´ll try it out in the next days. If the problem still exist I´ll let you guys know.

Thanks so far

 

Use mild Steel flanges.
Most Stainless tubulr manifolds on the market have relief cuts