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

 

Use mild steel flanges.

 

The stainless steel expands alot and cracks the studs. Use a mild steel flange or cut the stainless flange in a few places.

 

You could also consider drilling out the holes in the manifold flange. That would let the flange expand without jamming against the studs.

Evan

 

We have never had one problem...... but before going any further could we see some pictures of the cracking, maybe on the car and off the car. if you dont wanna post them you can always e mail them to casey@burnsstainless.com

 

stainless expands too much, use mild for the flanges

 

Hej guys.

Thanks for trying to help me.

What is MILD steel? I don´t know the german translation.

It seems as if the studs are not cracked - they seem to be sheared (hope the right word). So I´ll try to drill them a little out and cut som reliefs in the manifolds.

Thanks

 

Mild steel is also called plain steel or carbon steel.

 

Holes must be bigger on stainless than on mild steel.

 

this is a good debate... (mild vs stainless)

You could also countersink the holes so the stainless cant expand as much..

 

Yeah, it is a very good debate.

We have put together some headers over here...lol and i have never seen this but if they are shearing off i would tend to think something is wrong.

 

So what would be enough clearance around the head studs on a manifold constructed with a stainless flange?