I have done both with the Racing Beat (one piece) headers and several times with home made individual flange headers. No problems either way. Also I made up an adaptor plate to use Periphery port headers

with the studs very close to the tubing and mate that spacing to the standard side port spacing with the wide stud spacing. So I ended up with two sets of sealing faces

 

In both cases the flanges supported the header pipes and the collector.

The muffler is supported in rigid mounts. Never a problem.

 

You can generate leaks with rigid cast iron flanges like the old reactor set ups, if you over torque the nuts. You crush the ends of the stainless gasket and then get a leak at the sides.

 

So, I stopped using the gaskets. There is little heat to deal with holding the flanges against the water cooled irons and rotor housings. So I tried

coating the flanges with way too much GE silicone bath tub caulk. It worked great but some flowed into the port and blobs of it were stuck out into the exhaust flow for weeks, and didn't even break of and go down stream. It is really tough stuff. Now I use a 1/4" bead of silicone one inch out from the port. No gasket at all. Never a leak.

 

You could try that then snatch the manifold off right after you torque it down to see how far the silicone migrated toward the port. Then adjust the bead size and location to keep the silicone just free of the port.

 

Cracked turbo manifolds are as common as mud. They are poorly designed and too thin in some places. I suspect the gaskets are no help in reducing stresses. You could mount the flanges with Belleville

washers in series, to provide an iron like clamping force but with slight movement caused by engine expansion.

 

I never used them but it is an option.

 

Lynn E. Hanover 

 

We're curious about 13B turbo exhaust flanges, is there any reason they need to be one flange for both pipes or do you think it will seal up fine with one per?

We're looking for small weight savings as well as easier to build up each pipe. The other ends of the pipes are floating with a double flange going into a collector.

 

Chrissi & Randi