Turbo manifold design.

[Jörgen Karlsson]

The stock manifold has separate flanges, but since the manifold is pretty
strong it does not flex anyway.

My thinking was that if I used one large flange it would not get as hot as
the manifold itself. Maybe it would be 250ºC, thats a big improvement over
the 700+ºC temperature of the tubing.

Unfortunally the flange will only be in contact with the head at the ports,
if the head was flat like that of a Honda VTEC engine the flange would have
the same temperature as the head and all the stress would be on the tubes
and welds of the manifold itself.

I think that one problem are that when the manifold slides against the head
the nut does not slide against the manifold, the stud gets bent back and
forth everytime the temperature changes. But sometimes when the temperature
gets real high the nut might slides and gets stuck in an other position,
then when the manifold cools down the stud is breaks. I am pretty sure that
this is what happens.

One guy I know are sure that the studs break because of the weight of the
turbo, I don't belive in this since the studs break in the oposite end of
the manifold compared to the turbo. But the end where the studs break has
higher exhaust temperature then the end where the turbo is installed, that
supports my thermal expansion theory.

If I still get problems with this manifold I will have to install slip joint
at the outer runners, these leak a bit and I hope to avoid them.

Jörgen

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