Standard Exhaust Manifold Issues

So I have the week off and I decided to make a new exhaust manifold. When I removed the old manifold, I heard a weird noise coming from inside the thing.

It seems to be a one way valve/flap to stop flow from cylinder number 1 feeding back up into cylinder number 2.

Notice the hot spot, the dry rusty area, as opposed to the wet looking area around the turbo flange. Excuse the filthy hand, its hard to keep them clean working on old cars like mine (2006 build) lol.


[YOUTUBE]HKcU0SenSzQ[/YOUTUBE]

I have seen a few posts on the US sites that confirm the flapper valve in the stock manifold, maybe thats what gives us the infamous burble in our exhaust note.

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Originally Posted by MattMPS3

I have seen a few posts on the US sites that confirm the flapper valve in the stock manifold, maybe thats what gives us the infamous burble in our exhaust note.

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I'll find out by the weeked about the flapper being the cause of the burble. I'm making a new manifold.

ah would like to see how the new one goes and looks

Quote:

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Originally Posted by 2XS

I'll find out by the weeked about the flapper being the cause of the burble. I'm making a new manifold.

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Most accounts I have read on the US forums is that once the manifold is changed the cars exhaust note is affected, usually not to the satisfaction of the owner.
If I were to hazard a guess its the removal of the flapper, and the fact that most aftermarket manifolds utilise a 4>1 collector design.