E30 Zone

If you have a six branch do you need the x pipe? And what does it do?

Yes.

Balances the pressure in the exhaust.

Ben

Thanks

No you dont have to have it, there are several 6 branch manifolds that dont use them.

The cross pipe is to generate "scavenging" effect. Imagine each branch having a slugs of exhast gas in them. As all these slugs move down and out of the pipe they drag the gasses out of the other pipes because the is a low pressure area behind them. So insted of exhaust gasses making their way under their own pressure they are effectively being sucked out of the head by the moving gasses in the other pipes. This all happens at the X pipe, and at the collectors, usually 2 on an am M20.

The position of the X can determine at what RPM the effect is at its highest.

So you don't have to have one, but you may make more power if you do.

you dont need one at all you can be perfectly fine without one or with a y-merge to a single pipe

Would it be best to put it closest to the manni then . I see the btb ones are about 300mm away from the manni where it joins. I've seen a couple on ebay and thought of doing it .

I remember someone saying it goes at the hottest point in the downpipes and to find this put some paint on them?

I could be wrong!

btb is 550mm from the end of the primary pipes. i wouldn't put it any closer

Nice one. Thanks for the input