Exhaust headers

[LanciaFin]

Hello,

I have had these new headers for three years, but just noticed, that in both the connection between front and rear cylinder banks seem quite a bit restricted (please see the attached picture.)

Was it someone's last working day at Imasaf factory, or was this signor Fessia's way to fight the unsafe effects of horsepower? Or is there some actual reason, why it has been designed like that (I have no previous experience about boxer engines?)

Unless stated otherwise, I'm going to grind the connection wider before installing.

Regards,

-Miika

[grifo63]

Uhmm, it looks like someone in IMASAF was drunk when made it:)-D

More seriusly I haven't any dismounted header to check at the moment but I don't remember any bottleneck and to me it doesn't make sense.

[FL30]

The port has to as far opened as possible. Had the same thing on aftermarket parts.

Hubert

[Geoff]

There can be some improvements by having some back pressure in exhaust systems, especially for torque, but this kind of restriction doesn't seem to make sense. So how about a "before and after" comparison?

[LanciaFin]

Well, usually the back pressure is designed evenly for all cylinders. I'll cut the openings properly before install. Mailed to Imasaf, but so far no comment from them.

[gcarenini]

Hello Miika,

I've read only now your post. I confirm that your manifold was wrongly made and you are right to cut the opening before install it.

With my kindest regards

Giovanni