Weber 45dcoe Manifold Port Shapes

[monty69 6]

Just removed twin 45s and intake manifold from s16 engine and noticed the manifold ports are round, where as the head ports are round with an extra small circle above this. Is this a problem in terms of airflow speed, swirl,volume? Surely the extra circle is there for a reason. Are all weber manifolds like this or is mine a cheap an nasty? I dont know the make of it but it says usa on it. I will be checking the ports actually match up when it stops raining!

[welshpug 1,627]

the small circle you mention is for the original injectors.

[Guest DanielVTS]

Just removed twin 45s and intake manifold from s16 engine and noticed the manifold ports are round, where as the head ports are round with an extra small circle above this. Is this a problem in terms of airflow speed, swirl,volume? Surely the extra circle is there for a reason. Are all weber manifolds like this or is mine a cheap an nasty? I dont know the make of it but it says usa on it. I will be checking the ports actually match up when it stops raining!

 

The extra bits in the head are to clear the injector spray pattern... not an issue with the carbs but if you want to optimise flow you should match them either by opening the manifold to match the head or by getting the head filled but this needs to be done properly to avoid getting lumps ot crap in your engine!

[benlilly 0]

As the miss-match due to the injector cut-out is downstream it shouldn't make much difference to flow, if any at all.

There might be improvements to be made elsewhere, but a flow bench might be needed to find them.