Somebody edumacate me
Le Mans Master
Joined: Aug 2000
Posts: 5,529
Likes: 1,943
From: Austin Texas
A ported intake has had someone go in there with a circular file and carefully remove material.
Much of the removed material is casting roughness allowing more of th physical passageway to flow air at lower resitance,
Some of the removed material makes it easier for air to flow (typically around corners, valve stem and guide)
Some of the material is around the bowl area (where the back side of the valve sits on it seat) causing the air to flow easier at low valve lift.
The key word is flow.
Note also: the missing key word is not volume.
Modern work is on on CNC machines, making each port identical to its neighbor.
ETA: In addition to the above, there is additional circular filing to make sure each port face is identical to the port face of the attaching component. This means that air flowing in the manifold "sees" no edge (instep or outstep) as it transitions into the cylinder head.
Much of the removed material is casting roughness allowing more of th physical passageway to flow air at lower resitance,
Some of the removed material makes it easier for air to flow (typically around corners, valve stem and guide)
Some of the material is around the bowl area (where the back side of the valve sits on it seat) causing the air to flow easier at low valve lift.
The key word is flow.
Note also: the missing key word is not volume.
Modern work is on on CNC machines, making each port identical to its neighbor.
ETA: In addition to the above, there is additional circular filing to make sure each port face is identical to the port face of the attaching component. This means that air flowing in the manifold "sees" no edge (instep or outstep) as it transitions into the cylinder head.
Last edited by MitchAlsup; Nov 27, 2014 at 08:53 PM.
