Cylinder Head Porting; Turning Air Into Power
Updated: Nov 24, 2020
By: Greg Jones, Engine Builder Magazine
November 13, 2020
In general, the most critical areas when porting a cylinder head are those which pass the most air at the highest speed and for the longest duration.
Cylinder head porting is a fairly simple premise – increase airflow into the combustion chamber to make more power. However, making it actually happen requires a bit of work. Improvements to airflow quality and quantity come from porting in the bowl area between the valve seat and valve guide because it is an area of restriction.
Since every cylinder head is different, learning how to improve airflow characteristics involves a lot of trial and error and many hours on the flow bench to determine if port shape changes have made a difference. The actual act of porting or reshaping the ports generally involves a steady hand and a die grinder with an assortment of cutting, grinding and sanding tools attached. A skilled cylinder head specialist will focus on shaping the port to get the maximum flow with the minimal amount of enlargement so that maximum intake and exhaust air speed is maintained. Specialists are also trying to achieve equal flow through each port so each cylinder experiences a similar air speed.