Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve quantity of the air flow. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to design and are made for maximum durability hence the thickness of the walls. A head can be engineered for maximum power, or for minimum fuel usage and everything in between. Porting the head provides the opportunity to re-engineer the airflow in the head to new requirements. Engine airflow is one of the factors responsible for the character of any engine. This process can be applied to any engine to optimize its power output and delivery. It can turn a production engine into a racing engine, enhance its power output for daily use or to alter its power output characteristics to suit a particular application.
Dealing with air.
Daily human experience with air gives the impression that air is light and nearly non-existent as we move slowly through it. However, an engine running at high speed experiences a totally different substance. In that context, air can be thought of as thick, sticky, elastic, gooey and heavy head porting helps to alleviate this.