Shaping a Port

Small– and big–block Chevys feature a variety of rectangle, oval, and even cathedral ports, but not all are equal when it comes to airflow. "In terms of cross–sectional area to flow, an oval port is the most efficient because it has no sharp edges," explains Judson. "Air travels in the path of least resistance, and eliminating sharp edges minimizes resistance. If there’s enough meat on the head, ports should be oval." Some rectangle ports can be reshaped into ovals by filling in the corners with epoxy. Extending this concept into the intake manifold, runners that taper from the plenum into the port makes incoming air less sensitive to the changes in the contours of the port. This effect is more pronounced with longer intake runners, where taper helps out even more. "Air likes consistency, not a lot of changes."