[cewrx7r1]

Extending the closing edge of the port does not change port overlap. It gives more time for the combustion chamber to fill up which affects the higher revs. The torque curve will be simiar to stock but extended to higher rpms with less affect at the lower rpms.The Racing Beat Street secondary ports are like this. Think of a cam with later closing and higher valve lift.

Inceasing the opening edge of the port also increase overlap which decreases low rpm torque but increases higher rpm torque more than just extending the close. PineApple primary and secondary ports are like this. Think of a cam which sooner opening, later closing, and more valve lift. The RB primary port is also like this.

The RB street port and PineApple medium ports idle about the same and are similar to stock ports with a smooth idle.