Carpenter Race Engines - Cylinder Head Porting

Cylinder Head Porting Defined

Porting is basically opening up, re-configuring and re-surfacing the ports of a cylinder head. Why port a cylinder head? The simple answer is to let the engine breath easier and more efficiently and therefore produce more power.

Cylinder head ports fall into two basic designs; the Straight Shot port and the High Approach port. In a Straight Shot port, the design allows for a line of sight from the inlet directly to the front opening of the intake valve. Sometimes this design gives a lower flow value but because it is straight, we attain higher velocity of fuel/air entering chamber. It also creates a turbulent spin or swirling in the combustion chamber, yielding a more efficient and more complete burn.

A High Approach port is where a turn is necessary in the port design. The term "high approach" comes from angle of the last section of the port relative to the valve - it is more in-line with the valve stem.

We take advantage of this to get a full volume flow path in the complete 360° circumference of the valve. Making a turn to an airflow is problematic but we caress the turn - making it as moderate and efficient as possible - to use it in our favor. The straight shot into the opening yields a fuller, more uniform flow around the entire valve curtain. The advantage is that the complete valve opening is used more completely.

Which approach we take is based on the original design of the head. For example, the 1986-1990 GSXR head uses a Straight Shot port while the 1991-1992 GSXR head tends toward a High Approach port. The Hayabusa head allows us to use parts of both for the ultimate hybrid design.

Our Cylinder Head Porting Methodology

We take a very serious and methodical approach to cylinder head porting. The first step is to use the traditional method of hand porting using grinding tools and our past experience and knowledge for shape and sizing. The port is them run through preliminary tests on a flow bench.

Once a design looks good, we copy it
to all four cylinders and then go to the dynamometer for the real test. While the flow bench gives a good indication of how a port will work, the truth in is the dyno as it more accurately simulates re-world conditions and loads the engine.

We sometimes make as many a 30 pulls on a dyno to work in a design. After a few pulls the engine is removed, the head disassembled and ports re-ground to wring out every bit of power we can get. It is a painstaking approach but we feel it is the absolute best way to do it.

The final design is digitized utilizing a Renishaw Probe on our 5-axis Haas CNC machine. This allows us to trace our absolute best design and reproduce it exactly for each cylinder. One of the benefits of CNC porting is that each cylinder is an exact duplicate. If one cylinder is down on power we know it is not the porting and that takes a variable out of the equation.

The result is maximum power, consistency and reliability at a affordable price. Why take chances? Carpenter Race Engines offers the absolute finest in 4 cylinder big bore porting.