Polishing and Porting
The port design and finish of any cylinder head port offers the most direct and dynamic method of adjusting an engine's performance. It is important to understand that not every design will suit any given application and we therefore offer a number of 'stages' of development to maximise the gains in different applications.
The basis of the stage II cylinder head is fairly straightforward. The heads are created from a stock pair of cylinder heads dependant upon the application. The Heads are ported very slightly to remove rough edges and casting marks from the ports and chambers. Although this does slightly increase port volume it's primary goal is to reduce the obstructions in the port that offer the passing air resistance. This therefore creates a reduction in turbulence and drag and will allow more air to flow through the port in any given time whilst maintaining good air speed. These cylinder heads are generally seen as a slight upgrade to standard or a good starting point for forced induction applications.
The stage III cylinder head moves forward in the porting process by opening the chambers and ports to a greater degree. The heads are created from a stock pair of cylinder heads dependant upon the application. The Heads are ported with increased air flow, air speed and lower turbulence for fuel injection applications. This substantially increases port volume with the goal of allowing more air to flow through the cylinder head and into the combustion chamber in a given amount of time. The science behind this is fairly complicated, but if we look at it in essence as 'more air + more fuel = more power', you get the picture! This stage of porting is considered to be for road use vehicles which require a fairly high level of power increase but maintain as much driveability as possible. This port size and shape is often considered to be the best design for use with turbocharged applications.
At stage IV, the cylinder head ports have been fully re-shaped and opened slightly larger than a standard inlet manifold gasket. The chambers have been completely polished and 'bowled' to promote the best air circulation within the combustion chamber. Fitted with specially made shortedned, bulleted guides, the air flow through the cylinder head is maximised for fast road use. athis design is considered to be optimum for normally aspirated engines with performance in mind. Although there is still a little material left in the ports and chambers, they have been shaped and polished to get as much air through as possible without compromising air speed and 'swirl'.