Standard Port
The standard port is common to Australian RX-2s, 3s and 4s. In 12A form, it is good for around 130hp. With intake and exhaust mods they can produce up to 180hp with excellent driveability and fuel efficiency with outright air-flow being the limiting factor. These standard housings form the basis for mild, extend and bridge porting.
PRO'S: Standard drivability and fuel efficiency
CON'S: Limited scope for power
Mild Port
A mild port is the first step to rotary porting. This version has been "shaped" slightly with a metal porting tool towards the upper area of the port, increasing air-flow and top-end power without creating any significant drawbacks. The port design is suitable for the standard induction with around 200hp being achievable. A mild port is a popular choice for those wanting slightly improved performance without changing the standard engine’s characteristics.
PRO'S: Smooth driving, good for daily street use
CON'S: Slight fuel consumption increase
Extend Port
The extend port is a larger version of the mild port and works best with improved intake and exhaust systems. Typically with these modifications, the engine will start to exhibit the rotary’s signature rough idle, although the extend port’s is very slight. There is also a slight but noticeable loss of low-down torque below 4,000rpm. Importantly the increase in air-flow ability translates to the potential for around 220hp providing the best compromise for regularly-used street cars. This is the popular choice for those who don’t want the numerous drawbacks of a bridge-port.
PRO'S: Good power increase while retaining drivability.
CON'S: Increase of fuel consumption and noise and the need for modified intake and exhaust systems to maximise power.
