Twinport is a design theory based years ago in old Porsche and Volkswagon engines, although the principle has changed! It produces a torquey motor from very low displacment run through a suitable gear box, whilst offering good fuel savings.
The Twinport principle is based on the ECOTEC four-cycle spark ignition engines and uses innovative methods to minimize the so-called throttle losses. These occur because the power output is governed by varying the fresh air supply to the inlet ports. In the new engines this induction resistor is skillfully reduced. At partial load, the four-cylinder engine receives up to 25% of its cylinder charge from previously burnt exhaust gas delivered through an additional line.
A major advantage of Twinport technology results from the fact that the conventional three-way catalytic converter remains in tact. This sets it apart from stratified-charge direct gasoline injection, which works with lean mixtures and requires an additional catalytic converter for the oxides of nitrogen. In addition, retention of the inlet pipe fuel injection reduces technical complexity and, consequently, the cost to the customer. This favorable cost situation makes the Twinport principle particularly attractive for compact-class cars, as power output and efficient fuel consumption are fully maintained.
