A particular technical aspect of the SEAT 1.4l TSI engine is its active cylinder management (ACT). Volkswagen group is the first carmaker to implement this fuel saving cylinder deactivation technology on four-cylinder engines, as it was previously the preserve of large eight or 12 cylinder engines. Shutting down the second and third cylinders during low and medium load states reduces fuel consumption in the EU driving cycle.
Active cylinder Technology (ACT) mode of operation
ACT is active over an engine speed range between 1,400 and 4,000 rpm and torque outputs between 25 and approx. 100 Nm – a range that covers nearly 70 per cent of all driving states in the EU driving cycle. If the driver presses the accelerator pedal hard, both cylinders begin to work again without a noticeable transition.
All mechanical switchover processes take place within one-half of a camshaft rotation; depending on engine speed this takes between 13 and 36 milliseconds. What’s more, thanks to an accelerator pedal sensor and intelligent monitoring software, the system can also detect irregular driving profiles – such as during a drive through a roundabout or in sporty shifting on a highway. In such cases, cylinder shut-off is deactivated. The driver is aware of whether two or four cylinders are active by a related indicator in the multifunction display between the speedometer and tachometer.
ACT components
Altogether, the components of active cylinder management weigh three kilograms. Their actuators, the camshafts and their bearing frames are integrated in the cylinder head; two low-friction bearings reduce friction of the shafts. It is only with the TSI concept – petrol direct injection plus turbocharging – that a cylinder deactivation is even conceivable in its form today.
