Getting the swirl right

In general, it’s actually quite simple: If you want something to burn, you’ll need oxygen – otherwise the fire will extinguish itself in no time. The same applies to a combustion engine. The only difference is that a highly complex interplay of different, precisely harmonised components is required in order to optimally supply the engine with the air required for combustion. The intake system, which is responsible for this, consists of an air filter box with filter, a mass air flow sensor, a clean air line, a charge air line, a charge air cooler, a boost pressure sensor, a throttle valve and an intake manifold module, which is also sometimes referred to as an inlet manifold, intake bridge or intake plenum.

The intake manifold module ensures that the engine receives the precise amount of air required and that the air flow is swirled with the injected fuel in such a way that efficient, complete combustion takes place with the lowest possible emissions to maximise power output. Some intake manifold modules are also equipped with a cooling unit to regulate the temperature of the intake air, as cooler air is denser, which can improve engine performance.

The so-called swirl flaps play a decisive role in the process described above, especially in today’s diesel engines. Their task is to manipulate the turbulence – the swirl – of the air flow entering the combustion chambers in such a way that a homogeneous mixing of air and fuel is achieved, thereby improving combustion efficiency and reducing harmful emissions. At the same time, swirl flaps can help to optimise the combustion process during cold starts. This is because the generated swirl achieves better mixing of air and fuel, which can improve ignition capabilities.

Sound simple to you? And these are just two of the components in what is a highly complex system. Any impairment or failure of even just one component can have a massive impact on the performance of the vehicle. So should there ever be a problem in this area: AIC offers a wide range of items relating to the intake system. Take a look at the “Intake system” topic in the spare parts catalogue – a completely illustrative overview focusing on the functions of the intake manifold and swirl flaps.