The main function of an intake manifold is to distribute clean air – as far as possible, without pressure loss – from the air filter into the combustion chamber. As well as the throttle body, further components such as an air mass meter, sensors, EGR ducts, fuel rail and injection valves are integrated into the unit.
The performance and torque of combustion engines have been significantly improved through the develOPMent of variable air intake manifolds which can switch between different runner lengths. A short runner optimises performance at higher speeds, whilst a long runner provides favourable torque in the lower and medium speed ranges.