The working principle of
For a natural intake engine, the intake manifold is located behind the throttle, so when the engine throttle is open for an hour, the cylinder can not absorb enough air, which will cause a high vacuum of the manifold. When the engine throttle is open wide, the vacuum in the intake manifold is reduced. For this reason, a jet fuel engine is equipped with a manometer in the intake manifold that is fed to the ECU to determine the engine load and to give the right amount of fuel.
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For a natural intake engine, the intake manifold is located behind the throttle, so when the engine throttle is open for an hour, the cylinder can not absorb enough air, which will cause a high vacuum of the manifold. When the engine throttle is open wide, the vacuum in the intake manifold is reduced. Therefore, injection fuel engines are equipped with a pressure gauge on the intake manifold to determine the engine load and give the right amount of fuel injection.
Intake manifold design is also a great deal of knowledge, in order for each cylinder of the engine to burn in the same condition, each cylinder of the manifold length and bend to be as same as possible. Since the engine is programmed by four strokes, each cylinder of the engine takes in air in a pulsed manner, and as a rule of thumb, the long manifold is suitable for low RPM and the short manifold is suitable for high RPM. So some models will use variable length intake manifolds, or continuous variable length intake manifolds, so that the engine can play a better performance in all speed range.
