Intake System in Automotive Engineering

What is the function of the intake manifold in an engine?

Where can fuel injectors be mounted in the intake system?

What is the purpose of active intake manifolds in some engines?

Why must the inside diameter of the runners in the intake manifold be large enough?

What happens to the diameter of runners in active intake manifolds at high engine speeds?

Fuel injectors can be mounted:  by the intake valves of each cylinder (multipoint port injection),  at the inlet of the manifold (throttle body injection),  or in the cylinder head (CI engines and modern two-stroke cycle and some four-stroke cycle SI automobile engines) Intake System Intake Manifold The intake manifold is a system designed to deliver ______ to the engine through pipes to each cylinder, called runners.  The inside diameter of the runners must be large enough to avoid:  High flow resistance  low volumetric efficiency.  On the other hand, the diameter must be small enough to assure high ______ velocity and turbulence, which enhances its capability of carrying fuel droplets and increases evaporation and ______-fuel mixing Intake System Intake Manifold  Some engines have active intake manifolds with the capability of changing runner length and diameter for different engine speeds.  At low speeds, the ______ is directed through longer, smaller diameter runners to keep the velocity high and to assure proper mixing of ______ and fuel.  At high engine speeds, shorter, larger diameter runners are used, which minimizes flow resistance but still enhances proper mixing. The amount of ______ and fuel in on