Before we talk about the intake manifold, let's think about how the air got into the engine. In the engine introduction we have mentioned the operation of the piston in the cylinder, when the engine is in the intake stroke, the piston movement down to create a vacuum in the cylinder (that is, less pressure), good with the outside air pressure difference, so that the air can enter the cylinder. For example, we should all have been shot, but also saw how the nurse inhaled the potion into the needle barrel bar!
The imaginary needle bucket is the engine, so when the piston in the needle bucket pulls out, the potion is inhaled into the needle bucket, and that's how the engine sucks the air into the cylinder.
Due to the low temperature of the inlet, the composites began to become a popular intake manifold material, the light of which is smooth inside, can effectively reduce resistance, increase the efficiency of the intake.