The shape, length cross-sectional area of the intake pipe are different those of the intake hose, which represents the design charm of the engine. In terms of shape, the intake pipe can be divided into vertical inlet rotary inlet.

  The low intake resistance of the vertical intake helps to produce resonance improve intake efficiency at high rpm. At the same time, it is convenient to arrange the fuel nozzle. It is usually suitable for engines that emphasize high cornering performance; swirl will be generated in the air, thus improving the mixing degree of air gasoline, which is conducive to improving the combustion efficiency of the cylinder at low speed. It is usually suitable for engines that emphasize low speed performance.

  For example, BMW's trademark, the V10 engine installed on the M5, does use many complex technologies (such as Mitsubishi Honda in Japan) to improve the response speed of the engine, high power output at high speed, etc., but uses the most direct pure way to achieve the interpretation of high performance. Ten intake pipes of the V10 engine are of very short vertical design, each intake pipe is equipped with throttle valve. These are the most obvious design features that emphasize high speed responsiveness.

 The most obvious rotation of the intake port is the diesel engine. Generally, the speed of diesel engine is high. The focus is on the power performance at low speed. Therefore, the swirl inlet is used in diesel engine without exception. Some diesel vehicles also deliberately increase the rotation of the end of the intake port to produce large intake swirl improve the air fuel mixing.

 As the rotation speed increases, the speed frequency of the intake air become faster faster. The vortex generated by the inertia of the air flow has become the main cause of reducing the intake efficiency, which is conducive to the oil-gas mixture becoming more attractive to the cylinder. In fact, it's easy to understand. The air resistance of swirl pipe must be much greater than that of straight pipe. Therefore, at this time, the vertical air intake is more suitable for the working conditions of the engine.

Requirements of intake pipe shape for fuel injection nozzle

The two types of intake nozzles have different positions of fuel nozzles. The vertical intake pipe has simple shape, small floor area high intake efficiency. It is more suitable for in cylinder direct injection technology (such as Mitsubishi's GDI). Even like the BMW M5 V10 engine, the in cylinder direct injection can be used. The fittings are arranged very close to the intake valve.

In this way, the engine power responsiveness can be improved. However, the swirl inlet must use a more complex spiral shape, which will take up more space, so the general fuel nozzle is far away the inlet valve, the oil-gas mixture must go through a long distance to reach the cylinder, which greatly reduces the engine's response ability, part of the mixed gas will adhere to the inner wall of the inlet, the economy will be affected.