With double row of trachea models more beautiful and style, more exciting. Double pipe models can usually show the large displacement, good dynamic performance, proved its superior status, improve the rate of return, pull the wind. In fact, the double trachea and single exhaust pipe in principle, just two rows of trachea than the same caliber of a single exhaust pipe, exhaust more smoothly. The exhaust resistance is reduced, and the power of the engine is increased in disguise. The structure of exhaust pipe can be varied, single entry, single out, single out, double out, single out, double in and out, and two separate exhaust systems. The form of the exhaust pipe is ultimately determined by the displacement of the engine. Single outlets and double exits are available on both four cylinder engines and V engines, and the last independent dual exhaust system is used on the V engines. Single entry should be well understood. The inline engine requires only one exhaust passage, while the V engine is somewhat like a straight cylinder in two, with an exhaust passage on each side. And the "single out", "double out", that is, everyone in the mouth of several exhaust pipe. The decomposition figure of the automotive exhaust system, the front end is the catalytic converter, now every car to some things, and then in the catalytic converter before, is the car engine exhaust manifold, exhaust gas from the cylinder, we must first pass the exhaust manifold. After the first noise is complete, the exhaust gas is added to the rear silencer to further silence and eventually exhaust the atmosphere. Exhaust system, there are three main roles: First: reduce exhaust pressure; second: reduce exhaust noise; third: reduce exhaust pollution. What's the difference between one side of the exhaust pipe and one side of the two? The exhaust system makes noise. There are two kinds of noise, frictional noise and dynamic noise. Dynamic noise is the energy that the exhaust air carries itself, causing the sound of its own vibration. Friction noise is the sound produced by the exhaust air when it passes through the width of the exhaust system, the friction between the air flow and the exhaust system, the vibration of the exhaust system itself, and so on. Exhaust pipe in the end or both sides, the impact on the car is noise. The bilateral exhaust pipe produces less noise than the single side exhaust pipe at high speed. But the single side double exhaust pipe, compared to the single exhaust pipe, also can reduce the noise at the low speed. Are the two exhaust pipes better than one exhaust pipe? In general, a four cylinder engine using a single exhaust system with dual exhaust system, low speed difference, high speed since the friction noise dominates, dual exhaust system tailpipe noise than single exhaust system with low 2~7 dB, visible, the engine needs higher speed (usually better performance) the exhaust system is more willing to choose double outlet, but the use of dual exhaust system will lead to increased costs, installation space is more limited. Is the exhaust pipe as big as possible? The original exhaust system is the best setting for balancing the daily driving, practicability, comfort, environmental protection and performance of the automobile manufacturer through careful calculation and test. The general daily driving engine is running at low speed, the civilian vehicle exhaust pipe diameter is not too thick and the exhaust pipe bending is more, in order to maintain a certain exhaust back pressure, to meet the dynamic performance under low speed daily. Large diameter exhaust pipe, because the exhaust too smooth, insufficient pressure loss under low speed torque caused by the initial weakness, fuel consumption becomes higher, especially congenital lack of torque of small cars, more is to pay attention to this problem.