News - How to replace a car exhaust system?

How to replace a car exhaust system?

Common sense of exhaust manifold modification

The exhaust system modification is an entry-level modification for vehicle performance modification. The performance controllers need to modify their cars. Almost all of them want to change the exhaust system at the first time. Then I will share some common sense about exhaust manifold modification.

1. Exhaust manifold definition and principle

The exhaust manifold, which is composed of exhaust port mounting base, manifold pipe, manifold joint and joint mounting base, is connected to the engine cylinder block, centralizes the exhaust of each cylinder and leads it to the exhaust manifold. Its appearance is characterized by divergent pipes. When the exhaust is too concentrated, the cylinders will interfere with each other. That is, when a cylinder exhausts, it just encounters the exhaust gas that is not completely discharged from other cylinders. This will increase the exhaust resistance, thus reducing the output power of the engine. The solution is to separate the exhaust of each cylinder as much as possible, one branch for each cylinder, or one branch for two cylinders!

2.Why modify the exhaust manifold?

As we all know, the working process of the four stroke engine is “pressure absorption and explosion exhaust”. After the working cycle, the exhaust gas from the combustion chamber will be discharged into the exhaust manifold. Because the working order of each cylinder is different, the order of entering the exhaust manifold will be different. Considering the space and cost of the engine room, the inner wall of the manifold will be rough and the pipe length will be different. The problem is that the exhaust gas from each cylinder will eventually converge to the middle exhaust pipe through different distances. In this process, it is very likely that there will be gas conflict and blockage, and the gas resonance will also increase. The higher the engine speed, the more obvious this phenomenon will be.


The way to solve this problem is to replace the exhaust manifold of equal length, so that the exhaust gas from the cylinder can maintain a certain order and consistent pressure in the pipe, thus reducing gas blockage and giving play to the performance of the engine. The replacement of equal length exhaust manifolds to improve engine power is sometimes more effective than the modification of middle and rear exhaust.

Take a four cylinder engine as an example. At present, the most used exhaust system is the four out two out one (two exhaust manifolds converge into one, four out into two out, two pipes converge into one main exhaust pipe, and two out into one out) exhaust system. This modification method can effectively improve the performance of the engine at medium and high speed, and greatly increase the smoothness of exhaust.


3. The material of exhaust system affects the power performance and exhaust sound wave.

Generally, the exhaust system is made of stainless steel. The smooth inner wall can reduce the resistance of waste gas flow, and the weight is one third lighter than that of the original factory; The higher level exhaust system will use titanium alloy material, which has high strength, strong heat resistance and is about half lighter than the original factory. The exhaust pipe made of titanium alloy has a thin wall, and the exhaust gas will make a sharper and chopping sound when passing through; The sound made of stainless steel is relatively thick.

Now there is also an exhaust system that changes the exhaust sound through the electronic system on the market. This way will not affect the power performance, but simply changes the sound to meet the change of exhaust sound wave. 

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A well-designed exhaust system can indeed improve the power performance of the car, but it is necessary to find a suitable modification method! The modification should be careful, purposeful and prepared. The successful modification is based on your own needs. Do not follow blindly!

Post time: Dec-01-2022