Exhaust and fuel consumption
Many drivers cannot imagine why an exhaust can affect the consumption of a car. Anyone who gets a little familiar with the technology will quickly see the connection.
Relationship between performance and exhaust
Look at the processes that make fuel move.
- An engine has an intake valve on each cylinder. When this is opened, a precisely dosed fuel-air mixture enters the engine's combustion chamber. It does not matter whether it is a two-stroke or four-stroke.
- The valve closes and the mixture is ignited. An exhaust valve opens and the burnt gases are directed into the exhaust. A piston moves at the same time. The speed and the force with which it is moved is decisive for the driving force of the motor.
- During these processes, it is important that the burned gases escape completely before new mixture penetrates the combustion chamber. The outlet is therefore of great importance for these processes.
- Without the exhaust system, the forces of the explosion would lead to strong vibrations that would hinder the movement of the piston in the cylinder. The damping of the shock wave is also important for the performance of the engine. In doing so, opposing forces occur. A back pressure is created in the exhaust which the exhaust gases from the engine have to overcome. In two-stroke engines, this exhaust back pressure is necessary to increase the compression in the engine. Without the exhaust, the mixture would be less compressed and the explosion would be weaker.
- At the same time, a flow is created in the exhaust gases, which empties the combustion chamber through the suction. This flow is also important in four-stroke engines.
Many mopeds and mopeds are equipped with a 2-stroke engine. Cars, on the other hand, will ...
In short, the performance of an internal combustion engine can exceed the Exhaust to be changed. Tuning companies use this fact, for example, when a sports exhaust is installed instead of a normal exhaust.
Possible causes for increased consumption
The shape, length and also the internal structure of an exhaust depend on the respective engine optimized. The engineers also take the counterpressure into account, because the fuel has to overcome it.
- If you have a leaky exhaust system, the back pressure is lower. The mixture can flow unhindered into the engine. This means that more fuel enters the engine than is necessary. Consumption increases. It is even possible for unburned fuel to spill into the exhaust.
- The vibration of the gas column in the exhaust is disturbed, the resulting suction is reduced and the combustion chamber no longer empties properly. The performance drops. Consumption increases because you apply more gas to compensate for this.
- In modern cars, sensors measure the flows and the back pressure in the exhaust. Depending on the results of the measurement, various control signals are triggered, which in turn determine the amount of fuel. If the exhaust has a hole, these values change. The control regulates the injection via the engine management in order to achieve the preset values again. This means that the engine no longer runs in the optimal range.
The better an engine is optimized using electronics, the more severe the effects of malfunctions from a leaky exhaust. Since catalytic converters or particle filters create a high dynamic pressure in modern drives, leaky components in front of these units are particularly noticeable. The electronics cannot process the resulting measured values correctly, performance often drops drastically, and consumption increases considerably. You should therefore always think of a possible hole in the exhaust if there is a loss of performance or increased fuel consumption.
