Each engine, regardless of volume, type of fuel, power and torque, has a number of technical characteristics that do not change over time. For example, when worn, the engine develops less power than a new torque. In addition, fuel consumption also increases . But there are others, such as piston diameter, stroke, displacement. So, among such quantities one can find the degree of compression. This is a calculated value.
So, you need to find out what is the degree of compression. This is the ratio of the working volume of one engine cylinder to the volume of the combustion chamber. Therefore, if the car owner wants to increase the compression ratio, there are two ways to do this: reduce the second (i.e., combustion chamber) or increase the first (i.e., cylinder volume). The second way is much more complicated, so tuners prefer to perform all kinds of operations with the cylinder head. This is done by grinding the plate, as the head is solid, and the filling method is not suitable here. In addition, in most engines, the distribution of the combustible mixture in the cylinder is calculated, so a violation of the internal geometry is fraught with consequences.
The degree of compression of the engine affects many of its characteristics in everyday use. First of all, this is its torque, since the higher the pressure above the piston, the more energy it receives during the stroke. As a result, the pressure on the neck of the crankshaft increases, which means that the engine torque is also increased.
Another characteristic that is directly affected by the compression ratio is fuel consumption, and this dependence is inversely proportional, that is, the larger the first, the smaller the second. But not all fuels can be used with a high degree of compression. For example, if the degree exceeds 9.0, then gasoline should be with an octane rating of at least 92 (AI-92). The fact is that the low octane number of gasoline indicates its instability to detonation, that is, premature ignition from pressure and temperature.
This leads to increased wear of the connecting
rod-piston group, since the explosion of the mixture occurs even before the piston reaches the top dead center. This reduces engine power. In addition, the temperature regime increases, which is fraught with other, even more terrible consequences, such as burning rings to cylinders.
The compression ratio of a diesel engine is much higher, it happens even twice. It reaches 16, since the ignition of the combustible mixture does not come from an ignition spark, but from the pressure in the combustion chamber. Pistons here have special sleeves in the bottom, which serve to direct the mechanism straight down.
In conclusion, it is worth recalling again what compression ratio is. This is a characteristic of the engine, which does not change throughout the entire operation period, since the dimensions remain the same. Many confuse compression ratio with compression in the engine. We will not go into details about what compression is, let’s just say that it is the pressure that is measured using a pressure gauge. Our compression ratio can only be calculated. In order to do this, you need to measure the volume of the combustion chamber. This is done by adding liquid from a beaker with a division of 1 ml.