You will need

- the data sheet of the machine;
- knowledge about the structure of the engine

Instruction

1

To determine the amount of

**engine**and correctly calculate, you need to know how, in principle, arranged in the motor vehicle. The task**engine**is to convert thermal energy produced by the combustion process in the cylinders, into mechanical energy which, in fact, allows the machine to move.2

Cylinders in avtodvigatel ' several. They are placed in a single unit, within which further installed the pistons. And that's all this system determines your job is the volume of the motor. To calculate it, despite the apparent complexity, is quite simple. You need to know the technical parameters of "stuffing", that is cylinders and pistons, and then to assume a particular mathematical formula.

3

The formula used to calculate the volume

**of the engine**, for example, for the four machines, as follows: V = 3,14 x N x D squared / 1000 (is the number of revolutions per minute at low and medium figures). In this formula the value of D determines the diameter of the piston**of the engine**, specified in millimeters, and H is the piston stroke in millimeters. For example, in cars the diameter of the piston is equal to 82.4 mm and stroke is 74,8 mm, then the V**of the engine**it will have the following: 3,14 x 74,8 x 82,4 82,4 x / 1000 = 1595 cubic centimeters. Accordingly, the capacity of this machine is average.4

Volume is always either in cubic inches or in liters. Defining the working volume

**of the engine**, we can safely classify all car groups: mini (volume of 1.4 liters), Audi (1.2-1.7 liters), sredneetazhnye (1,8-3,5 liters) and krupnosortnyj (over 3.5 litres). In most countries in the world indicators of the volume**of the engine**depends on the taxation and insurance. For example, in some European countries for more powerful cars (those that have a working volume**of the engine**more than 2,000 cubic centimeters) is assumed to be paying higher tax.# Advice 2 : How to calculate compression ratio

One of the parameters adjusted by the engine –

**the degree****of compression**. The value of this indicator is closely linked to power, detonation resistance, cost effectiveness and other such salient features of the engine. In view of this, it is important to calculate the compression ratio.You will need

- calculator;
- - burette;
- glass;
- sealant.

Instruction

1

The compression ratio is defined as the ratio of the full volume ofa cylinder of the internal combustion engine to the volume of the combustion chamber. Expect this figure according to the following formula: CR=(V + C)/C, where V is the working capacity of cylinder – volume of the combustion chamber.

2

To find the capacity of one cylinder, needs engine capacity (displacement) divided by the number of cylinders. For example, if the displacement four-cylinder engine is equal to 1200 cubic centimeters, the capacity of one cylinder is equal to 300 cubic centimeters.

3

The capacity of the combustion chamber is the volume that remains above the piston when the latter is at top dead center. It includes several variables: the volume of the cavity in the head, a cut (in the bottom of the piston), the volume between the upper part of the piston unit and the upper part of the cylinder Assembly while the piston in the top dead point and the volume equal to the thickness of the strip.

4

If the gasket is round, the amount equal to its thickness, determined by the formula: Vcc=[(p*D2*L)/4]/1,000, where p=3,142, where L is the thickness of the gaskets in the clamped condition (in mm), D is the diameter of the holes in the gasket (in mm). If the gasket is not round, then measure the volume at the burette. To do this, glue the gasket with sealant to the glass, then place glass on a flat surface and fill with water the hole in the gasket, using a burette.

5

Knowing the working capacity of the cylinder and the combustion chamber volume, substitute these values into the formula and calculate the compression ratio.

6

Thermal efficiency is directly related to the compression ratio: the higher the compression the less fuel used by an engine to generate the required power.

Note

In any case, do not modify independently the combustion chamber because they may interfere with the processes of displacement!

Useful advice

The efficiency of diesel engines is largely due to typical values of compression ratio: the value of this indicator may vary from 18:1 to 22:1.