Basic Parameters Of The Engine

The basic parameters of a car engine mainly include the number of cylinders, arrangement of cylinders, valves, displacement, maximum output power, and maximum torque.
Number of valves
Most domestic engines use two valves per cylinder, one intake valve and one exhaust valve; Foreign car engines generally adopt a 4-valve structure per cylinder, which includes 2 intake and 2 exhaust valves, improving the efficiency of intake and exhaust; Some foreign companies have started to adopt a 5-valve structure per cylinder, which includes 3 intake valves and 2 exhaust valves. The main purpose is to increase the intake volume and make combustion more thorough. The more valves there are, the better. A 5-valve engine can indeed improve intake efficiency, but its structure is extremely complex, difficult to process, and it is rarely used. The domestically produced New Jetta King uses a 5-valve engine.
Arrangement of cylinders
Generally, the cylinders of engines with less than 5 cylinders are arranged in an inline manner, and a few 6-cylinder engines also have an inline arrangement. The cylinder block of an inline engine is arranged in a straight line, with a simple structure of the cylinder block, cylinder head, and crankshaft, low manufacturing cost, good low-speed torque characteristics, low fuel consumption, compact size, and wide application. The disadvantage is low power. The dynamic balance of the inline 6-cylinder is good, and the vibration is relatively small. Most 6 to 12 cylinder engines adopt a V-shaped arrangement, which means that the cylinders are arranged in four staggered angles. The shape is compact, and the length and height dimensions of the V-shaped engine are small, making it very convenient to arrange. The V8 engine has a very complex structure and high manufacturing cost, so it is rarely used. The V12 engine is too large and heavy, and only a few other high-end sedans use it.
Number of cylinders
The commonly used cylinder numbers for automotive engines are 3, 4, 5, 6, and 8. Engines with a displacement of less than 1 liter typically have 3 cylinders, while 2.5-liter engines typically have 4 cylinders. Engines with a displacement of around 3 liters typically have 6 cylinders, while engines with a displacement of around 4 liters typically have 8 cylinders. Engines with a displacement of over 5.5 liters typically have 12 cylinders. Generally speaking, under the same cylinder diameter, the more cylinders, the larger the displacement, and the higher the power; At the same displacement, the more cylinders there are, the smaller the cylinder diameter, and the higher the rotational speed, thereby obtaining a greater increase in power.
Exhaust volume
The working volume of a cylinder refers to the volume of gas swept by the piston from top dead center to bottom dead center, also known as the single cylinder displacement, which depends on the cylinder diameter and piston stroke. The engine displacement is the sum of the working volumes of each cylinder, usually expressed in liters (l). Engine displacement is one of the most important structural parameters, which better represents the size of the engine than cylinder diameter and number. Many indicators of the engine are closely related to the exhaust volume.
Maximum torque
The torque output from the crankshaft end of the engine is expressed in N.m/r/min, and the maximum torque generally occurs in the range of middle and low engine speeds. As the speed increases, the torque will actually decrease. Of course, when choosing, it is important to weigh how to use existing functions reasonably and not waste them. For example, it is necessary to turn on air conditioning in both winter and summer in Beijing, and when selecting engine power, one should consider not being too small; There is no need to pick up a high-power engine just for commuting on the city ring road. Try to achieve economical and reasonable engine selection.
Maximum output power
The maximum output power is generally expressed in horses (ps) or kilowatts (kw). The output power of the engine is closely related to the speed. As the speed increases, the power of the engine also increases accordingly. However, after reaching a certain speed, the power actually shows a downward trend. In general, the maximum output power is expressed in revolutions per minute (r/min) in the instructions for car use, such as 100ps/5000r/min, which means the maximum output power is 100 horsepower at 5000 revolutions per minute.