What should be the optimum operating temperature of the engine
We have already talked about how dangerous an engine overheating is. In short, at excessive temperature and the accompanying expansion of the metals from which the engine parts are made, the gaps provided for by its design are leveled, and the friction pairs begin to mechanically act on each other, producing scoring and, ultimately, leading to jamming.
On the other hand, an engine that has not reached operating temperature is unable to work efficiently: burn fuel completely, develop the dynamic and power characteristics laid down by its creators. We also wrote about how important it is to warm up the car - it remains only to determine the temperature range, “comfortable”, that is, optimal for an automobile engine.
WHAT IS WORKING TEMPERATURE
It is known that in the working chambers of internal combustion engines, temperatures of 1000 ° C and above are not uncommon, and therefore the parts in contact with them - pistons, valves - can heat up to 400 degrees or more. However, under the operating temperature of the internal combustion engine, they do not understand these values, but the heating of the standard cooling system - it is it that protects the motor from overheating, which causes thermal deformation.
The main types of cooling systems for internal combustion engines:
Air cooling. The motor is cooled by air flows, the surface is equipped with additional metal fins - a radiator, for better heat dissipation. Sometimes a fan is used to force additional air. It is rarely used in cars, more in two-stroke motor vehicles.
liquid cooling. It occurs by placing the cylinders inside the hydraulic shell - the "shirt", in which the coolant circulates, driven by a water pump. Additional cooling takes place in a radiator located in the front of the car, from oncoming air flows and with the help of a fan that rotates constantly or turns on when the temperature rises.
Despite the fact that research in the field of thermodynamics back in the 19th century proved that the efficiency of an internal combustion engine increases with an increase in operating temperature, designers are forced to coordinate its value with the parameters of the substance that cools the engine. Air-cooled engines have the highest operating temperatures - their radiators can reach 200°C or more. The smallest - for ship engines cooled by outboard water.
The engines of modern cars are predominantly equipped with a liquid cooling system - firstly, it is the most stable, and secondly, with its help it is easier to implement interior heating and attachment heating schemes, as well as relevant engine temperature control. Its other name is the water system, and for good reason. For a long time, before the invention of non-freezing antifreeze, ordinary water was used as a coolant.
It was from its parameters that engine designers were repelled when they calculated the operating temperature of engines, which was the case for carburetor engines used in the past. Boiling water occurs at 90-100°C, depending on the pressure of atmospheric air, so the operating temperature of the coolant in most engines is still considered to be 85-90 degrees.
WORKING TEMPERATURE OF MODERN ENGINES
Meanwhile, the efficiency of the internal combustion engine, which is directly proportional to its operating temperature, consists not only in increasing power, but also in reducing harmful emissions. Therefore, as special coolants with extended temperature characteristics were invented, the operating temperature indicators began to increase structurally.
Ideally, an engine coolant should solve several problems:
do not freeze at negative ambient temperatures;
boil at a higher temperature than water;
be chemically neutral to the materials of the parts with which it comes into contact (metal, rubber, plastic).
In addition to the low boiling point, the use of water for cooling had a number of disadvantages: it contributed to the corrosion of metal engine parts and the deposition of salts in the cooling system. The first antifreezes (non-freezing coolants) were created back in the 20s of the twentieth century from a mixture of water and glycerin, in a ratio of approximately 1 to 2. The liquid had excellent temperature characteristics, froze at -40 and boiled at 290 ° C, but had a very poor fluidity, respectively, poorly and slowly moved through the system.
They tried to solve the problem with the help of ethanol, methanol, salts and other methods, but dihydric alcohols became a full-fledged replacement for glycerin: first ethylene glycol, and much later propylene glycol. It is on their basis that all modern antifreezes are produced. It is curious that in its pure form, the temperature characteristics of these alcohols are very modest, but if you add water to them, they improve significantly.
Although the emphasis (and this is evident even from the name - antifreeze) was placed more on the non-freezing properties of the liquid, the boiling point of dilute ethylene glycol also turned out to be higher than that of water - on average
eat, 110-115°C. Therefore, even late carburetor engines, developed in the 70s and 80s, already had an operating temperature of more than 100 degrees, that is, they could only use antifreeze as a coolant. With the growth of environmental requirements, the equipment of cars with catalysts, electronic sensors, as well as the improvement of the quality of antifreezes, the operating temperature continued to rise.
Today, engines are not uncommon, where an operating temperature of 120-130 ° C is acceptable - however, mainly at idle, it decreases in motion. However, this situation imposes increased requirements on operating conditions - first of all, the serviceability of all vehicle systems.
HOW TO KEEP THE ENGINE TEMPERATURE OPTIMUM
Temperature suicide: why modern engines are doomed to overheat
The higher the operating temperature of the engine, the more difficult it is to keep the engine from overheating. You need to start with preventive measures:
constant monitoring of the level and condition of the coolant;
regular and timely replacement of the coolant;
control of work and timely replacement of the pump (when replacing the timing belt or chain, according to the operating instructions);
thermostat control;
visual inspection of pipes, clamps, cooling radiator and heater for leaks.
In addition, it is necessary to constantly monitor other engine systems that can affect its temperature: ignition systems, carburetion, exhaust system. To do this, it is advisable to purchase an OBD scanner that shows errors that occur during the operation of the computer, as well as the temperature in different parts of the internal combustion engine: for example, the intake manifold. By the nature of the errors, you can determine which of the nodes you need to pay attention to.
