- Engine power - what is it?
- How to calculate motor power (kW)?
- Rated power of an internal combustion engine - how is it given?
- The power plant of electric motors and internal combustion engines and the influence of revolutions
- What more do you need - hp. or Nm?
The most important numerical parameters of the car are engine power and power. What is the difference between these concepts? Strength shows how objects interact with each other. Its unit is newtons. Power, on the other hand, shows the ratio of work to the time it takes to do it. In engines, these values have a huge impact on the rotation of the unit. How to calculate engine power? KW is the unit that will be useful. We present the nuances and suggest how to calculate the power of the drive unit!
Engine power - what is it?
It is often said that a car with some kind of engine has 100 or 150 horsepower. However, these units are not part of the SI system of units and must be calculated from kilowatts (kW). Therefore, in the vehicle data sheet you will find information on how many kW the engine has, and not horsepower. Engine power is the amount of work and is measured on the drive shaft of the unit or on the wheels (for example, on a dynamometer). Naturally, a measurement directly on the engine will give a slightly higher value. In addition, this is not a constant value, as it depends on the turnover.
How to calculate motor power (kW)?
To calculate the motor power in kW, two values are needed:
- engine speed.
Let's say you want to buy an engine that develops 160 Nm of torque at 2500 rpm. To get the power in kilowatts, you need to multiply these values \u9549,3b\u41,88band divide by 1,36. What value will you get? It turns out that the engine at this point of rotation produces a power of 57 kW. Multiply the result by XNUMX to get the value in km. This gives approximately XNUMX hp.
Rated power of an internal combustion engine - how is it given?
Rated power expresses useful power. It is always measured on the drive shaft of the engine, and in the case of internal combustion engines it is indicated in kW or hp. Please note that engine power is not a constant value. It largely depends on the engine speed and torque. That is why, for example, gasoline and diesel units have extremely different performance characteristics, and it makes no sense to screw the first one to high speeds. How to understand it?
The power plant of electric motors and internal combustion engines and the influence of revolutions
Let's go back to the definition of torque. This is the force expressed in newtons. It talks about changing the position of a body of a certain mass with a certain acceleration. Diesel engines have more torque in the lower rpm range. They often reach their maximum value in the range of 1500-3500 rpm. Then you feel something like being pressed into a chair. This is a kind of sequence that decreases as turnover increases beyond this limit.
Power and torque of gasoline engines
Gasoline engines are completely different, although with the use of turbochargers, these differences are erased. They often reach their maximum torque around 4000-5500 rpm. That is why naturally aspirated gasoline units have the greatest engine power in the upper parts of the revolutions and so rush into it.
What more do you need - hp. or Nm?
You may have noticed that car descriptions usually contain information about the power of a particular engine. These are very often round and very "beautiful" numbers. For example, individual VAG diesel units at one time had 90, 110, 130 and 150 hp. This helped boost interest in individual vehicles dramatically. However, in everyday operation, for efficient movement, the most important thing is not the power of the engine, but its torque. Dlaczego?
Why does torque sometimes say more than engine power?
The flexibility of the unit depends on how many Nm a given engine has and in what speed range it produces its maximum value. That's why small engines are equipped with turbochargers. Due to this, they do not need to be kept at high speeds in order to obtain the appropriate operating parameters. This feature is useful when you are heavily loaded, such as when driving with a lot of luggage, overtaking or driving uphill. Then it is clear that small gasoline engines must be kept within 3-4 thousand. rpm for smooth operation. Diesels, on the other hand, don't need that much RPM to handle tougher conditions well. When choosing a car, pay attention not only to how much horsepower a given model has. See also in what range it develops power and torque. It happens that two units with the same power have completely different performance characteristics, because they operate in a different speed range. So remember that engine power isn't everything. Fast and widely available torque is what is important for efficient movement.