Horsepower is a unit of measurement that does not have a single standard in the world, although most countries adhere to one of its numerical values. Horsepower is not included in the generally accepted International System of Measurement, and its official use was canceled in Russia. Meanwhile, this measure is used not only in everyday life, but also at the state level.

What is measured in horsepower

In horsepower, that amount mechanical work, which is produced for a certain period of time. The most common indicator is kilograms per meter per second. It is used mainly in relation to vehicles and some other mechanisms.

In Russia, the tax on transport is calculated on the basis of one horsepower, and in documents for vehicles equipped with an engine, this unit of measurement is often used to indicate its power.

What is horsepower

This measure was introduced in the late 18th century in England. Technological progress and widespread use steam engines identified the need for a common standard for determining their performance.

Using the method of practical measurements made during the work performed by a live horse under certain conditions, he calculated that in 1 second 1 horse is able to move a load weighing 75 kg over a distance of 1 meter - this indicator was taken as one horsepower.

Power standard units

In the International System of Measurement, the official unit for determining power is Watt (1 kilowatt = 1000 watts). This measure will be the same throughout the world.

Watts measure power as the rate of energy transmitted or as the amount of work produced over a specified time.

In connection with the unified world standard, many manufacturers of cars, as well as other vehicles and mechanisms, indicate engine power in watts in the documents for equipment. However, in our country, each horsepower in a car affects the amount of transport tax, so it is more convenient to know the power level of your car's engine in these units.

Metric horsepower

The most common calculation of horsepower (HP) in the world occurs in the metric system. For the calculation, kilogram indicators of the weight of the load are used, and the distance over which it is moved is measured in meters.

In this case, one horsepower is equal to 735.49875 watts, which is equivalent to 0.74 kW.

One kilowatt will be equal to 1.36 liters. With.

Horsepower table

Knowing the calculation formula, you can easily translate digital indicators from one measurement unit to another, but if you do not want to engage in calculations, you can use a comparison table. The numbers below are valid for metric measurements.

The difference in the calculation of horsepower in America and the UK

Due to the use in a number of countries, for example, in the USA and Great Britain, feet and pounds as measures of length and weight, their calculation of horsepower will differ from that adopted in most of the world states, including Russia.

In the traditional system of measurement of these countries, one horsepower would be equal to 745.6999 W (0.746 kW) and equal to 1.014 metric horsepower. Equal in this unit of measurement will make cars that are judged using feet and pounds more powerful in actual operation.

However, in most cases, the engine power in the accompanying documents is indicated in kW, so it can be recalculated using the standard formula.

Often, real power indicators differ from factory parameters and it makes sense to make real measurements:

• putting the car on a dynamometer is the most accurate type of diagnostics;
• by installing additional electronic equipment into it (which is advisable only for vehicles that need constant monitoring of this indicator, since maintenance and purchase of special equipment will not be cheap);
• or by checking with an application downloaded to a laptop, which is connected to the car via a cable and takes measurements during test drives.

Features of determining the gross and net engine power

Thanks to a kind of engine power metering system used in factories that produce vehicles in Japan and some belonging to the United States, the amount of horsepower in cars manufactured by them differed from the actual one during operation.

It's about the so-called net power and gross power. When measuring the first indicator, the energy consumption for the operation of related units is taken into account - the cooling system, generator, drive belts. Their influence is not taken into account in gross power calculations. Therefore, the real indicators at different ways measurements can differ significantly - by 10-25 percent.

Cars in the documents of which the engine power is prescribed based on the gross indicator will be weaker than cars with identical digital values ​​of net measurements.

Since in Russia the amount of tax paid for it depends on the amount of horsepower in a vehicle, it is better to find out the real performance of the engine in order to avoid overpayment, which in certain cases can be very significant. Especially if you have to not only add non-existent horsepower to pay at the same rate, but also multiply their total amount by the increased rate (this can happen if the theoretical and actual indicators are in different price groups for calculating the transport payment, for example, according to documents 155 liters. from., and in fact less than 150, etc.).

Story

There are several units of measurement in the world called "horsepower". In European countries, Russia and the CIS, as a rule, under horse power refers to the so-called "metric horsepower", equal to approximately 735 watts (75 kgf · m / s).

In the automotive industry in the United Kingdom and the United States, HP is most commonly used. equates to 746 watts, which equals 1.014 metric horsepower. Electric horsepower (746 W) and boiler horsepower (9809.5 W) are also used in industry and energy in the United States.

In practice, and this is obvious. But how can you calculate the engine power of a car in another way? It's very simple: if you want to find out how much horsepower is in a car engine, you connect the engine to a special dynamometer. A dynamometer puts a load on the motor and measures the amount of energy that the motor can develop against the load. But, nevertheless, in order to calculate the engine power, there is one more step that must be overcome, and we will talk about this now.

Torque

Imagine that you have a large socket wrench with a handle on it 1 meter long, and you push on it with a weight of 100 grams. What you do is called an application, which also has its own unit of measurement, and in this case it is calculated as 1 Newton * meter (N * m), because you are pressing 100 grams (which is approximately equal to 1 Newton) with a "shoulder "1 meter. You can get the same 1 N * m if, for example, you push with a weight of 1 kg on a socket wrench with a handle length of 10 cm.

Likewise, if you attach a motor shaft instead of a socket wrench, the motor will give some torque to the shaft. A dynamometer measures this torque. And then you can easily convert torque to horsepower using a simple formula and thus calculate the power of the car. This formula looks like this:

Engine power = (Revolutions per minute * Torque) / 5252.

You can get an idea of ​​how a dynamometer works as follows: Imagine turning on the car engine while the neutral gear and press the accelerator pedal to the floor. The engine will run so fast that it could explode. This is not good, but so, using a dynamometer, you can measure the engine torque at different speeds. You can connect the engine to a dynamometer, step on the gas pedal and put enough load on the dynamometer to keep the engine running at, say, 7,000 rpm. You write down on paper what maximum load the engine can handle. Then you start applying additional load to bring down the engine speed to 6,500 rpm and record the load again in the new mode. Then you load the engine down to 6,000 rpm, and so on. You can do the same down to the critically low 500 or 1,000 rpm. What dynamometers do is actually measure torque and then convert torque to horsepower to calculate horsepower.

Nevertheless, the torque, although it grows with the power with increasing revs, nevertheless, the power value is not always directly proportional to the torque. So, e If you plot power and torque against engine rpm, making marks in 500 rpm increments, what you end up with is the engine power curve. A typical power curve for a high-performance engine might look like this (in the example, a 300-horsepower Mitsubishi engine 3000):

This graph indicates that any engine has a peak power that can be calculated by a dynamometer - the RPM value at which the engine's power reaches its maximum. The engine also has a maximum torque in a specific rpm range. You will often see a statement like "123 HP @ 4,600 rpm, 155 Nm @ 4,200 rpm" in vehicle specifications. And also, when people say that the engine is "low-speed" or "high-speed", they mean that the maximum torque of the engine is achieved at a rather low or high speed, respectively (for example, by their nature they are low-speed, and therefore (but not only because) they are often used on trucks and tractors, but gasoline engines, on the contrary, high-speed).

How to determine engine power

How is engine power calculated?

The horsepower of a car engine is not measured by horses in practice, and this is obvious. But how can you calculate the engine power of a car in another way? It's very simple: if you want to find out how much horsepower is in a car engine, you connect the engine to a special dynamometer. A dynamometer puts a load on the motor and measures the amount of energy that the motor can develop against the load. But, nevertheless, in order to calculate the engine power, there is one more step that must be overcome, and we will talk about this now.

Torque

Imagine that you have a large socket wrench with a handle on it 1 meter long, and you push on it with a weight of 100 grams. What you do is called applying torque, which also has its own unit of measurement, and in this case it is calculated as 1 Newton * meter (N * m), because you are pressing 100 grams (which is approximately equal to 1 Newton) with "shoulder" 1 meter. You can get the same 1 N * m if, for example, you push with a weight of 1 kg on a socket wrench with a handle length of 10 cm.

Likewise, if you attach a motor shaft instead of a socket wrench, the motor will give some torque to the shaft. A dynamometer measures this torque. And then you can easily convert torque to horsepower using a simple formula and thus calculate the power of the car. This formula looks like this:

Engine power = (Revolutions per minute * Torque) / 5252.

Nevertheless, the torque, although it grows with the power with increasing revs, nevertheless, the power value is not always directly proportional to the torque. So if you plot power and torque against engine rpm, making marks in 500 rpm increments, what you end up with is the engine power curve. A typical power curve for a high-performance engine might look like this (in the example, a 300-horsepower Mitsubishi 3000):

This graph indicates that any engine has a peak power that can be calculated by a dynamometer - the RPM value at which the engine's power reaches its maximum. The engine also has a maximum torque in a specific rpm range. You will often see a statement like "123 HP @ 4,600 rpm, 155 Nm @ 4,200 rpm" in vehicle specifications. Also, when people say that the engine is "low-speed" or "high-speed", they mean that the maximum torque of the engine is achieved at a rather low or high speed, respectively (for example, diesel engines are inherently low-speed, and therefore (but not only for this reason) they are often used on trucks and tractors, but gasoline engines, on the contrary, are high-speed).

howcarworks.ru

Many people, buying a car or thinking about engine power, look at the value of "horsepower", and not at all at the torque indicator and its maximum value. Nevertheless, for far-sighted drivers, this feature of the engine, which makes it possible to joyfully accelerate and, as a result, deftly maneuver, is also very important. What do you need to know about this characteristic, what does it depend on and the car with which torque is better?

By definition, the moment of force is a physical quantity calculated as the product of the radius vector, which has a starting point on the axis of rotation, and the final point at the point of application of the force, by the vector of this force. This is a concept that characterizes the rotational action of a force directed at a rigid body. The torque in a car engine is determined by multiplying the force acting on the piston by the distance from the central axis of the connecting rod neck to the crankshaft, more precisely, its central axis. This is the thrust characteristic, the moment of force, for information, is measured in Newton meters.

Machine power and engine torque are closely related. Getting into the car and following the highway, the driver finds out that the ability of the engine to produce good dynamics at the lowest rpm is of paramount importance. After security, of course. The speed and dynamics of acceleration of the car depend on the engine power, well-known horsepower. Power is calculated by multiplying the torque by the shaft speed. Accordingly, there are two ways to increase it: to increase the torque or the shaft speed. Increase this frequency at piston engine not easy: the forces of inertia (in terms of the square of revolutions), loads on the structure, friction (tens of times) affect. Each engine on the graph will have an inflection point where the torque, after a short increase, decreases, since when operating at high power, the filling of the cylinders with a mixture of fuel and air deteriorates. Another way: increase the torque. Here, boost is needed in order to pump twice as much air and fuel through the engine. Then the torque will approximately double at the same speed. But in this case, thermal loads increase, hence other problems.

If we take an average car, then all the forces will be involved only at 5000–6500 rpm. And with normal driving around the city, with low revs, in 2-3 thousand, the car is driven by only half of the horsepower. And only when performing a high-speed maneuver on the track, at high revs, the full power of the motor will manifest itself. Moreover, it is clear to anyone that the faster the engine picks up speed, the earlier the car will accelerate. The torque is directly proportional to the length of the connecting rod. That is, the longer it is, the higher the torque.

It often seems to a person that if he has so much horsepower under the hood, then they all work for him every second. But no! Let's say there is a car, the maximum engine power of which will be at 5000–6500 rpm. That is, for sufficient acceleration, you will have to accelerate the motor and increase the rpm. This will be possible only after a certain time, which can be very important when overtaking. In the case of a powerful motor with normal torque, when the required power appears already at 2000 rpm, we get instant acceleration for any risky maneuver.

The difference in torque in a small car gasoline or diesel engine

It is generally accepted that almost all subcompact cars with "high-torque" engines, as well as cars with diesel engines... Drivers of diesel vehicles especially notice fast acceleration even at low revs. When they boast, they often say that in him, in the torque, all the power is. Now it is clear: torque is not less than horsepower, important characteristic iron horse. It should be looked at first and foremost when buying a new car, as well as when selecting a used one.

Dependence of engine speed on torque

So it became clear what the same 200 Nm at 1700 rpm. better than the same 200 at 4000 rpm. Now it is clear that it is the torque that affects the agility and acceleration of the car. This is noticeable in the time during which you can accelerate further. Of course, it's great to invent a car, whose engine torque at any speed, whether low, medium or high, is stable and would be as close to the peak as possible. It's a pity, but such an ideal option does not exist yet. This is from the realm of fantasy.

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Determining the power of a car: how to calculate?

It is customary to refer to the horsepower as the dimensional unit of power. Initially, this concept was introduced by a Scottish engineer solely to compare the power indicators of steam engines with the power in horses. This parameter is used to calculate the power of absolutely any car. This value is indicated in the documents for the car. However, now the power of the vehicle is indicated in a completely different dimensional value of kWh. Currently, the dimensional value in the form of horsepower is somewhat outdated and has lost its relevance. Although large automobile concerns use it to determine power, they are increasingly using the definition in kilowatts. In this case, the power can be calculated again in horsepower. How to do this and what is needed to carry out such a procedure, we will try to describe in detail in this article.

What is needed to calculate the power?

To calculate the horsepower of a car, you must first of all have a car and a service station. For such a procedure, it is recommended to use the Russian system measurements as with European systems some inconsistencies may occur during counting. For them, it is customary to equate 1 horsepower to 75kgm / s. In other words:

1 hp = 75 kgm / s

where 75 is the power to lift a load weighing at a height of 1 m in 1 second.

In addition, horsepower can be converted into another dimensional unit of kilowatts. It looks like this:

1 HP = 735.5 W (0.735 kW)

Moreover, in this case, the maximum speed developed by the car will be called the boiler horsepower.

Find out the value of power: how to do it?

To find out the value of the vehicle's power, the driver needs to translate all the listed parameters. This can be done using the translation formulas. You can find out the power of the car in the car passport. If in the data sheet the power value is indicated in kW, then to calculate the horsepower, this value only needs to be divided by 0.735. The resulting figure will be the exact designation of the power specifically for this car brand in horsepower.

Service station: how to calculate the power of a car with its help?

One of the most simple ways power calculation is considered to be a visit to a technical inspection station. Most modern stations have special equipment allowing you to quickly calculate the amount of power.

The computer can easily determine the amount of horsepower. In the workshop, this is done as follows:

• A car is driven onto the platform;
• The car starts up and the gas pedal is squeezed out all the way;
• Let the car run for a couple of minutes.

The computer installation is capable of performing all the necessary measurements in a few minutes. After that, the motorist will receive the most accurate results.

automend.ru

How to measure engine power

After a while, some car owners do not want to drive on standard car... That is why they switch to tuning their vehicle, which consists in certain changes. technical design in order to achieve an increase in the vehicle's capabilities as a result. But, even after upgrading, you need to know how powerful the car has become. You will learn how the engine power is measured later.

To measure engine power, you need a computer, a special program, a cable, and a dynamometer.

There are several methods for measuring the power of a car engine. It should be noted that they are all inaccurate, that is, they have some error. You can install special electronic equipment that monitors changes in engine operating parameters in online mode.

This equipment has a moderate degree of error. But it has a disadvantage in the form of high cost. In addition, the installation of this equipment requires specialists, whose services are expensive. Maintenance of expensive equipment can significantly exceed the cost of Maintenance car. The use of this equipment is advisable only if you have a sports car that requires constant monitoring.

In addition, there are less expensive options for determining the power of your vehicle. This requires a computer with a special cable and software to measure the torque. This program should have instructions for use. It must be carefully studied, since the sequence of all actions is described in detail there. Locate the connector to diagnose your car. You need to remove the plug from it, connect the laptop, download the application. Next, you need to ride several times at different speeds. The application will remember these indicators, then the power of your motor will be automatically calculated, and the errors in the calculations will also be indicated.

The most accurate way to measure engine power is to mount the vehicle on a dynamometer. For these purposes, you need to use a service that has such settings. You need to drive your car with the front end to the fan on the stand. The wheels must be placed exactly between the two drums. Fasten special belts to the supporting structure of the car and connect the equipment to the car using the diagnostic connector.

On the exhaust pipe you need to put on a corrugated frame that removes gas from the box. Then you need to turn on the fan to simulate the resistance from the oncoming air, and accelerate your car to the maximum. In parallel, you need to monitor the condition of the connecting belts. You should try several times to eliminate the possibility of error. At each attempt, the computer will produce a printout indicating maximum speed as well as power.

avtooverview.ru

Engine torque and power - what is it?

How can the same engine have different kickbacks? What is the difference between power and torque?

WHAT IS HORSE POWER?

How much strength do you have? - such a question has been heard by anyone who has ever touched the world of cars. It is not even necessary to explain to anyone what forces are actually meant - horse forces. It is in them that we are used to assessing the power of the engine, one of the most important consumer characteristics of the car.

Already, there is practically no horse-drawn transport left even in the villages, and this unit of measurement has been alive and well for more than a hundred years. But horsepower is, in fact, illegal. It is not included in the international system of units (I think many remember from school that it is called SI) and therefore does not have an official status. Moreover, the International Organization of Legal Metrology requires the removal of horsepower from circulation as soon as possible, and the EU directive 80/181 / EEC of January 1, 2010 explicitly obliges automakers to use traditional "hp" only as an auxiliary quantity to indicate power.

But it is not for nothing that habit is considered second nature. After all, we say in everyday life "copier" instead of a copier and call the adhesive tape "scotch tape". Here are the unrecognized "hp" now they are used not only by ordinary people, but also by almost all car companies... What do they care about recommendation directives? Since it is more convenient for the buyer, so be it. Why are there producers - even the state is following the lead. If anyone has forgotten, in Russia transport tax and the OSAGO tariff is calculated from horsepower, as well as the cost of evacuating an incorrectly parked vehicle in Moscow.

And no one would find fault with this, if not one weighty "but". Conceived to make life easier for us, horsepower is actually confusing. After all, it appeared in the era of the industrial revolution as a completely conventional value, which, not only to a car engine, even to a horse, has a rather indirect relationship. The meaning of this unit is as follows - 1 hp. enough to lift a 75 kg load to a height of 1 meter in 1 second. In fact, this is a highly average performance indicator for one mare. And nothing more.

In other words, the new unit of measurement was very useful to industrialists who extracted, for example, coal from mines, and manufacturers of related equipment. With its help, it was easier to assess the superiority of mechanisms over animal power. And since the machines were already driven by steam, and later by kerosene engines, the "hp" passed by inheritance to self-run crews.

Ironically, horsepower was invented by a man named after the official unit for measuring power - James Watt. And since the watt (or rather, in relation to powerful machines, kilowatt - kW) by the beginning of the 19th century was also actively included in the turnover, it was necessary to somehow bring the two values ​​to each other. This is where the key disagreements arose. For example, in Russia and most other European countries, they have adopted the so-called metric horsepower, which is equal to 735.49875 W or, which is more familiar to us now, 1 kW = 1.36 hp. Such "hp" most often they denote PS (from the German Pferdestärke), but there are other options - cv, hk, pk, ks, ch ... At the same time, Great Britain and a number of its former colonies decided to go their own way, organizing an "imperial" measurement system with its pounds, feet and other delights, in which the mechanical (or, in other words, indicator) horsepower was already 745.69987158227022 watts. And then - off we go. For example, in the USA they even invented electric (746 W) and boiler (9809.5 W) horsepower.

So it turns out that the same car with the same engine in different countries on paper may have different power... Take, for example, the popular crossover Kia Sportage - in Russia or Germany, according to the passport, its two-liter turbodiesel in two versions develops 136 or 184 hp, and in England - 134 and 181 "horses". Although, in fact, the output of the motor in international units is exactly 100 and 135 kW - and anywhere in the world. But, you see, it sounds unusual. And the numbers are not so impressive anymore. Therefore, automakers are in no hurry to switch to the official unit of measurement, explaining this by marketing and traditions. How is it? The competitors will have 136 power, and we have only some 100 kW? No, that will not do…

HOW IS POWER MEASURED?

However, "power" tricks are not limited to playing with units of measurement. Until recently, it was not only designated, but even measured in different ways. In particular, in America for a long time (until the early 1970s), car manufacturers practiced bench testing of engines stripped naked - without a linkage like a generator, an air conditioning compressor, a cooling system pump and with a once-through pipe instead of numerous mufflers. Of course, the motor that had thrown off the shackles easily produced 10-20 percent more "hp", so necessary for sales managers. Indeed, few of the buyers went into the intricacies of the test methodology.

The other extreme (but much closer to reality) is taking indicators directly from the wheels of the car, on the running drums. This is what racing teams, tuning workshops and other teams do, for which it is important to know the return of the engine, taking into account all possible losses, including transmission losses.

But in the end, a compromise option was adopted as a model in various methods such as European ECE, DIN or American SAE. When the engine is installed on a bench, but with all the hitch necessary for smooth operation, including a standard exhaust tract. You can only remove equipment related to other systems of the machine (for example, the air suspension compressor or the power steering pump). That is, the engine is tested exactly in the form in which it actually stands under the hood of the car. This makes it possible to exclude the "quality" of the transmission from the final result and to determine the power at the crankshaft, taking into account the losses on the drive of the main attachments. So, if we talk about Europe, then this procedure is regulated by directive 80/1269 / EEC, first adopted back in 1980 and since then regularly updated.

WHAT IS TORQUE?

But if power, as they say in America, helps cars sell, then torque propels them forward. It is measured in newton meters (N ∙ m), however, most drivers still do not have a clear idea of ​​this characteristic of the motor. At its best, ordinary people know one thing - the higher the torque, the better. Almost like power, isn't it? That's just how, then, "N ∙ m" differ from "HP".?

In fact, these are related quantities. Moreover, power is derived from the torque and rpm of the motor. And it is simply impossible to consider them separately. Know - to get power in watts, you need to multiply the torque in newton meters by the current crankshaft revolutions and a factor of 0.1047. Do you want the usual horsepower? No problem! Divide the result by 1000 (so you get kilowatts) and multiply by a factor of 1.36.

Technically speaking, power indicates how much work a motor can do in a unit of time. But the torque characterizes the potential of the engine to perform this very work. Shows the resistance that he can overcome. For example, if the car rests its wheels on a high curb and cannot move, the power will be zero, since the motor does not perform any work - there is no movement, but the torque develops at the same time. Indeed, for that moment, until the engine stalls from strain, the working mixture burns out in the cylinders, the gases press on the pistons, and the connecting rods try to bring the crankshaft into rotation. In other words, moment without power can exist, but power without moment cannot. That is, it is "N ∙ m" that are the main "product" of the engine, which it produces by converting thermal energy into mechanical energy.

If we draw analogies with a person, "N ∙ m" reflect his strength, and "hp" - endurance. That is why low-speed diesel engines by virtue of their design features we, as a rule, have weightlifters - all other things being equal, they can drag more on themselves and more easily overcome resistance on wheels, albeit not so quickly. But high-speed gasoline engines are more likely to belong to runners - they hold the load worse, but they move faster. In general, there is a simple rule of leverage - we win in strength, we lose in distance or speed. And vice versa.

How is this expressed in practice? First of all, you need to understand that it is the torque and power curves (together, not separately!) On the so-called external speed characteristic engine will reveal its true capabilities. The earlier the thrust peak is reached and the later the power peak is reached, the better the motor is adapted to its tasks. Let's take a simple example - a car is moving on a flat road and suddenly it starts to climb. The resistance on the wheels increases, so that with a constant fuel supply, the revolutions will begin to fall. But if the engine characteristic is correct, the torque, on the contrary, will begin to increase. That is, the motor will adapt itself to the increase in load and will not require the driver or the electronics to switch to a lower gear. The pass is passed, the descent begins. The car started accelerating - high thrust is no longer so important here, another factor becomes critical - the engine must have time to generate it. That is, power comes to the fore. Which can be adjusted not only by the gear ratios in the transmission, but by increasing the engine speed.

It is appropriate here to recall racing car or motorcycle motors. Due to their relatively small working volumes, they cannot develop a record torque, but their ability to spin up to 15 thousand rpm and higher allows them to deliver fantastic power. For example, if a conventional engine at 4000 rpm provides 250 N ∙ m and, accordingly, about 143 hp, then at 18000 rpm it could already produce 640.76 hp. Impressive, isn't it? Another thing is that "civilian" technologies do not always succeed in achieving this.

And, by the way, in this regard, close to ideal performance have electric motors. They develop maximum "Newton meters" right from the start, and then the torque curve gradually drops with increasing revs. At the same time, the power graph increases progressively.

I think you already understood - in the characteristics of the car, not only the maximum values ​​of power and torque are important, but also their dependence on rpm. That is why journalists are so fond of repeating the word "shelf" - when, for example, the engine produces its peak thrust not at one point, but in the range from 1500 to 4500 rpm. After all, if there is a supply of torque, power is also likely to be enough.

Still, the best indicator of the "quality" (let's call it that) of the return of an automobile engine is its elasticity, that is, the ability to gain momentum under load. It is expressed, for example, in acceleration from 60 to 100 km / h in fourth gear or from 80 to 120 km / h in fifth - these are standard tests in the automotive industry. And it may happen that some modern turbo engine with high thrust at low revs and a wide torque shelf gives a feeling of excellent dynamics in the city, but on the highway when overtaking it will turn out to be worse than the ancient atmospheric engine with a more favorable characteristic not only of moment, but also of power ...

So even if the difference between diesel and gasoline units has become more and more vague lately, let alternative engines develop, but the eternal union of power, torque and engine speed will remain relevant. Is always.

Based on materials: auto.mail.ru

Engine torque and power - what is it?

How to determine the engine power of a car

How to determine the power of a car

You will need

• wattmeter, ammeter, voltmeter, screwdriver, knife, wires.

Instructions

The easiest way to determine the power is technical documentation supplied with the appliance. The power of the device is usually indicated on the first pages of such documents. Open the manual (instruction) and find there such words and phrases as power, power consumption, average power, maximum power, etc. The number after them (the range indicated by two numbers through a dash) will be the power of the appliance. The number should be followed by the designation of the power unit: Watt (W), Kilowatt (kW), Milliwatt (MW) or its international designation - Watt, W, kW, mW, if the instruction is not in Russian.

If there are no instructions and other documentation for the electrical appliance, the power can be determined by the inscriptions on the device. As in the above case, be guided by the words denoting power, and by the designation of units of measure of power.

If the device is relatively modern, then information about it is probably available on the Internet. Type in the search engine the name and brand of your appliance. Most manufacturers of household and electronic appliances provide all the necessary information on their official websites. If the information you need cannot be found (this often happens with old or home-made electrical appliances), measure the power using instruments. To do this, de-energize the electrical circuit by turning off the input circuit breaker or circuit breaker. Prepare an open circuit by disconnecting one of the power wires from the input device. Attach a piece of wire to this place, stripping the ends to the desired length. Prepare two pieces of wire of sufficient length. The length of the wires is selected based on the placement of electrical equipment and electrical measuring devices.

Connect the wattmeter to the electrical circuit. Connect the current circuit to the prepared break. Connect the voltage circuit with wires to the input device. Apply voltage by turning on the circuit breaker or switch. Determine the amount of power consumption by the indicator or the scale of the wattmeter.

If there was no wattmeter nearby, then you can get by with a multimeter or a pair of instruments - an ammeter and a voltmeter. To do this, connect an ammeter or a multimeter to a previously prepared break in the electrical circuit. If it is a multimeter, then put it in the current measurement mode. Turn on the breaker or breaker to apply voltage. Write down or remember the current readings on the indicator (scale). Disconnect voltage. Disconnect the ammeter (multimeter) and restore the circuit as it was.

Apply voltage again. Take a voltmeter or put your multimeter in voltage mode. Measure the supply voltage by touching the test leads of the device to the output contacts of the switching device. Remember or write down the measured voltage value. Then calculate the power consumption by multiplying the current value by the voltage value. If the voltage was measured in volts, and the current in amperes, then the power will be obtained in watts (W).

If the electrical appliance is powered from a household power outlet, then the voltage can be omitted and taken equal to 220 Volts (V). If batteries with a known voltage are used for power supply, then voltage measurement can also be omitted.

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note

All operations with electrical equipment (except measurements) should be carried out with a de-energized electrical circuit.

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5 ways to calculate the power of a car engine. Calculator for determining the power of the internal combustion engine online

Consider 5 popular ways to calculate the power of a car engine using data such as:

• engine speed,
• engine volume,
• torque,
• effective pressure in the combustion chamber,
• fuel consumption,
• performance of injectors,
• machine weight
• acceleration time to 100 km.

Each of the formulas that will be used to calculate the power of the car engine is rather relative and cannot determine with 100% accuracy the real horsepower of the driving car. But after making calculations with each of the above garage options, relying on not these or those indicators, you can calculate, at least, the average value, whether it be a stock or a tuned engine, literally with a 10 percent error.

Power is the energy generated by the engine, it is converted into torque at the output shaft of the internal combustion engine. This is not a constant value. Next to the values ​​of the maximum power, the rpm at which it can be achieved is always indicated. The maximum point is reached at the highest average effective pressure in the cylinder (depends on the quality of filling fresh fuel mixture, combustion efficiency and heat losses). Highest power modern motors give out on average at 5500–6500 rpm. In the automotive industry, it is customary to measure engine power in horsepower. Therefore, since most results are displayed in kilowatts, you will need a kW to hp conversion calculator.

How to calculate power through torque

The simplest calculation of the engine power of a car can be determined by the dependence of torque and revolutions.

Torque

The force multiplied by the shoulder of its application, which the engine can give out to overcome certain resistances to movement. Determines how quickly the motor reaches maximum power. Calculated formula of torque versus engine displacement:

Mcr = VHxPE / 0.12566, where

• VH - engine displacement (l),
• PE is the average effective pressure in the combustion chamber (bar).

Engine speed

Crankshaft rotation speed.

The formula for calculating the power of a car's internal combustion engine is as follows:

P = Mcr * n / 9549 [kW], where:

• Mкр - engine torque (Nm),
• n - revolutions of the crankshaft (rpm),
• 9549 is a coefficient in order to substitute revolutions in rpm, and not in alpha cosines.

Since, according to the formula, we get the result in kW, then, if necessary, it can also be converted into horsepower or simply multiplied by a factor of 1.36.

Using these formulas is the easiest way to convert torque to power.

And in order not to go into all these details, a quick calculation of the power of the internal combustion engine online can be done using our calculator.

If you do not know the torque of the engine of your car, then to determine its power in kilowatts, you can also use a formula of the following type:

Ne = Vh * pe * n / 120 (kW), where:

• Vh - engine displacement, cm³
• n - rotation frequency, rpm
• pe - average effective pressure, MPa (for conventional gasoline engines leaves about 0.82 - 0.85 MPa, forced - 0.9 MPa, and for a diesel engine from 0.9 to 2.5 MPa, respectively).

To obtain the engine power in "horses", and not in kilowatts, the result should be divided by 0.735.

Calculation of engine power by air consumption

The same approximate calculation of engine power can be determined by air flow. The function of such a calculation is available to those who have installed on-board computer, since it is necessary to fix the value of the consumption when the car engine, in third gear, is spun up to 5.5 thousand revolutions. Divide the resulting value from the mass air flow sensor by 3 and get the result.

Gw [kg] / 3 = P [hp]

Such a calculation, like the previous one, shows the gross power (bench test of the engine without taking into account losses), which is 10-20% higher than the actual one. It is also worth considering that the readings of the DMRV sensor strongly depend on its contamination and calibrations.

Calculation of power by weight and acceleration time to hundreds

Another interesting way to calculate engine power on any type of fuel, be it gasoline, diesel or gas, is by the dynamics of acceleration. To do this, using the weight of the car (including the pilot) and the acceleration time to 100 km. And in order for the Power Calculation Formula to be as close as possible to the truth, it is also necessary to take into account slip losses depending on the type of drive and the speed of response of different gearboxes. Approximate start losses for front-wheel drive vehicles will be 0.5 sec. and 0.3-0.4 for rear-wheel drive cars.

Using this engine power calculator, which will help you determine the engine power based on the dynamics of acceleration and mass, you can quickly and accurately find out the power of your iron horse without delving into the technical characteristics.

Calculation of the power of the internal combustion engine by the performance of the injectors

An equally effective indicator of the power of an automobile engine is the performance of injectors. Previously, we considered its calculation and relationship, therefore, it will not be difficult to calculate the amount of horsepower using the formula. The estimated power is calculated according to the following scheme:

Where, the load factor is not more than 75-80% (0.75 ... 0.8), the composition of the mixture at maximum performance is about 12.5 (enriched), and the BSFC coefficient will depend on what kind of engine you have, atmospheric or turbocharged (atmosphere - 0.4-0.52, for turbo - 0.6-0.75).

Having learned all the necessary data, enter the indicators into the corresponding cells of the calculator and by pressing the "Calculate" button you immediately get a result that will show the real engine power of your car with a slight error. Note that you do not need to know all the parameters presented, you can clear the power of the internal combustion engine using a separate method.

Functional value of this calculator is not about calculating the power of a stock car, but if your car has undergone tuning and its weight and power have undergone some changes.

Questions about the calculator,

and also leave ideas in the comments

How to calculate engine power

Engine power determines its high-speed qualities - the more powerful motor, the greater the speed the car can reach. Methods for calculating the power of an internal combustion engine and an electric motor are different. Let's consider them.

Typically, the power ratings of an internal combustion engine are indicated in the technical specifications. However, over time, the resource is depleted and the capacity weakens. To do this, you can check it with the help of specialists and certain equipment.

If you want to experiment and calculate the engine power yourself, for this you need to find out the mass of the car (from the data sheet), determine the mass of fuel in the tank and the driver. After that, quickly accelerate the car to a speed of 100 kilometers per hour. Record the time it took you to overclock in seconds.

To determine the power, you need to apply the following formula: P = 27.78² * m / (2 * t), that is, we multiply the mass of the car, fuel and driver by 27.78 squared, where the last figure is the speed of 100 kilometers per hour, translated in meters per second. The result is divided by the acceleration time in seconds, multiplied by 2. As a result, we get the power in watts. If you want to convert to kilowatts, then using the good old formula, multiply the resulting number by 1000. To get the value in horsepower, the power in kilowatts must be divided by 0.735.

If there is a need to measure the power of an electric motor, you need to connect the motor to a current source, the voltage of which you know reliably. The current strength in amperes of each of the windings should be measured with a special tester. Summarize the received data. Multiply the result by the voltage of the current source. The resulting number is the power of the electric motor.

Motor power can also be calculated by size. To do this, determine the diameter and length of the stator core in centimeters. Measure the synchronous speed of the shaft and the network to which the motor is connected.

Next, calculate the polar division constant. The diameter is multiplied by the synchronous frequency and a constant number of 3.14. Divide the result by the sum of the mains frequency and 120. Using the pole division and their number, determine the constant C for the motor. To do this, use the table. Power is calculated by the formula P = C * D² * l * n * 10 ^ -6. The resulting number will determine the power in kilowatts.

It should be noted that in real life engine power by and large depends on the speed. Therefore, for maximum speed, the power of the motor matters, and for acceleration, the torque is important.

What is the engine power?

Engine power expresses the ratio of the mechanism to the time interval of its completion. The standard unit for measuring engine power is “horsepower” (1 hp = 736 watts). The maximum power value is often reached at 5600 rpm, perfect crankshaft in a minute. It is easy to find out what engine power your car has without making calculations, since it is the value of the maximum power that is indicated when describing the parameters for the engine power of the car. Please note that the maximum power value and the maximum torque value are achieved both at different engine speeds and at different speeds.

To calculate the power value car engines there are not only various units of measurement, but also different ways measurements that show different results. The standard method of measuring power in kilowatts, which is accepted in Europe. If the power is indicated in horsepower, then in different countries the measurement methods will differ (despite the fact that the same horsepower will be calculated). Japan and the United States use their own standards for determining engine horsepower, however, they have long been unified with others.

How to find out the engine power of a car

So, in America and Japan, two types of indicators are used: net and gross.

1. Net measurement. Measurement of net engine power (from the English netto, net) means bench testing of a car engine, which is equipped with all auxiliary and necessary for operation vehicle units: fan, generator, muffler, etc.
2. Gross measurement. By measuring the gross engine power (from the English brutto, gross) is meant a bench test of an engine that is not equipped with all the additional and necessary units for the operation of a vehicle: a muffler, a cooling system pump, a generator, etc.

The gross power indicator can give a value greater than the net power data by 10-20% or more. This discrepancy was exploited successfully by North American car manufacturers by overstating engine horsepower ratings until a new federal standard was set in 1972.

Calculation of engine power

For gross and net indicators, one value of "effective power" is characteristic: Рeff is an indicator of the measured installed engine power.

Engine power: Ppriv = Peff × K, where Ppriv is the power converted to a certain reference state (reduced),

K is the correction factor.

The concept of "horsepower of a car" was introduced in the 18th century by James Watt. It is a parameter that measures the power of a car compared to the power of a horse.

1 horsepower or hp is equal to the power required to lift a 75-kilogram load to a height of one meter in 1 second. In some cases, it is customary to translate hp. in kilowatts - then 1 horsepower will be equal to 735.5 W or 0.735 kW.

To determine the power in hp. of a specific car, it is necessary to convert the kW indicated in the passport data into horsepower. It is done like this: the given values ​​in kilowatts are simply divided by 0.735. The final value will mean the horsepower of a particular car.

Several examples for comparison.

1. Nissan Micra with a 1 liter engine has a power indicator of 48 kW. To determine the parameter in horsepower, you must divide 48 / 0.735. It turns out 65.3 or roughly 65 horses.
2. Sports version of the famous Volkswagen Golf with TSI motor 2.0 l has a power of 155 kW. Dividing the number by 0.735 gives the value in hp. - 210.
3. The passport data of the domestic "Niva" indicates 58 kW, which is equal to 79 hp. This value is often rounded up to 80 hp.

There is another way to calculate horses. Almost any large service station has a special setting that easily determines how much horsepower is in the car. The car is lifted onto the platform, fixed, the accelerator pedal is squeezed out to the stop. The computer will calculate the value in a few minutes.

It is customary to distinguish between 2 measurement systems: domestic and European. Both equate hp. up to 75 kg x m / s.

So the horsepower in the car is equal to the kW divided by 0.735. Kilowatt is the metric unit of horsepower. Scientifically, it is comparable to the work performed in 1 second when lifting a load weighing 75 kg to a height of one meter. All this taking into account gravity.

A modern car is considered highly efficient if its engine has more power in relation to the mass of the vehicle. Or like this: the lighter the body, the more the power parameter will allow the car to accelerate.

This is clearly seen below on the example of high-performance cars.

• Dodge Viper with a capacity of 450 hp has a total mass of 3.3 tons. The power / weight ratio is 0.316, acceleration to hundreds - 4.1 s.
• Ferrari 355 F1 375 hp - full mass 2.9 t, ratio - 0.126, acceleration to hundreds - 4.6 s.
• Shelby Series 1 320 hp - gross weight 2.6 t, ratio - 0.121, acceleration to hundreds - 4.4 s.

Some automotive publications write that the price of a car is determined only by the "horses" under the hood. Is it so? And why do they prescribe torque or KM in the technical data of the car?

CM is a consequence of influencing the lever, familiar to everyone from physics lessons. Accordingly, the measurement term in Nm is also displayed. In the internal combustion engine, the role of the lever is played by the crankshaft, and force or energy is generated by the combustion of fuel. It acts on the piston that creates the CM.

It turns out that the magnitude of KM is also important, as well as power. Only the last parameter implies already another work performed per unit of time. It shows how many times the internal combustion engine creates CM in a unit of time. Power is determined by the amplitude of rotation of the power plant or revolutions, which means it depends on the CM. That is why it is calculated in kilowatts.

Now directly about the influence.

1. The power of the car is required to force certain resistances. The higher it is, the bigger car able to outlast. In this case, the opposing forces are the forces of friction and wheel rolling, the resistance of the oncoming air, etc.
2. KM affects the capabilities of the car directly, because next to the "horses" parameter, revolutions are always written, on which the optimal power depends.

Thus, the vaunted horsepower of a car is nothing without torque, because it is the latter indicator that determines the dynamics of acceleration, affects the achievement of the peak of power by the engine.

Horsepower also directly affects the transport tax, which is determined by the law of the country. The higher it is, the more you will have to pay for the car.

You can also calculate the tax on a car or fuel pump on your own, using the following formula: hp. car x current rate and the component inferred by the tenure ratio vehicle to the total number of months in a year.

Example 1.

Lada Vesta is equipped with an engine that develops 105 hp. If the owner lives in Moscow, then the tax rate for today is 12 rubles. From this it turns out that the cost of the heat pump for 1 year will be equal to:

• 12 × 105 = 1260 rubles.

Example 2.

Volkswagen Golf, equipped with a 2.0 TSI GTI engine with 152 kW KM, has a power of 207 hp. We calculate the tax:

• 12 × 207 = 2484 rubles.

Example 3.

The top car Ferrari GTB coupe has 270 horses under the hood. Accordingly, the tax will be:

• 12 × 270 = 3240 rubles.