Meters, elastic horses and Newtons with engines. When buying a car, almost everyone pays attention to the number of "horses" in it, some, however, look more at the color and the presence of mirrors in the sun visor.
Any motorist will tell you that the average value of "horses" for a budget sedan these days is in the region of 100-120. But what torque is, why it is needed and how Newton affects horses - not many people know.
Today we will try to understand all this.
How often, when pressing on the gas, did you notice that the car "does not move", although under the hood there seemed to be a "herd of 150 heads of purebred Japanese (German / Korean or other) horses? I had to observe how lazily the tachometer needle starts moving from 2000 , and reaching the mark of 3000-3200, wings appear in the car and the acceleration dynamics increases sharply?
Usually, manufacturers indicate the maximum power of their cars. Maximum - because it is not always available. Normal city driving uses only a fraction of the vehicle's horsepower. Maximum "horses" are achieved at sufficiently high speeds. For four cylinders of "civilian" cars, this figure is in the range of 5-6 thousand revolutions, however, power affects the maximum speed more, but the acceleration dynamics depends on the torque and on the elasticity of the engine.

Torque is the product of the force on the arm of the lever to which it is applied, Mcr \u003d F x L. The force is measured in newtons, the lever is in meters. 1 Nm is the torque that creates a force of 1 N applied to the end of a lever 1 m long. In an internal combustion engine, the crankshaft crank plays the role of a lever. The force generated during the combustion of fuel acts on the piston, through which it creates torque. What is important for a motorist is that torque is a quantity that determines how quickly an engine can gain maximum power, which means it will achieve maximum acceleration dynamics. As well as power, maximum torque is indicated for specific engine speeds. In this case, an important parameter is not so much the magnitude of the moment as the speed at which it is achieved. For example, for a sharp acceleration during a quiet ride (2500-3000 rpm), the engine whose torque is reached at low speeds is more preferable - you press the pedal and the car fires.

The figure shows the dynamics of a BMW 318i.

The graph shows that the power is constantly growing, up to 6500 rpm, however, the maximum torque is in the range of 3400-4000 rpm, which seems not entirely logical, because the engine speed is still growing.
However, if you take a closer look, then there are no contradictions in this schedule. The fact is that the torque in the cylinder does continue to grow, however, the torque measurements are measured at the exit of the engine, and the standard four-stroke civil car engine most often has four cylinders. It turns out that part of the torque of the first cylinder is spent on the exhaust stroke of the second cylinder, and the third cylinder needs to go through the compression stroke of the fuel mixture, which is quite difficult to do with an increase in the speed of the cylinders, and in the fourth - the intake stroke, which also consumes energy.
So, we see that at high speeds we will have enough power to reach maximum speed, however, this will take a long time. To reduce acceleration time and make it smooth and comfortable, you need to take into account the elasticity of the engine, that is, the segment of the torque graph where the indicators are closest to the maximum. In our case, this is 3400-3800 rpm. Thus, having reached the mark of 4000-4200, you should switch to an increased one, then the speed will drop to 3000-3200 rpm, which, when you press the gas, will quickly bring the engine into the zone of maximum torque. The same circuit works in reverse when reducing the speed and switching "down".

Horsepower (hp) is a non-systemic unit of power. Currently, it is officially out of use in Russia (the standard SI unit for expressing power is watt), but still continues to be widely used in the automotive industry as an indicator of engine power.

In 1789, Scottish engineer and inventor James Watt coined the term "horsepower" to describe how many horses his steam engines could replace.

You should know that horsepower is not the maximum, but the average indicator of the power of the horse, which it can maintain for a long time. In the short term, an average horse can develop a power of about 1000 kg * m / s, that is, the power of one horse is 13.3 horsepower.

The main units of measurement of engine power and their designation

1. Horsepower(735.49875 W). Denoted as: hp (this is the net engine power, measured using engine accessories such as: muffler, alternator), bhp (this is the gross engine power, measured without using additional units).

You can also find other designations: PS (German), CV (Fr.), pk (nid.).

In English-speaking countries, it is still more common to equate horsepower to 745.6999 watts, which is approximately equal to 1.014 European horsepower.

2. Watt

Since the description of the watt is beyond the scope of this article, we will not touch on it here.

Horsepower is a conditional and ambiguous unit of power.

In Russia and in almost all European countries, horsepower is defined as 75 kg * m / s (metric horsepower), that is, as the power sufficient to lift a load of 75 kg to a height of 1 meter in 1 second. In this case, 1 l. with. is exactly 735.49875 watts.

The maximum power that a horse can develop is called boiler horsepower. You can easily calculate your maximum power. To do this, you need to measure the time t during which you run up the stairs with height h and substitute it into the formula: m * h / t, where m is the mass of your body.

To determine the engine power, special stands are used, more about this is written below.

Engine power is measured mainly to evaluate the effectiveness of tuning.

To determine the power of the engine, there is only one exact way: remove it from the car and install it on a special stand. Removing and installing an engine is a rather laborious and expensive process that only automakers and serious racing teams can afford.

For a less accurate measurement of power, power dynamometers are used (such as in the photo), which allow you to take readings “from the wheels”. The result can be influenced by: tire pressure, their grip properties, tire temperature (during the measurement, the tread gets very hot) and even the degree of tightening the car with safety slings.

Measurement technique

A warm car starts off in first gear, accelerates to 40-50 km / h, after which the last gear is engaged, the gas pedal is pressed all the way and simulation of acceleration begins. Upon reaching the maximum speed (since the beginning of the power drop visible on the monitor), the neutral gear is engaged.

The result of the measurement is displayed in the form of a graph that shows the dependence of power on engine speed (blue curve - in horsepower).

To get an idea of ​​the power range of the motors, please refer to the following figure:

• 0-100 l. with. - small cars;
• 100-200 l. with. - vehicles with a medium power engine;
• 200-500 l. with. - sports cars;
• 500 l. with. and more - racing cars and supercars.

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Power in a car is one of the main criteria. Today you can find cars with different power ratings, but what solutions to choose for the most quality ride? Sometimes the company offers engines so extensive that the same model offers power units from 100 to 250 horsepower. So, for example, happens in the British corporation Mini. But experts and experienced drivers call it nonsense and a bad idea. Since each car has a fairly large number of advantages in a particular design. The entire suspension, body, interior elements - everything is calculated for a specific power, dynamics and speed. And also the weight of the engine and other parameters are important. Therefore, with a large spread, it is difficult to make a good car for each unit at the same time, taking into account all the characteristics.

However, the Mercedes corporation has precedents, how the same car can be the best offer with a 120 and 350 horsepower engine. The AMG series has been slightly redesigned in everything - suspension, interior, controls. Therefore, the most powerful cars often fully justify themselves. However, only a few representatives of transport behave in this way. In most situations, there is a specific problem that needs to be solved. And the car solves a specific problem. Therefore, it is often completely useless to put an engine with three hundred horses in an ordinary city car. This simply increases fuel consumption and does not bring anything good to the buyer. So it is worth paying more attention to the choice of engine and its technical characteristics.

Small class of urban hatchbacks - what is the "golden mean"?

For a small class, the optimal set of horsepower is considered to be power from 80 to 110 horses. Anything above this figure is redundant. Anything below is annoying and annoying when traveling. Therefore, the same Matiz with its 52 horses simply does not get good reviews due to its low power. The optimal qualities for the machine are as follows:

• acceleration to 100 km / h in no more than 11-12 seconds, otherwise the dynamics will be too small to get a more or less high-quality trip through city streets;
• a convenient gearbox with short shifts, which will not make the driver work on shifting and get tired of this business, everything should be clear;
• when overtaking, there should be no problems that can lead to accidents and other unpleasant consequences, there should always be a certain power reserve;
• fuel consumption is a central issue for many car buyers today, this is a really important indicator, it should not exceed 7 liters per 100 km in the city.

Such parameters of a small city car open up a fairly large choice for us. There are European, Korean, Chinese cars that are worthy of your attention. But you should pay some attention to the build quality, decent performance of the interior. Each buyer will have their own set of criteria that should be considered.

C-class cars - mass segment in Russia

Equalization in this class has always been on the VW Golf, so it is often perceived as the only correct option for comparison. Today the Golf comes stock with a 110 horsepower engine, and that's very little. There is a second unit - 1.4 TSI for 122 horses, and it turns out to be optimal for this car. The tasks of the machine are:

• provide not just decent dynamics, but a fairly active ride, if we are talking about a car with a sporty appearance and other important advantages;
• gearboxes must perform clear and fast shifts, while saving fuel, the German 7DSG robotic gearbox on the Golf is excellent;
• with less power, the car remains defenseless on the road, and if the driver does not feel this immediately after buying a car, then after a month of operation it catches up;
• Fuel consumption is important, but not critical for a C-class car buyer, it is important to keep a balance between spending money and getting a quality ride.

The Japanese flagship in this segment, the Toyota Corolla, comes with a 99 horsepower base engine, but it's not just small, it's tiny for this car. But the units for 122 and 140 horses just perfectly perform their functions. Interestingly, small units do not save fuel, consumption is almost the same as on adult engines.

Elite sedans - do volume and power parameters matter?

In expensive luxury sedans, the fuel consumption parameter does not matter. Also do not take into account the numbers indicating the volume of the power unit and the amount of horsepower. Buy a car for comfort, speed and acceleration, dynamics and handling. However, the engine plays a role in the choice of transport and performs the following functions:

• acceleration - the more powerful the unit, the greater the acceleration on any section of the road, this is important for a dynamic and comfortable trip in any situation;
• dynamics - sometimes you have to rush a lot, so fast overtaking on the track becomes an important means of saving time, so volume is important;
• reliability - the car should not be allowed to break down on the road or fail while traveling to certain meetings and other important events in the life of a businessman;
• the style and quality of all the details are sometimes more important than all the characteristics of the engine, so often choose a car only for design parameters.

So engine size is sometimes not the most important factor in such a car. The number of horses in luxury sedans ranges from 120 to 500. Here it is important to understand the meaning of buying a car. You can give preference to the Passat with 122 horses or buy a Bentley with a 625 horsepower engine. The choice will always carry certain consequences.

Crossovers - choose the best power indicator

For comparison, we will take mid-size crossovers such as the Toyota RAV4. This representative of the class has a base engine that develops 146 horsepower, and there are also units for 150 and 180 horses. These are the optimal indicators that all class leaders support. Therefore, in the range from 140 to 200, you need to choose a power unit. Such an engine will be able to perform the following tasks:

• optimal movement on any road with a sufficiently high quality of operation, the absence of overloads and the resulting problems with the car;
• good acceleration, decent dynamics on the track for safe overtaking, excellent response to all traffic events and the presence of a power reserve;
• confidence in movement, which creates certain advantages for each buyer, provides important benefits for operating a car in any conditions;
• reliability and durability - it is in this power range that the units can run the most time and get the most pleasant opportunities.

For a crossover, the 105 horsepower engine, as is often the case in Chinese solutions, is too weak. He will not be able to lift the car up a steep mountain and will not normally overtake passing vehicles. This closes the freedom of movement and makes buying a crossover a completely uninteresting idea. So it is better to give preference to more powerful motors.

Luxury SUVs - measuring ideal power

Again it is worth looking at the market leaders. Toyota LC 200 engines start at 249 horsepower and end at 400 horsepower. The Nissan Patrol has only one 405 horsepower engine. The largest SUV Mercedes G-Class offers engines of 245 and 422 horsepower. The main tasks of the units are:

• carries a car buyer along simple roads so that there is no feeling of bulkiness and sluggishness of a large car, overtaking a car without any problems;
• provide a sufficiently high freedom on the road, freedom of decision-making on overtaking, speed and acceleration, give normal confidence when traveling;
• be a reliable and durable solution for every motorist, regardless of certain styles of transport and other features of the trip;
• fuel consumption, although not the most important, still in a certain way affects the choice of a car with a specific engine when buying in the cabin.

Almost all class leaders provide such conditions even with basic power units. In this segment, it is very difficult to single out a car that would become the undisputed leader and could offer much more benefits than all rivals. The reference elite car is difficult to choose due to the fact that each buyer will protect exactly his choice. We offer a short overview of one of the representatives of elite SUVs:

Summing up

As you can see, power is really important for a motorist. Often we buy a car, paying attention only to the basic parameters of transport, but there is much more to consider. In particular, it makes sense to look for transport options that are fully suited to your travel style. Engine power and displacement is one of the important indicators that you should always look for sufficient performance when buying a car. If you do not take into account the important parameters of the power unit, you will not be able to get a decent car with good performance.

However, for each buyer there are certain criteria for purchasing a car, so there will always be someone who will criticize a good choice. It should be understood that driving and operating vehicles are purely individual things. Therefore, you should not let smart experts and experienced transport owners lead you astray. You buy a car according to your requirements and will not forgive yourself if you buy the weakest engine and will experience problems with its operation in the future. Do you choose the most powerful or the most economical unit option when buying a car?

To calculate the power of the engine, a parameter called horsepower is used. Every person close to automotive topics knows that this parameter must be indicated in the documents for a vehicle. However, power is not always determined by horsepower. So, motor power can be measured in kilowatts per hour. To get accurate calculations, you need to know a few things.

You will need the following:

• vehicle;
• TO station.

For a clear understanding of the process of measuring the power of a car engine, below is a sequential algorithm of steps that allows you to quickly understand the process of interest.

Procedure:

Interesting to know! In 1789, in Scotland, James Watt was the first to use the concept of "horsepower" to determine the power of a car engine.

So, using the knowledge gained in high school in mathematics lessons, as well as spending a little time, you can determine an important parameter of your vehicle - engine power.

The term "horsepower" was coined by engineer James Watt. Watt lived from 1736 to 1819 and is one of the best known and most honored scientists for his work on improving the efficiency of steam engines. We also say his last name almost every day when we talk about 60-watt light bulbs.

The story goes that Watt worked in a coal mine where coal was lifted from the mine by a pony. Watt wanted to find a way to affirm and talk about the power generated by this animal. He found that the average pony could do 22,000 foot-pounds of work in one minute. He then increased that number by 50 percent and tied the measurement of one horsepower to 33,000 foot-pounds of work in one minute. This arbitrary unit of measurement has made its way through the centuries and now measures the performance of your car, lawn mower, chainsaw and even in some cases your vacuum cleaner.

Simply put, horsepower is measured as follows: according to Watt's measurements, one horse can do 33,000 foot-pounds of work every minute. So imagine a horse lifting coal from a coal mine, as shown in the picture. A one horsepower horse can lift 330 pounds (~150 kg) of coal to a height of 100 feet (30.5 meters) every minute, or 33 pounds (15 kg) of coal 1000 feet (305 meters) per minute - you can make any combination of weight to height for a time that you like. As long as 33,000 foot-pounds per minute is being done, you have exactly one horsepower.

You might also try a combination such as loading 33,000 pounds (15 tons) of coal into a huge container and asking a horse to lift it 1 foot (30 centimeters) per minute, but find that the horse physically cannot move with that weight. You can probably also imagine that you put 1 pound (450 grams) of coal in a bucket and ask a horse to lift it 33,000 feet (about 838 meters) per minute, thus reaching a speed of 1183 km / h, and the horse , of course, will not be able to develop such a speed. However, if you have read Archimedes, and simply if you are over 10-12 years old, then you know what a lever is and that you can easily change the ratio of mass and speed using a lever. In this way, it is possible to create a block and solve a system that does not put a comfortable amount of weight on the knight or does not allow him (the knight) to move at a comfortable speed, no matter how much weight you actually need to move.

Now you and I know what James Watt meant by horsepower. However, today power is measured in a slightly different way and can be converted to other units. Moreover, in Russia, the term "horsepower" is officially used only when calculating the transport tax, while in other areas, Watts are considered to be the official unit of measurement. Today, there is also a metric measurement of horsepower - without going into details, it is about 735.5 watts, or 75 kgf m / s (the work that is done when lifting a load of 75 kg to a height of 1 meter in 1 second, and that's all this is taking into account the terrestrial value of the acceleration of free fall).

And now a little about the practice of using the term "horsepower" and the overall performance of the car.

A car is considered "highly efficient" if it has more power under the hood in relation to the total weight of the car. This makes sense, because the less weight you have, the more power you have to speed up the car. For a given amount of energy, you want to minimize weight in order to maximize acceleration.

The following table lists the horsepower to weight ratios of several of the most famous performance vehicles. You already understand that the higher the ratio of power to weight, the better, and you will see that this is not always directly proportional to the price of the car.

	Power (hp)	Full mass(kg)	Power/weight ratio	Acceleration 0-100 km/h(sec)	Price
Dodge Viper	450	3 320	0.136	4.1	$66 000
Ferrari 355 F1	375	2 975	0.126	4.6	$134 000
Shelby Series 1	320	2 650	0.121	4.4	$108 000
Lotus Esprit V8	350	3 045	0.115	4.4	$83 000
Chevrolet Corvette	345	3 245	0.106	4.8	$42 000
Porsche Carrera	300	2 900	0.103	5.0	$70,000
Mitsubishi 3000 GT	320	3 740	0.086	5.8	$45,000
Ford Escort	110	2 470	0.045	10.9	$12 000
Lada Kalina (Norm 1.6)	81	1 555	0.052	13.3	RUB 335,000
UAZ Patriot (Welcome 2.7)	128	2 650	0.048	19	580 000 rubles

You can see a very definite correlation between power to weight ratio and acceleration time in most cases, a higher ratio indicates a faster car. Interestingly, there is much less correlation between speed and price. This is explained by a huge number of factors, ranging from the brand of the car to the configuration of a specific specification.

If you want a fast car, you need a good power-to-weight ratio.