What is horsepower, torque?

horse power

Horse power

Since we are all talking about engine power, here is a text that aims to shed some light on what each of these quantities means in real life. To describe the effort that horses have made since ancient times by doing not very pleasant jobs, scientists have tried to describe the work (which the horse performed), the time (which the horse spent working) and the interdependence of these values. The result is what we all now call "Horsepower."

DEFINITION OF HORSE POWER

According to this story, we have a definition, which we stick to today, which says that one KS = 75 kg m / s. Let's turn it into an understandable dictionary: the average horse (powerful 1 hp) is able to lift an object weighing 75 kg in 60 m by towing it for 1 minute (Figure 1). More recently, by switching to the metric system, we are expressing power in watts (W) or. kilowatts (kW). What further poses the problem is the conversion of these values.

The ratio is as follows: 1 HP = 0,735 kW ie 1 kW = 1,35962 HP.

DEFINITION OF TORQUE

However, describing power is not enough to fully grasp the performance of the engine you need another size: Moment of force.

Commonly known as "torque", Is in fact something that is" equal to the product of the force and the distance of the place where that force acts from the axis of rotation. " But what is it really about? Imagine a wrench to remove the screws on the wheels. The longer the lever you have, the easier the unscrewing job will be because you will apply the same force at a greater distance from the axis of rotation (screw). This distance is called the "arm arm", and what you apply to the screw when unscrewing is called the "torque" (unit: Nm).

Silas

Flowchart of 4-cylinder otto-engine:
- maximum power 33 kW (45 hp) at 5000 rpm
- maximum torque 88 Nm at 2800 rpm
It is necessary to mention another detail, and that is the engine speed. The higher the engine speed, the clearer - the higher the amount of fuel burned, and thus more energy is produced. Simplified, more revolutions - more power if we look at it through one and the same period of time.

And finally, for the first time, we get the opportunity to increase power and momentum, which will be done by the magic formula: KS = Nm * O / 7024, where O is the engine speed expressed in 1 / min.

power

Why is all this important to us?

Engine power is important to know if a car will go fast. We need a moment to know when that car will go fast. Simply put, the higher the maximum torque that an engine develops (at a certain speed), the better the car will "pull" at lower speeds, because at the same time its engine will be able to achieve more power at lower speeds. The torque and power curve with respect to the engine speed (Figure 2) very vividly describes the interdependence of these three elements.

Since we constantly mention some horsepower, it is fair to say that this is a metric unit of power defined according to the standard DIN (Deutsches Institut für Normung) 66036. This unit was abandoned in 1972, since when the unit kW (or basic unit W) has been used. ) according to the international system of units also known as the SI system (abbreviated from fr. Le Système international d'unités)

Of course, the term horsepower is still widely used in the literature (but also for promotional or marketing purposes), including several derivatives. Namely, while it would be simplest for all of us in the world to speak (and write) in kilowatts, this is certainly not the case.

So in Europe it is about DIN horsepower (German: PS - Pferdestärke), but the British and Americans use "their" horsepower which they call horsepower (HP) or Brake Horsepower (BHP). In the latter case, it is an expression created on the basis of the method of measuring engine power using the De Prony brake, the forerunner of today's dynamometer. Horsepower, or HP is a unit that belongs to the SAE (Society of Automotive Engineers, now) standard SAE International) and is converted to a factor of 746 in watts. 1 HP = 0,746 kW, or. 746 W. The Japanese, however, will refer to JIS (Japanese Industrial Standard) D 1001.

And, having already concluded all of the above so nicely, it is our turn to offer you a few more formulas for the end of today's story:

1 HP (DIN) = 0,98632 HP or BHP (SAE) => 1 HP or BHP = 1,01387 HP

1 Nm (DIN) = 0,737562 lb-ft (pound x rate, SAE) => 1 lb-ft = 1,355818 Nm

If you are experiencing torque expressed in kilograms (kgm), do not despair because 1 Nm = 0,101972 kgm. Of course, the point becomes clearer if we look at the familiar figure: 9,81. Of course, this is the ratio of weight (N) and weight (kg), so conclude the rest of the sentence yourself…

Sources:
nacionalnaklasa.com
www.autonet.hr


One Comment

  • Ugh says:

    Please explain to me how at one point the torque starts to drop while the speed continues to increase? Shouldn't the torque increase as long as the rpm increases .. because the formula for ob is Nm = F * r * sin (angles) .. r is the distance from the axis to the beginning of force F. The force F is m * a .. (a) is acceleration, which in this case gives it an increase in speed. right? if so, do I fuck it down then torque with increasing rpm. I think I know that a = 9.81m / s2 but you understand what I'm asking you ..
    thanks in advance. greeting

Leave a reply