What Is Horsepower in Cars and How Does It Relate to Horses?

October 22nd, 2020 by


Every car or truck you buy has a horsepower rating for its engine. The 2019 Chevy Malibu, for instance, has 160hp or horsepower.

What is horsepower in cars? Horsepower is a measurement of the power generated by the engine. There are a few standards used when determining horsepower.

The term horsepower did not start with combustion engines. James Watt, the engineer who the term “watt,” is named after, created it. He first used this term in the late 1700s to describe the amount of power put out by steam engines.


What Is Horsepower in Cars?

The original measure of horsepower started off calculated differently than we use now. In fact, up until 1971, the term “gross” horsepower was most common. Now, people calculate horsepower by multiplying torque by maximum speed and dividing by 5252.

Horsepower is a basic measurement of how much power and energy the engine will generate. There are a lot of misconceptions about horsepower and how it plays into the understanding of engine output. There are a few myths about horsepower in cars, and what it means.


Horsepower Has Little to Do With Horses

In the late 1700s, the term was used to describe steam engine performance vs draft horses. If this sounds like less than an exact measurement, you are correct. An actual horse can put out, on average, a little more than 14 horsepower at maximum.

You may be surprised to learn that a human can generate several horsepower as well. It’s not a measurement of the work that can be done by one horse. This is a persistent myth that many people still believe to this day.

In this way, the term can be considered misleading. It is so common, however, that while the calculation has changed, the terminology remains the same. Before 1972 the term gross horsepower was measured on engines that weren’t connected to exhaust or air intakes and were operated on stands.

This is why after 1972, most engines lost upwards of 100hp off their engine rating. The actual horsepower they were generating was different than the measurements used up to that point. This is also why modern vehicles are often referred by other measures, such as by litre ratings.


What Is 1 Horsepower?

If you are wondering what horsepower in cars is, it is 550 ft/lbs per second of energy per horsepower. This is how it is measured using equipment designed to test the crankshaft. This is also why a horsepower rating doesn’t stay the same between calculation and testing.

If you purchase a vehicle with 200 horsepower and then put that same vehicle on a machine, it will test lower than 200. This is because horsepower is measured as peak energy output. So unless you are receiving a perfect operation from your vehicle, the actual horsepower of the motor is less than you think.


Horsepower Can Be Reduced

Just because a vehicle generates a certain amount of horsepower in one instance doesn’t mean it will always produce the same amount. The most common culprit of this is a reduction of airflow into the engine, but restricting exhaust will also reduce horsepower.

This is why keeping an engine in excellent condition with all filters clear and changed regularly is essential. By maintaining a consistent amount of airflow and proper exhaust, you preserve the function of your engine near peak levels. Servicing your car’s engine is of the utmost importance if you want performance.

The fuel system of the vehicle also impacts the horsepower generated by the motor. To have peak horsepower performance, you must have an adequate flow of fuel to the engine. Fuel pumps and fuel filters are central to the function of your vehicle in this regard.

Other environmental factors affect the horsepower of your vehicle. Many of these you can’t change, but as long as you keep your car serviced, it should perform to your expectations. Service and maintenance are also crucial for the longevity of your engine.

It is for these reasons that the horsepower of an engine can fall as the engine ages. The build-up of carbon and other pollutants in the engine will begin to restrict its operation.


What Does Horsepower Mean?

What horsepower means is the amount of work your engine can perform. Speed and torque are part of the calculation of finding horsepower, but not indicative of horsepower alone. You must have both torque and speed to have a high horsepower.

This means that some engines that are put in cars are capable of being very fast, but don’t have a high horsepower total. If you’re purchasing a vehicle that only has 200 horsepower, that doesn’t mean it will be slow.

This is another common misconception about vehicles. The myth that horsepower equals speed is often due to the high horsepower ratings of older vehicles from the 1960s. This was known as the golden era of muscle cars, and many people associate fast vehicles with cars of this time.

Your modern vehicle that has a much lower horsepower rating will be as fast or faster than many of the supposed fast cars of the past. This is because more power is generated by the engine per the weight of the vehicle. The lighter the car, the faster it can be propelled with less energy used.


Horsepower in Your Decision

There are more important concerns than horsepower. What is horsepower in cars can be a misleading question and answer. To a certain extent, horsepower is an important measurement, as it does form an aggregate of power and speed. Just remember, this is not the entire story.

The best way to get a good vehicle is to go to a trusted dealership. If you have any questions about vehicles or want to know more about what is available, contact Viking Motors. We can get you the answers and information you need, and make sure you get the vehicle you want.

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