What is horsepower in a car

We all have heard about the term ‘horsepower’, and the relation between horsepower and speed when it comes to our cars and trucks.  The more horsepower an engine has, the faster it can make your car or truck.

Every year, cars and trucks are manufactured by the large automakers with more horsepower than the previous year’s models did.  With the advances in automotive engineering and technology, the new cars made every year have more horsepower, but most of the time, they are also more fuel efficient.

So what is horsepower in a car?

In this article, we will discuss many topics relating to horsepower, including the origin of the term ‘horsepower’.

 

Why is it called Horsepower ?

But what specifically is ‘horsepower’?  Does it actually have anything to do with horses? Well……kind of.

The term horsepower was invented by engineer James Watt, according to Wikipedia .

Does that last name sound familiar?  It should!  Have you ever changed a light bulb in your home?  If so, was it a 60 Watt bulb, or a 40 Watt bulb?  Well, the term ‘Watt’ when referring to light bulbs refers to the amount of energy that the light bulb consumes during an hour of use (when the light is on).

James Watt lived was born in 1736 and was most famous for his works with steam engines – more specifically, improving their performance.

Watt often worked with ponies in the coal mine – using them to lift heavy loads of coal.  He was trying to figure out a way to explain the power available from them as it pertained to the work of lifting the heavy coal loads.

He figured out that the ponies could do 22,000 foot-pounds (ft-lbs) of work in one minute.  He then increased that amount by an arbitrary 50% and came up with the number 33,000 foot-pounds (in one minute), and THIS is the number that has been used to describe one unit of horsepower for centuries.

Watt believed that one horse could do 33,000 ft-lbs of work each minute.  Basically, a horse exerting one horsepower worth of work, could lift 330 pounds of coal a total of 100 feet, in just one minute.  The same horse, exerting one horsepower of work, could also lift 1,000 pounds of coal a total of 33 feet, in one minute.

See the below image to get a better idea of how this was applicable to Watt’s theory.

1 horsepower

 

This idea became generally accepted as one of the most common ways to rate the level of power output of mechanical motors around the world.  These days, car and truck motors (gasoline and diesel powered ones) are rated for power in two different units of measurements – Horsepower and Torque.

In this article we will be talking about horsepower in relation to the amount of power that a car’s engine outputs.  I will explain more about what Torque is, and how it is used to rate the power of a motor in another article.

 

What does Horsepower do ?

Technically, horsepower doesn’t ‘do’ anything as it is just a term that is commonly used to describe how much power a car or truck engine has.

The components inside the engine work hard to provide cars and trucks with the necessary power to move around at various speeds.

When originally manufactured, an automobile engine is rated to have a specific amount of horsepower, and this horsepower rating is the peak horsepower at a specific engine RPM.  For engine power analysis, the unit of measure for the engine ‘revs’ is called RPMs (revolutions per minute).

The RPM of a motor is measure of how fast the engine is working at any particular point in time.  More specifically, in an automobile engine the RPM measures how many times the crankshaft rotates in one minute.  This number also represents the number of times that each piston in the engine goes up and down in the cylinder.

For a more complete explanation of what an engines RPM is, check out the article on cars.com titled ‘What does RPM mean in cars’ .

Some cars and trucks are equipped with a ‘tachometer’ that will easily show you the engine RPM level at any given moment while it is in operation.

A tachometer is a gauge that is usually found on the instrument cluster close to where the speedometer is located.  The gauge usually looks just like the speedometer, however, the numbers are significantly different.

Instead of numbers increasing by 10 mph like a speedometer, the tachometer usually has numbers listed in single digit increments.  Usually starting with 1, then 2, then 3, etc and will increase up to somewhere in the 7 through 10 range, all depending on what type of automobile it is.

The number 2, for example, indicates 2000 RPM’s (revolutions per minute).  This means that when the needle is pointing at the ‘2’ on the tachometer, the engine is currently at 2000 RPM.

This means that the crankshaft is currently rotating at a speed rate of 2000 rotations per minute.

Basically, to summarize all of the information above, it can be simply stated that:

The horsepower of a motor increases as the engine revs higher, until it reaches its peak horsepower.  After it reaches that peak horsepower number, the horsepower slightly tails off below that peak number.

horsepower vs rpm

 

If you look of the graph above, you can see the relation between RPM’s and Horsepower.

The peak horsepower occurs at a very high amount of RPM.  So, if you want to accelerate quickly in your car, you would likely downshift (in a manual transmission automobile) so that you can more easily reach the higher RPM’s and peak horsepower.

It is similar in a car with an automatic transmission – when you want the engine to provide lots of power immediately, you push the gas pedal with a lot of pressure, and the transmission automatically shifts to a lower gear to help the engine get to a high RPM level fast.

The quicker that your car can get to the higher RPM levels, the quicker that your car’s engine can provide the maximum amount of horsepower to help you accelerate very fast.

 

What is a good amount of horsepower for a car ?

The answer to this question really depends on what the expectations are of the person asking the question.

Not to get too technical, but someone who drives a smaller hatchback style of car with a small fuel-efficient engine may have quite a different answer to this question than someone who has driven full-size pickup trucks their entire life.

For instance, the #1 rated sub-compact car for the year 2018 (according to USNEWS ) comes equipped with a motor that only produces 131 peak horsepower (the LX base model).

For someone who is used to driving these types of cars, I would think that they would be quite impressed with the power of a similar sized car that had an engine rated at 225 peak horsepower.

But, for someone who is used to driving cars that have engines rated at much higher horsepower levels, stepping behind the wheel of a car with a motor rated at 225 peak horsepower wouldn’t leave quite the same impression.

If you are looking to purchase a sub-compact sized car, driving one that comes with an engine rated at 200 (or more) peak horsepower should leave you feeling quite impressed.  200 horsepower should be plenty of power to help you fly like the wind during your daily drive, being that the compact cars are not very heavy at all (relative to other cars and trucks).

If you were someone looking for a sports car, then I am guessing that you would be looking for one that comes equipped with a 300+ horsepower rated engine!

 

How much horsepower does the average car have ?

Well, again, that all depends on what type of cars you are asking about.

As an example, lets look at three very popular (in the United States) 2018 model year compact cars.  They are listed below:

 

2018 Honda Civic             158 horsepower

2018 Hyundai Elantra     158 horsepower

2018 Toyota Corolla        132 horsepower

 

Additionally, lets look at some cars that are a bit larger.  Here is three very popular mid-sized sedans that are available in the United States, and the horsepower ratings of their engines, respectively:

 

2018 Honda Accord         192 horsepower

2018 Nissan Altima          179 horsepower

2018 Toyota Camry         203 horsepower

 

Do you see a trend here?

Generally speaking, as the size of the automobile gets larger, the amount of horsepower that their motors are rated at increase.

Simply put, the more that an automobile weighs, the more powerful it’s engine needs to be to drive at the same speed as a smaller, lighter, car.

If you go check out the larger sedans you will see a significant horsepower increase, and even more-so if you were to look at the engine specifications for the mid-sized sports cars (Dodge Challenger, Ford Mustang, and Chevrolet Camaro).

However, it is important to note that the horsepower ratings of the sports cars are MUCH higher than the slightly smaller mid-size sedans.  This is due to the demand from the buyers in the market that want a fast, sleek, and sexy road machine……and the automakers know this, so the cars get faster every year!

 

How much horsepower does my car have ?

If you want to know how much horsepower your car has, you have a couple different options to help you determine this.

If your car is less than 5 years old and the engine is in relatively good condition (no large issues that would negatively affect its performance), then you can check the specifications online to see how much horsepower the engine is rated for.

I would highly recommend checking out reputable websites such as https://edmunds.com or https://consumerreports.org

Both these websites will not only give you the detailed specifications of various automobiles, but they will also provide unbiased ratings for them as well.

There is one other way to figure out how much horsepower your car has.

You can take your car into a performance shop located in your city, and have them test out the car to find out how much horsepower the engine has exactly.  This process is commonly referred to as ‘Having your car dyno’d’.

The machine itself is called an Engine Dynamometer, and this machine can determine the amount of power that your car’s engine is producing.

Check out the video above to see various suped-up cars and bikes getting dyno tested.

This is a preferred method for those who have cars that have had performance modifications done to the engine, or for those that have cars that are having issues with the engine (to help diagnose the issues).

The use of an engine dynamometer is also good for helping determine the actual horsepower of a car that has had a motor swap, or a high-mileage engine (where the engine may not be able to operate at the horsepower level it was originally rated at).

If you want to find a performance shop that offers Dyno services, I would suggest you just do a Google search using your town/city name and the term ‘dyno service’ or ‘dyno’.

 

I hope that you have enjoyed this article explaining what horsepower is and how it relates to an automobile.

In this article titled ” What is horsepower in a car ” we discusses the following topics:

  • Why is it called horsepower
  • What does horsepower do
  • What is a good amount of horsepower for a car
  • How much horsepower does the average car have, and
  • How much horsepower does my car have

If you are trying to figure out what horsepower means, and how to increase the horsepower of your automobile, then you are definitely in the right place.

Check out other posts in my blog HERE to learn more about various automobile performance upgrades and accessories.

You can also search in the various categories on my main page HERE to see all sorts of cool accessories and performance upgrades to make your car/truck the most badass on the block!!

 

 

 

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