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Q: What is Horsepower?

December 17, 2013 12:53 PM

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The amount of work being done over time can be measured in units called horsepower, or hp. The term was first used by Scottish inventor James Watt in comparing the work potential of steam engines to that of teams of horses. It has remained a popular unit of measurement for the automotive industry and is widely used today to describe the amount of potential power one engine offers over another. When compared to electric units, one horsepower equals approximately 746 watts.

Larger engines tend to create more horsepower and torque (the other significant measure of engine power). This doesn't always result in faster cars, however. Often this power is needed to haul tremendous amounts of weight. A pickup truck needs more power than a subcompact for this reason.

Many modern engines are shaped like the letter "V." The arms of the engine are made up of cylinders containing pistons. These pistons work to turn the base of the engine, or the crankshaft. A V8 has eight pistons turning the crankshaft. This, in turn, provides a greater ability to create more power than an engine with only four or six cylinders. This is the reason larger vehicles have larger engines. A pickup truck is often fitted with a V8 to keep up with practical weight and speed demands.

Car manufacturers regularly produce a model with two or more engine choices. Opting for the smaller engine will often help you save significant cash, but many consumers assume more is better. It's important to know how much power you need before making an expensive decision. Thankfully, there are ways to see how well both engines perform without spending an unreasonable amount of time test driving different models.

There are three basic areas to look at when evaluating which engine you need. The first is acceleration. How quickly does each model go from 0 to 60 mph? Consider your route to work and normal weekly activities to determine whether you need anything quicker than the base model. After that, look at towing capacity. Do you lug around a professional tool box or welding unit, or is your biggest load during the year going to be a load of luggage? Finally, consider what you'll need to haul. Will you be towing a travel trailer or camper? Do you realistically see yourself using a towing package? If not, you probably don't need the bigger engine offering more horsepower and torque. Knowing this could save you thousands of dollars on your next auto purchase.

While consumers no longer use horsepower to compare machines to workhorses, the unit of measurement can be helpful in comparing one engine to another. Vehicles use power for a variety of reasons, and owners may need the extra push to handle speed, hauling, or towing needs. Understanding which features are affected by horsepower helps you make the best buying decisions.

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