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Why do we say Horsepower

Without thinking the enthusiastic motorist will discuss their vehicles in terms of the horsepower that its engine can produce. Of course, when you look into the engine compartment there is not a horse to be seen anywhere! So why do we use the term horsepower in relation to our automobiles?

As the term suggests there is a historical connection between horsepower and the power produced by an engine, which is purely now one of calculation. However, despite the fact that many would say that the term “horsepower” was coined by the Scottish engineer James Watt, when trying to interest investors in steam power, as a measurement of power there are recorded incidents of its use around eighty years earlier.

In 1702 Thomas Savery, a miner, when considering the value of changing from the use of horses to engines stated that, for this to be a viable option, it was necessary for that engine to be developed to such an extent that it could complete the same amount of work as X number of horses. Should this not be able to be achieved he argued that the engine would add no value to the mining process.

Over the following eight decades there were many studies made into the power of the horse and the way this might be measured and equated. Engineers John Smeaton and John Desaguliers originally calculated that a horse was able to produce up to 27,500 foot pounds per minute. However, it was James Watts’s calculations that finally caused the term horsepower to transition from the animal to the mechanical engine.

Originally Watt studied pit ponies and found that they could produce 22,000 foot pounds per minute. However, as this was significantly less than the previous experiments it was not a notable achievement in engineering circles. Undaunted. Watt decided to conduct the same exercise with horses rather than ponies. It was the result of this experiment that caught the interest of investors. Watt had discovered that horses could produce more percent more power than ponies. In other words he had determined that a horse could lift 33,000 pounds at the rate of one foot per minute.

Watt used this discovery and measurement in his discussions of the benefits of steam power over the horse and it caught the attention of the engineers of the day. Suddenly they had an equation on which to base the output of their engines and one that could be measured directly against a physical experiment.

Thus it was as a result of Watt’s persistence that the term “horsepower” became an industry standard measurement for the automotive engine manufacturers. Therefore, if your vehicle produces 200 horsepower just consider the size of the horse herd that would be required to produce the same level of power!

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