Horsepower: The Measure of the Machine

Vroooom! Vroooom! That throaty, low roar generated by a powerful V8 or V12 engine with impressive horsepower–really gets your attention, right?

There are different standards for measuring different types of horsepower.

For example, there are the mechanical (or imperial) horsepower, approximately 746 watts, and the metric horsepower, about 735.5 watts. Eighteenth century Scottish inventor and engineer, James Watt, of the Watt steam engine fame, used the term ‘horsepower’ to compare the output of steam engines with the power draft horses (work horses) could generate. Of course, the watt, the SI unit of power–The International System of Units, the modern form of the metric system–is named after James himself. 

The British Imperial System measures one horsepower as equal to 33,000 foot-pounds of work per minute, meaning the power required to lift a total mass of 33,000 pounds one foot in one minute. How does that translate in automotive terms? Horsepower in relation to reciprocating engines is usually expressed as indicated horsepower, determined from the pressure in the cylinders. A reciprocating engine, or piston engine, is what’s commonly called a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion–just like under the hood of your car.

The challenge:

Getting the power to the ground, quickly and efficiently.

Horsepower, basically how strong your engine is, plus torque (the force that makes things rotate or turn; in this case, the force from the pistons that goes to the crankshaft that makes the axles and wheels turn) are among the critical elements in a car’s design and engineering that contribute to things like acceleration rates, stopping distances and fuel efficiency, in other words, performance and functionality.

Cars can be classified as almost anything between “mini-sub-compacts” to “muscle cars,” “supercars,” and “hypercars,” with horsepower to match in ranges from the low 100s and 300s, to 500, 800, 1,000 1,200, 1,500, and sometimes more (in pure fantasy concept cars). SAE International power and torque certification provides auto manufacturers a way to assure a customer that the engine they’re buying delivers the specs that are advertised.

 

Many top-ten lists of 2017’s best high horsepower sports cars include the Audi R8 5.2 V10 with standard 5.2L V-10 540-hp engine, and 7-speed auto transmission; Cadillac’s CTS-V Base model, including a standard 6.2L V-8 640-hp intercooled supercharger engine, and 8-speed automatic transmission with overdrive, and the Chevrolet Camaro ZL1, with a standard list that includes a 6.2L V-8 650-hp intercooled supercharger engine, and 6-speed manual transmission with overdrive.

At another point on the 2017 model year spectrum, the Mercedes-Benz AMG CLA45 Base features AMG 2.0L I-4 375-hp intercooled turbo engine and 7-speed auto-shift manual transmission, the 155-hp, SKYACTIV-G 2.0L I-4 Mazda MX-5 Miata RF Club, sporting a 6-speed manual, and the MINI Hardtop John Cooper Works that comes standard with a 2.0L I-4 228-hp intercooled turbo engine and 6-speed manual transmission.

To put those above specs in perspective, consider the Bugatti Veyron Super Sport, called the fastest road car and most powerful production car ever (launched in 2010): 1,200-hp, maxim
um torque 1,500 Nm, acceleration from 0 to 100 km/h in 2.5 seconds, top speed of 415 km/h.

Now comes ‘son of Veyron,’ the world’s newest “most powerful, fastest, most luxurious and most exclusive production super sports car: the “quintessential ultimate super sports car” (Bugatti’s descriptor), Bugatti Chiron: 1,500-hp, 16 cylinders, 4 turbochargers. $2.5 million.

 

Challengers, anyone?

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