Automobiles horsepower

Engine rating reflects industrial practice. Automobile engine rating is the peak horsepower developed on a test stand, whereas industrial engine rating is usually in terms of continuous load. 

When the automobile became preeminent in the early twentieth century, it did so with good reason. Wliether the energy to power a bicycle is anaerobic or aerobic in nature, it is still minuscule in comparison to what an automobile s internal combustion engine can deliver. In the United States, almost all subcompact cars are equipped with engines that can generate 100 or more horsepower (74,600 watts), and can sustain this output all day long. 

However, the effects from automobile exhausts in these cities are similar to those in industrial cities of advanced countries, because many vehicles have a high weight-to-horsepower ratio and are often old and poorly maintained. The horsepower of 85% of the cars in India is between 10 and 14, and 60% of all vehicles are more than 10 years old. Vehicle maintenance is poor because spare parts are expensive or unavailable, and technical competence is low. Consequently, pollution is out of all proportion to the number of cars in circulation. Carbon monoxide peaks of 100 ppm have been recorded at street level at major intersections. As the number of vehicles continues to increase, it is expected that oxidant pollution may become a problem in other cities if control measures are not introduced. 

It is obvious that the cured brake blocks must be very strong if they are to withstand the abuse that friction products must endure. The horsepower of an automobile may be as high as 50 to 100, but the brakes on the same automobile must be 400 to 600 horsepower if the brakes are to stop the automobile in one-sixth the distance required to accelerate the automobile, by its engine, to speeds where brakes are applied to stop the automobile. The major fraction of the kinetic energy of the automobile is suddenly converted to heat in the brakes, and the temperature may rise abruptly from 0 °F to 1000 °F in a matter of seconds. Thermal shock alone would destroy an inferior brake pad. 

There are times when the correlation between a specific parameter and the product performance is clear. For instance, in an automobile of a specific size and weight, the more horsepower the engine has, the faster the car can accelerate, and the higher its top end speed (Figure 5.2). 

---