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Therefore, one horse could produce 33,000

foot-pounds of work every minute. Horsepower is now a standard measurement for engine performance; you can use whatever combination of weight and distance you like as long as the product is 33,000 foot- pounds in one minute. In modern times, horsepower refers to engine power. Engines in race cars are much larger than those in street cars, which typically do not generate more than 300 horsepower. A NASCAR engine can be 5.87 liters compared to a regular engine of about 2.0 liters in an average car. Both

Scottish inventor James Watt came up with the concept of horsepower to measure the power of engines.

are internal combustion engines, meaning the fuel and air burn inside the engine to create the energy to move the pistons in the engine. When you hear the term “2.0-liter engine,” what does that really mean? As the piston moves, a certain amount of air is sucked in. That amount depends on the size of the cylinder and piston and the displacement (how far it moves) of the piston. If your car has a four-inch-diameter piston and it moves four inches up and down (the stroke), this means that one piston can suck in 823 cubic centimeters of air per stroke. If your car has four cylinders, multiply 823 by 4—that rounds up to a 3.3-liter engine. This means that turning the crankshaft of this particular engine, two complete revolutions for the four pistons would “inhale” 3.3 liters of air. This value is called engine displacement, and it indicates the maximum power that can be produced by the engine.

10 CONNECTING STEM AND SPORTS | AUTO RACING