The Internal Combustion EngineAlmost every vehicle on the road today is powered by some version of the four-stroke internal combustion engine patented by Nikolaus Otto in 1876. Otto exploited the discoveries of the French physicist Sadi Carnot, who showed in 1824 that the efficiency of an engine depends critically on the temperature difference between a "source" of hot energy and a "sink" cold. The four-stroke engine compresses an air-fuel mixture and ignites it with a spark, creating a short-lived but intense heat source. Its portable efficiency has not been equaled since (Moyer). To fully appreciate the internal combustion engine, you need to know its origin and evolution, its modifications and the many improvements that have been made to it throughout its history. The internal combustion engine (ICE) is very important to human life and is one of the greatest inventions in history. Without it, people who travel long distances for work would not be able to get to their jobs; and travel would be almost impossible in bad weather. “Combustion is the engine of the economy of developed countries. Transportation is the second largest consumer of energy after industrial use in the United States and accounts for approximately 60 percent of our nation’s oil consumption” (Manly). The four-cycle ICE developed by Nikolaus Otto was not the first attempt at ICE. , but it was by far the best of its era. “It was [Nikolaus] Otto's four-stroke design that transformed the internal combustion engine into a viable means of transportation for the masses” (Automobile). As its name suggests, it operates on a basic four-stroke system: intake, compression, power and exhaust, that is: fuel mixes with air in the combustion chamber, or piston ; the mixture is compressed by the piston and ignites... middle of paper ... the transmission has up to six forward gears, which helps extend engine life and reduce gasoline consumption » (Automotive). Upgrades are often used to improve an automobile or engine. An upgrade can be defined as: the improvement of something, in this case an ICE… An upgrade can be as simple as replacing a part with a newer, better model of that same part. For collectors, for example, an upgrade might involve replacing existing collectors with larger collectors or collectors made of a different material that won't clog as easily; basically, they make the engine run better and last longer. Knowing where the internal combustion engine came from, how it can be modified, and how it has been improved will give a better appreciation of the internal combustion engine. The internal combustion engine is something that humans could not live without and yet it is constantly taken for granted.