Cars+Group+1

Ethan and Norbert

Car Part: ENGINE When you put fuel into a confined space and light it on fire, the combustion reaction releases an extremely high level of energy. When harnessed, this energy can be used to do work in a machine. It is in this way that a car engine works.

Most car engines work on a four-stroke combustion cycle (demonstrated in the linked animation below). [|__Engine Combustion Animation__]

The first stroke is called the intake stroke. At this point, the intake valve opens and the piston moves down, allowing for air and gasoline to flow into the combustion chamber. It is important that both the air AND gas gets in as the oxygen in the air is necessary for combustion to occur.

The second stroke is called the compression stroke. In this part of the cycle, the piston moves back up, putting the gas/air mixture under extreme pressure. This added pressure is necessary to provide an even more explosive result.

The third stroke is called the combustion stroke. This occurs as the piston reaches toward the top of the combustion chamber. The spark plug in the engine emits a small spark to ignite the gasoline. The combustion creates such a large release of energy that it pushes the piston back down.

The last stroke is called the exhaust stroke. When the piston hits the bottom of the chamber, it triggers the exhaust valve which allows for the exhaust from the reaction to flow out of the tailpipe of the car.

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Most diesel engines work in the same fashion as the gasoline engines.

The difference is that the diesel engine does not have a spark plug. Instead, it intakes air and compresses it, and that it then injects the fuel directly into the combustion chamber (direct injection), unlike in a gasoline engine where the air and fuel are mixed before entering the chamber. The heat of the compressed air then lights the fuel.

The fuels themselves are quite different as well. A gasoline engine burns C9H20 whereas a diesel engine burns C14H30. Diesel is less refined than gasoline so it is heavier and evaporates at a slower rate. The really neat thing about diesel is that it has a higher energy density. On average, 1 gallon of diesel fuel contains approximately 155x10^6 joules, while 1 gallon of gasoline contains 132x10^6 joules.



These incredible chemical equations (C9H20 and C14H30) power our economy, government, and indeed our world!

**__ List your suggestions below: __**
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Julie, Cindy, Sarah - Explain what happens when someone "revs" their engine

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Alex - Show the differences between a regular gas engine and a bio fuel engine.

Katelynn and Amanda- explain how some of the different parts of the engine work together