How many of you have cars, I’m sure more than 80% do, but how many really know how the engine works, I’m gonna address just a small kind of engine, Gasoline non-electronical-injection engines. My knowledge is not wide about it but I’m going to share what I know.



The mechanics of an engine is not very complex, just a well timed and precise dance involving all parts to get the most of the combustion power of the fuel. The complex part is the thermodynamics of the process, as I had a low grade on that subject in the university (barely passed) I’m not gonna go further on it.



Im using some Wikipedia.org gif images to explain it better, mostly ‘cause I suck in flash and failed in my attempts to make good ones, and wikipedia’s are good enough ^^.



Engine Parts



Here are the main parts of the engine



Combustion Chamber

Piston

Intake and Exhaust Valves

Spark Plug

Crankshaft

Most car engines work on 4 stroke cycles:

Intake Stroke

Compression Stroke

Combustion Stroke

Exhaust Stroke

Engine dance

The first stroke starts with the piston on top, as the piston goes down the intake valve opens and lets in a mixture of Gasoline and Air. This mixture consists mostly of Air (around 80% or more in volume).

The piston then moves back to the top to compress the mixture; this compression helps the explosion to become more powerful.

As soon the piston is again at the top, the spark plug releases a spark and ignites the fuel and explodes forcing the piston to go back down with force.

As soon the piston has reached the bottom, it moves back up again and the exhaust valve opens to allow the combustion gases leave the body of the engine starting the cycle again.

Chemist Approach

A chemist doesn’t worry too much about the mechanics of the cycle, but the combustion phase of it.

Gasoline consists of hydrocarbons with between 4+ carbon atoms (up to 10 sometimes), most of them are aliphatic alcane hydrocarbons.

I will made a comparison with C4 (Butane) and C5 (Pentane) components of gasoline with some “Environment-friendly” substitutes of gasoline.

Regular Gasoline

Gasoline Substitutes





Natural Gas, that consists of Methane (C1) around 85%

Hydrogen

CO 2 is a pollutant, and its generated in high amounts by motor engines, as you can see in the reactions above, carbon dioxide is generated except on the Hydrogen combustion, the more amount of carbon molecules the fuel has, it generates more CO 2 .

Some countries started to use Natural Gas instead of gasoline, this a good choice because Methane doesn’t generate a high amount of CO 2 , BUT still it does generate some.

The perfect fuel in my opinion :D, Hydrogen, as you can see it generates none CO 2 .



