JovialJman - How Engines Work

"Beacause, engines never look the same when looked at to closely." - JovialJman

Without engines, we all would be driving around like in the cartoon of The Flintstones. pushing our heavy vehicles around and having massive legs, (who needs gym then). These wonderful pieces of machine are very complicated in its workings, so let's talk about that.

When talking about engines there are several kinds, so we shall concentrate on Gasoline and Diesel engines though as they are the some what in use of everyday lives of many. Both use explosions to push down a piston that turns a crank shaft producing rotational motion which is used in various ways and the end results are that the tires move to make the car move forward or backwards.

Since Petrol is the most common, from where I come from, I shall start with the Diesel engine. The engine has 4 strokes, or rather 4 different events that happen for one engine cycle to take place. Once in motion, the first step is that the engine needs air. So the crankshaft is turned lowering a piston, at the same time a valve opens up to let air from outside (or a turbine) which fills the cylinder. The inlet valve is then closed and the piston moves upwards, this compresses the air and thereby increases the temperature and presure of the air. Once the piston is at the top of the cylinder ,diesel is injected into this mixture by a nozzle, and since the air is at such a high temperature the diesel automatically ignites, which forces the piston down. Due to the residual momentme, the piston then comes up and the outlet valve is opened to let all the waste material out. Once closed the inlet valve opens and the process starts from the beginning again.

This Image shows the 4 stages of the diesel engine.

Since there is only one stage that there is force to turn the bar at the bottom, the power is not very uniform. To get more stable power there are four cylinders hooked up together to allow that, at any given time, there are all four strokes happening. This means that there is always a force pushing down on one of the cylinders, (the more cylinders you have, the more uniform the output power will be), thus giving a better driving experience, (this video along with this one explains, with use of an animation, how they work).

Petrol (aka gas) engine workings are very similar to a Diesel. There is also 4 strokes in the engine cycle but there are some that have 2 strokes, (mainly the older smaller vehicles, like older bikes). The 4 strokes are, first there is a air and fuel mixture that is sucked into the cylinder through an inlet valve when the piston moves down. The valve closes and the Piston moves up again. The mixture is compressed, but since petrol has a higher ignition point than diesel it has to be ignited, So the spark plug provides the ignition source and the mixture explodes which forces the piston down, (this is, again, the only stroke that produces power to the crankshaft) once it reaches the bottom the crankshaft turns it more and forces it up and the outlet valve opens, which takes all the waste material out. when the piston starts going down again, the inlet valve lets in a new air, fuel mix and the process repeats. It takes 2 revolutions to complete one cycle.

2 Stroke engines don't really have valves. When the cylinder moves down it draws in air through an opening. when the cylinder moves up, it goes past the hole, preventing the air-fuel mixture to escape, and it compresses it. The spark plug ignites the mixture forcing the piston to go down. on the way down an exit hole is reveals and the fumes escape, and when the piston continues down, the inlet hole is reveals again and a new mixture is sucked into the cylinder.

2 strokes have some advantages over 4 stroke engines, namely, since that have less parts, they can be lighter and produce more power for their size, but some of the disadvantages are that since there outlet whole and inlet hole are open at the same time, some of the fuel mixture escapes before being used, this means that it uses more fuel and is worse on the environment as there are more emissions as well. Because of the price of fuel, the 4 stroke is preferred as it is better for your wallet, (if you own a vehicle you shall understand).

Anyways, that is my discussion on the internal workings of 2 popular types of engines in our cars today. Electric Cars and jet engines shall be coming soon. Please let us here at TSCA know of any experiences you have had with engines, or if you preform petrol or diesel cars better down in the comments, on Facebook or over on Twitter, as we love to hear from you. Do you have friends that would like to be a mechanic, or just loves fire, please share this post with them as I am sure they would appreciate the thought. If you, yourself would like to see the newest post as they come out, please Follow us on Twitter, or like us on Facebook, using the associated buttons on the bar to the left, Thank you for taking the time ti read today's post, and I shall write again overmorrow.

Travel safe my friends.