Cars 101, episode 1: Basic Engines for Dummies.

[YF19pilot]

Welcome to the first itteration of what I hope to be a weekly discussion of how cars work. These presentations are for, but not limited to, the education of the less informed about the technology under the hood and the presentation of new and alternate technologies that may be changing the face of the automotive industry.

The way this works is simple, I post a basic topic and you all can ask questions or add to the discussion. I ask that you keep everything as simple as possible. If a 13 year old visiting this site who doesn't know Mazda from Maseratti can't understand what you're saying, you're being too complicated.

So, for the inaugral "issue" of Cars 101:

The Internal Combustion Engine


The first distinction to be made about a car engine is that it is an "Internal Combustion Engine". Defining these terms seperately:

Internal -- Inside

Combustion -- To burn.

Engine -- A device which is used to power or operate a larger system such as an automobile.

So in simple terms, we have a device that uses explosions made inside itself to create power or work. The simplest explanation of how it works, is that an engine of this type will take fuel into a chamber called a cylinder. Inside each cylinder is a piston which squeezes the fuel. When the fuel is fully compressed, it is ignited, causing an explosion. The explosion forces the piston back down, creating power.

Is there an External Combustion Engine? Why don't cars have those?

The best example of an External Combustion Engine is a Steam Engine, like those old locomotives. They use fuel to boil water into steam in a large tank known as the boiler. From the boiler, the steam travels into a large cylinder, and like the Internal Combustion Engine, pushes a piston, creating power. The problem with steam engines is size. A much larger steam engine is required to produce the same amount of power as a normal car's engine.

Okay, so I'm not retarded, but how does an engine actually work?

The typical automotive engine is a "4-stroke" engine. That is, the piston moves four times in one combustion "cycle". One cycle is down, up, down, up, and then the process repeats itself.

The first down-stroke is known as Intake. In this time, the intake valve for the cylinder is open, letting in a mixture of air and gasoline, while the piston travels to the bottom most point, known as Bottom Dead Center.

Once the cylinder reaches Bottom Dead Center, the intake valve closes, and the piston begins it's first up-stroke, known as Compression. In this time, the piston squeezes the air/fuel mixture.

When the piston reaches about Top Dead Center -- the highest point in it's stroke -- the Spark Plug creates a spark that ignites the mixture, causing a small explosion. The explosion expands at a rapid rate, helping to push the piston down. This down-stroke is known as, well, Combustion or Expansion.

When the piston reaches Bottom Dead Center again, the exhaust valve opens up, and the piston pushes the smoke out of the cylinder.

So how does the power get from the piston to the wheels?

I was just getting to that. The piston, or piston head depending on who's talking, is conected to a Piston Rod. The Piston Rod takes the up-down motion of the Piston and uses it to rotate the Crankshaft. From the Crankshaft, power goes through Drive Train to the wheels. The Drive Train is something to be explained later.

The Crankshaft itself is connected to one or more Camshafts which are used to operate the valves in each cylinder.


That, is the innerworkings of a car engine simplified.

The floor is now open for questions, comments, answers, and the inevitable overcomplicating of the system.

Next Week's topic: 2-stroke, 4-stroke, 6-storke, Rotary and other ways to make cars go.


Helpful links for this and other topics:

bone tries to explain superchargers: http://forum.finalgear.com/viewtopic...760&highlight=
bone had a question about diesel engines, helpful link inside: http://forum.finalgear.com/viewtopic...747&highlight=
Rotory engines: http://forum.finalgear.com/viewtopic...265&highlight=
a thread about some interesting 4-stroke alternatives: http://forum.finalgear.com/viewtopic...268&highlight=
josty explaining turbos: http://forum.finalgear.com/viewtopic...744&highlight=
josty had a question about diffs, and bone tries to explain (agian): http://forum.finalgear.com/viewtopic...900&highlight=
mgkdk explains the importance of displacement, leading into other discussions:
http://forum.finalgear.com/viewtopic.php?t=9381[/i]

[SL65]

Cars 101 a good idea

All my friends and family know I'm a car nut however if they ever ask me how a car works, I'm stumped I'v still got heaps to learn about cars cos all I'm good with is the electronics inside and how fast they go

Good idea! I just think you should BOLD the questions aswell as just putting them in ITALICS. It will look better.

[BerserkerCatSplat]

Not sure about other parts of the world, but what you've called a "Piston Rod", we call a "Connecting Rod."

Minor thing, I know, but I'd like it to be as accurate as possible.

I'm going to try and hunt down some pictures you can use for visual support of the drivetrain.

Good work so far!

[mautzel]

Nice idea - have no problem with the things described so far, but as soon as it gets advanced I'll be able to pick some things up for me as well.

[freerider]

Why not add sites from outside the forum?

howstuffworks.com This has animations and is very easy to read.
Explaining different types of engines (V, inline)

If you need more, just ask.

Greetz Johan

[bone]

caus by posting links to other sites, you kill the discussion

every question can be answered with "go look at howstuffworks.com", and we're back where we started.

if a discussion has to evolve, it has to start by a self written text

[Z102]

Originally Posted by YF19pilot

The Internal Combustion Engine


The first distinction to be made about a car engine is that it is an "Internal Combustion Engine". Defining these terms seperately:

Internal -- Inside

Combustion -- To burn.

Engine -- A device which is used to power or operate a larger system such as an automobile.

That's what I call going back to basics . But I think this is a great idea. I have a basic idea of how an engine works, but things like rotary engines, or how a turbocharger works I don't understand so well. I think I'm going to enjoy this thread

[YF19pilot]

Originally Posted by BerserkerCatSplat

Not sure about other parts of the world, but what you've called a "Piston Rod", we call a "Connecting Rod."

Minor thing, I know, but I'd like it to be as accurate as possible.

I'm going to try and hunt down some pictures you can use for visual support of the drivetrain.

Good work so far!

Ah thanks. I'm also thinking of doing some drawings myself, but if anyone can find good pictures and animations that will be helpful, let me know. And don't forget the source, I don't feel like stepping on too many peoples' toes.

Also, if there's any requests for certain topics, feel free to PM me.

[Cactus]

Originally Posted by YF19pilot

Welcome to the first itteration of what I hope to be a weekly discussion of how cars work.

Wheee! Greatest. Idea. Evar.

Looking forward to the episode on transmissions, for some reason I've always been fascinated by them, and it's only half a year ago that I finally got to understand how exactly a gearbox works, when I went to a tech museum with a fellow gearhead

[M3lover]

Great idea!