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Home > Performance Mods > Engine Mods > Engine: The Internal Combustion Process

Engine: The Internal Combustion Process

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Orin


Reg'd: Dec 08, 2005


Engine



Before you modify your engine, you should really know just a little about what's going on under the hood of your car and how it all really works.

I am not an engine expert and compared to most people I'm still a noobie, but I'm learning and I'd like to share what I have learned with everyone.

Before we even get to talking about horsepower and blah, you've got to understand the heart of it all. The magic starts with the internal combustion engine.


The Internal Combustion Engine

It's called the internal combustion engine because this is where fuel and air is blown up to move pistons which in turn create rotational movement needed for everything else.

Although we now have computer controlled variable timing, better materials and even more computer controlled systems, the engine itself has not changed in over 100 years. The same thing that moved engines in older times is the same thing that moves your car today, fuel being blown up and moving an internal mechanism to create moving force.

Let’s get an understanding of how the internal combustion process works in relation to some basic modifications like air intakes, exhaust and a header..

The very first part of the whole combustion process is intake, I don’t mean cold air intake or short ram intake. I’m talking about the very basic of the basic, air being drawn into your combustion chamber. Oxygen in the air is part of the mixture you’ll burn or explode to create power.

We’ll call this step 1 in the combustion process as illustrated below:

Step 1: Intake-Air is sucked into the chamber



When you look at the illustration you can see the piston moving outward is drawing in air to be used for the combustion process. Turbo cars have compressed cool air being forced into the chamber… think of it as squeezing two 300 lb fat ladies into a telephone booth.. Never mind, I didn’t want to imagine that. Let’s not get too far ahead, we’re learning the basics.






Step 2: Compression--Air/Fuel is squeezed tight


The next step in the internal combustion process is called compression, this is where the mixture of fuel and air are squeezed or crushed together tight by the upward movement of the piston as illustrated in step two of the illustration



the tightly packed air/fuel is the step right before the magic, this mixture is exploded by the spark from your sparkplug. The spark from the plug has to be exactly precisely on time, if it’s off just by a fraction of a millisecond, the timing is ruined and you’ll have some pretty bad engine knocking and possibly other problems.

Remember the 300lb fat ladies in the telephone booth? Okay now imagine that booth being compressed even tighter, that’s why turbo cars use lower compression pistons.

N/A or naturally aspirated vehicles use higher compression pistons to squeeze the air fuel mixture as tight as possible to get the biggest bang.



Step 3: Combustion-The Air/Fuel/Compressed air is exploded

BANG!! BOOM!! That’s exactly it, fuel and air being mixed together, compressed, then a spark to blow it up. This whole process happens very quickly. The more air/fuel in the compressed chamber, the bigger the bang. The explosion sends the piston on a down downward thrust, aiding in the next step of the whole process. First, see the illustration again to see how combustion works.



The downward thrust creates the movement power to the crankshaft


Step 4: Exhaust-the waste must be let out

The nastiest part of the process, all the bi products of the fuel, smoke chemicals has to be let out of your engine.



This process is where your efficient exhausts and header comes into play, get that exhaust out quick and you relieve backpressure from your engine and in turn, you’ll help your engine be efficient.

Turbo cars burn up a ton of air/fuel mixture, so you’ve got to have a bigger pipe to relieve that massive amount of exhaust, a naturally aspirated vehicle doesn’t need as large of a pipe diameter.



^That’s an illustration of an in-line 4 cylinder engines, the whole process happens in fractions of one second.



Wrap Up

The engine is the actual part of your car that MAKES power, things like a header, cold air intake, exhaust, pulley, mid-pipes, s-pipes help the basic functions of your engine be efficient and in return frees up horsepower, but don’t be confused when it comes to hype about one brand claiming they make power. Only the engine creates power.

The engine functions very much the same way we do, it needs to draw in air and it must also be allowed to exhale.

Enjoy!
[#] Aug 19, 2007 10:43am
SqMK


Reg'd: Dec 31, 1969

Ultimate Window Washer

Nice writeup.

You can also get more information here:

http://auto.howstuffworks.com/engine1.htm

[#] Aug 19, 2007 10:47am
Orin


Reg'd: Dec 08, 2005




thanks, I'll edit this if something isn't clear enough
[#] Aug 19, 2007 11:01am
Mayo


Reg'd: Feb 14, 2007

The Guru

Great info! A good read for anyone who is still unclear as to how an engine works.


"I have an idea! An idea so smart, my head would explode if I even began to know what I was talking about." - Peter Griffin
-- Want to post a "For Sale" thread? Check out the rules first.
[#] Aug 19, 2007 11:50am
hvtopiwala


Reg'd: Jan 03, 2007

Godlike Advisor

i had a rough idea of how it works, but this clears alot of itup. thanks!

[#] Aug 19, 2007 11:52am

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