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

Engine: The Internal Combustion Process

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Orin
Auburn
Alabama, US
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
Atlanta
Georgia, US
  • Ultimate Window Washer
 Nice writeup.

You can also get more information here:

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

Hello guys I am new here and am looking for friends
[#] Aug 19, 2007 10:47am
Orin
Auburn
Alabama, US


thanks, I'll edit this if something isn't clear enough
[#] Aug 19, 2007 11:01am
Mayo
Rockville
Maryland, US
  • The Guru
 Great info! A good read for anyone who is still unclear as to how an engine works.


"gonna wash my car before i take a nap.. can't rest well knowing i've got the entire cast of A Bug's Life on my bumper" - Vicious
-- Want to post a "For Sale" thread? Check out the rules first.
[#] Aug 19, 2007 11:50am
hvtopiwala
Winter Park
Florida, US
  • Godlike Advisor
 i had a rough idea of how it works, but this clears alot of itup. thanks!

[#] Aug 19, 2007 11:52am
Ace83
Texas, US
  • Oil Changer
 its really nice to have that information in here, that would make it easier to understand whats going on the motor..

especially for those who want to understand more about tuning, especially spark timing thats a good aid in there, it would even be better if those comes with a comparison between a retard spark event and an advanced spark event like perfectly timed at the top dead center.. and also a preignition/knock/detonation event! lol i might be asking too much but thats great to have so people will understand it faster

Tsudo N1 cat back for sale w/ aero resonator
http://www.scionlife.com/...e2d8393ecb547f8ef5ef8f98e

Parts for sale!

http://www.scionlife.com/...p?t=242734&highlight=

http://www.yoursciontc.com/forums/index.php?showtopic=26297
[#] Dec 12, 2008 09:10pm
ae86pandadude
Avondale
Arizona, US
  • Oil Changer
 i would like to make a note to step 3... its not really a bang but we think of it as a bang. what really happens it the spark plug starts to make the fuel burn, not explode... it the fuel were to explode, it would cause pinging in our engines... there's a movie somewhere on the internet of some university or something that was able to get a camera to see all of the events that happen in the cylinder.

[#] Dec 13, 2008 12:55am
ae86pandadude
Avondale
Arizona, US
  • Oil Changer
 found the video and sry but i havent learned yet how to make it appear in the thread

4 stroke engine

[#] Dec 13, 2008 01:00am
Web
Maryland, US
  • THE SHADOW
 I don't believe any of that.....even the diagrams. My engine runs on pure rice power so blah!


[#] Dec 13, 2008 08:40am
Orin
Auburn
Alabama, US
^seriously, I've upgraded my engine to run with electromagnets through some diagrams purchased off eBay and now my car gets unlimited fuel economy.
[#] Dec 13, 2008 08:53am
Ace83
Texas, US
  • Oil Changer
ae86pandadude wrote:
i would like to make a note to step 3... its not really a bang but we think of it as a bang. what really happens it the spark plug starts to make the fuel burn, not explode... it the fuel were to explode, it would cause pinging in our engines... there's a movie somewhere on the internet of some university or something that was able to get a camera to see all of the events that happen in the cylinder.


the video you showed is nice.. but yeah bang is just a way of description.. it is sure very similar to an explosion some even say its actually an explosion.. the whole cycle happens in a fraction of a second even on low rpms, rapid and precise combustion of compressed air and fuel.. if you see it in real life that literally is an explosion (controlled) and the nice video is just a slow motion..

pinging like you mentioned happens when the gas/fuel mixture ignites (explodes) before the stroke cycle is completed like before the Top Dead Center.. Imagine the piston still rising from the previous cycle but the mixture is already exploding and push the piston oppositely downward.. that will destroy the pistons, rods, headgaskets and other internals. Preignition/detonation/pinging/knock are caused by several factors that causes uncontrolled burning of the mixture

Tsudo N1 cat back for sale w/ aero resonator
http://www.scionlife.com/...e2d8393ecb547f8ef5ef8f98e

Parts for sale!

http://www.scionlife.com/...p?t=242734&highlight=

http://www.yoursciontc.com/forums/index.php?showtopic=26297
[#] Dec 13, 2008 09:30am
crush02342002
US
  • Tire Changer
 id also like to add that pre detonation (pinging) can be caused by excess heat and excessive timing advancement. Also high air/fuel ratios can do this aswell. Normally its not that big of a concern when dealing with some bolt on parts (ie..intake,exhoust,header,pullys..ect) but when it comes to forced induction thats one of the main focus points one wants to address.

[#] Dec 13, 2008 03:25pm

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