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Old 04-17-2004, 03:09 AM   #31
DodgeRida67
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I'm gonna ask you a very simple question now...how old are you and how many years experience do you have with cars? because I know that most people here, that you are calling ignorant, have atleast 15 years behind them




I don't care if you are a damn car, if your wrong, your wrong. Deal with it. Screwy people
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Old 04-17-2004, 03:15 AM   #32
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http://www.ankn.uaf.edu/VS/magneto.html


There, check that out. I'm going to stick with this until you fools learn the most basic crap.


Incase your slow to read that site I sent you, and stop at the first few sentences, I'll quote the point.
Quote:
Zap! The spark plug sparks. The first droplets of gasoline are ignited by the heat of the spark. They ignite the ones next to them, and in a chain reaction, they ignite the ones next to them. The expanding gasses that result from the ignition of the gasoline forcefully drive the piston downward.
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Old 04-17-2004, 03:16 AM   #33
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Quote:
Originally Posted by DodgeRida67
I don't care if you are a damn car, if your wrong, your wrong. Deal with it. Screwy people
Dont get me wrong, I love cars...but not to the extent that I am one
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Old 04-17-2004, 04:03 AM   #34
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Ya know what ? I think eveyone got lost in this thread What was the question ?
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Old 04-17-2004, 04:06 AM   #35
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The spark has lots of voltage. It gives the energy needed to make the fuel combine with the air.

Yes heat is created. But it's the energy from the spark that starts the reaction. A spark plug is not a glow plug.

as per my previous example, hot coals have a lot of heat, but failed to ignite the gas. the spark gives the energy needed to activate the fuel/air reaction

You called the spark Heat. The spark itself is not heat and does not ignite the gas because of it's 'heat'.

you should agree that a spark is electricity. Electricity is not heat.

Heat: A form of energy associated with the motion of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation.

Electricity is not the motion of atoms, but of electrons. Electricity can cause atoms to move and vibrate. Hence, how a toaster works.


does that explain things enough or should we go on?
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Old 04-17-2004, 04:08 AM   #36
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Quote:
Originally Posted by DodgeRida67
http://www.ankn.uaf.edu/VS/magneto.html


There, check that out. I'm going to stick with this until you fools learn the most basic crap.


Incase your slow to read that site I sent you, and stop at the first few sentences, I'll quote the point.

How to win freinds and influence people, and get your ass kicked at the same time///in my world.
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Old 04-17-2004, 04:38 AM   #37
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Although written towards two cycle engines, this is a well written simplified discussion of what I was referring in a couple of my engineering texts

The bottom line here is a plug gapped 0.01 inch wider than spec may not create a spark with enough energy to ignite the lean fuel air mixture under 150 psig pressure, cause misfireing and the subsequent headaches
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Old 04-17-2004, 08:00 AM   #38
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Quote:
Originally Posted by lunatic987
The spark has lots of voltage. It gives the energy needed to make the fuel combine with the air.

Yes heat is created. But it's the energy from the spark that starts the reaction. A spark plug is not a glow plug.

as per my previous example, hot coals have a lot of heat, but failed to ignite the gas. the spark gives the energy needed to activate the fuel/air reaction

You called the spark Heat. The spark itself is not heat and does not ignite the gas because of it's 'heat'.

you should agree that a spark is electricity. Electricity is not heat.

Heat: A form of energy associated with the motion of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation.

Electricity is not the motion of atoms, but of electrons. Electricity can cause atoms to move and vibrate. Hence, how a toaster works.


does that explain things enough or should we go on?

Please refer to "LIGHTNING 101"
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Old 04-17-2004, 12:03 PM   #39
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A definition of heat from Websters Dictionary (http://www.m-w.com/cgi-bin/dictionary) e (1) : added energy that causes substances to rise in temperature, fuse, evaporate, expand, or undergo any of various other related changes, that flows to a body by contact with or radiation from bodies at higher temperatures, and that can be produced in a body (as by compression) (2) : the energy associated with the random motions of the molecules, atoms, or smaller structural units of which matter is composed f : appearance, condition, or color of a body as indicating its temperature

definition of spark from the same source: a luminous disruptive electrical discharge of very short duration between two conductors separated by a gas (as air) b : the discharge in a spark plug c : the mechanism controlling the discharge in a spark plug

What happens from an engineering and a physics perspective without going through the calculus to explain it is the spark is essentially a discharge of electrical energy. This electrical energy is converted to heat during this discharge since the air gap in the plug acts as a resistor since a certain energy at a certain voltage is required to ionoze the mixture ald allow the spark to form). The larger the gap, the more resistance or the more energy required and voltage required to ionize the mixture . The leaner the fuel air mixture, the more resistance. (the more energy required The electricity passing throgh this resistance is converted to heat energy similar to what happens on a stove when the electricity passed through the calrod element

Voltage gradient is what drives the electricity (similar to a pump driving water) The higher the voltage (30000V + in modern systems) the greater the gap the larger the gap the electricity can jump. If the voltage is not high enough the spark cant jump the gap hence why you don't overgap the plug unless the ignition system voltage is raised (the original question)

Energy is what lights off the fuel mixture. In theory, fuel air mix, as long as it is above the minumum required for combustion, does not care what the source is, as long as it is above the ignition temperature. What it does care about is it is at a certain level measured inorder between .00005 - .00010 joules (a btu is equal to a little over 1000 joules)

The reason for using a spark is simple - with the compression ratios involved in a spark ignition (SI) engine and the speeds a SI runs using a spark which forms and dissipates at the speed of light can provide the energy at the proper temperature and be timed precisely to fire at the right point to get the maximum power and efficiency from the engine
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Old 04-17-2004, 12:20 PM   #40
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I think weve beaten this subject to death

The bottom line here is a plug gapped 0.01 inch wider than spec may not create a spark with enough energy to ignite the lean fuel air mixture under 150 psig pressure, cause misfireing and the subsequent headaches

I've tried to use my 20+ years experience as a mechanical engineer to explain physically what is going on during the combustion process. My last response is a digression from the web site lectoid posted to help connect heat and energy and tie the concepts together.

It is not an emotional issue to me. Science, physics and engineering is just that - science, engineering, and physics. These concepts as they apply to cars are not new - They are discussed in a text someone gave me dated 1927 thus in my mind are time tested and true

I am finished arguing this subject. I think the facts have been stated in a simple manner where the target audence of the forum understands.
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Old 04-17-2004, 03:05 PM   #41
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PLease don't waste your time arquing. Your flat wrong.



Incase the last site didn't get you there, heres a very in-depth explination of spark plugs.
http://www.stealth316.com/2-sparkplugtech.htm


and heres the main point I want you to read from it:

Quote:
Electrical Characteristics
The spark plug's primary function is to generate a spark across the gap between electrodes in order to start the combustion process. Combustion is initiated by the flame kernel created from the heat and gas ionization caused by the electrical energy of the spark. The voltage necessary to produce a spark is called the required voltage. It is the job of the ignition system to provide sufficient voltage to the spark plugs, called the available voltage, at the correct time during the compression stroke (typically 5 to 30 degrees before top dead center, BTDC). If the required voltage exceeds the available voltage then a misspark or misfire occurs, that is, there is no spark. If the available voltage exceeds the required voltage then there is a voltage reserve, and the spark occurs when the required voltage level is met. The factors that affect the magnitude of the required voltage are discussed here, along with the wasted spark system used.
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Old 04-17-2004, 05:48 PM   #42
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Combustion is initiated by the flame kernel created from the heat and gas ionization caused by the electrical energy of the spark




Listen up class. Today if you understand this lesson you graduate from 1st grade.

#1 notice the "spark" is called a flame kernel. I wonder why...OH YEAH. I know why. Thats why were here.


#2 heat and gas ionization caused by the electrical energy of the spark

Energy is not create or distroyed. It is converted. Electrical energy CAN NOT DO CRAP towards igniting fuel. When it jumps the gap the electrical energy is CONVERTED to heat. That ignites the fuel.


If you understand this class, you then can move on. Otherwise....

Last edited by DodgeRida67 : 04-17-2004 at 05:50 PM.
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Old 04-17-2004, 05:52 PM   #43
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Okay Bozo, just to humor you I'll play your silly game. On average, what is the temperature of the spark?
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Old 04-17-2004, 06:00 PM   #44
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Okay Bozo, just to humor you I'll play your silly game. On average, what is the temperature of the spark?




I don't know. Why dont you tell me? Stick your pea-sized head in a cylinder and find out




Edit: vwhobo, you fail.
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Old 04-17-2004, 06:04 PM   #45
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Originally Posted by DodgeRida67
I don't know. Why dont you tell me? Stick your pea-sized head in a cylinder and find out




Edit: vwhobo, you fail.
It's amzing not only that it took you 10 minutes to type that but also that with all your bullsh*ting you can't even answer a very basic question that would help to substantiate your theory. There must be a number, give it to us.

By the way, based on what you posted earlier, you have no concept of what a flame kernel is.
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