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Spark Plug Power

09/15/2016 2:30 PM

How many volts and amps does a spark plug requires before it ignites?

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#1

Re: Spark Plug Power

09/15/2016 2:33 PM
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#2
In reply to #1

Re: Spark Plug Power

09/15/2016 2:36 PM

How many milliseconds that happens?

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#3
In reply to #2

Re: Spark Plug Power

09/15/2016 2:49 PM

Burn time is about :

  • 1.0 to 2.0 ms is considered normal
  • 0.8 to 1.0 ms is shorter than normal, but depending on engine and ignition system design may be acceptable.
  • Less than 0.8 ms is too short and is indicating a problem
  • 2.0 to 2.4 ms is longer than normal but depending on engine and ignition system design may be acceptable.
  • 2.4 ms or more is too long and is indicating a problem

http://www.crypton.co.za/Tto%20know/Ignition/burn%20time.html

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#4
In reply to #3

Re: Spark Plug Power

09/15/2016 2:52 PM

Wow, awesome! Thank you!

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#23
In reply to #1

Re: Spark Plug Power

09/16/2016 9:25 AM

That may be an adequate firing current for a typical family car, but the twin magnetos on a top fuel dragster require 44 amps, or over 5000 times this in order to create a single ignition pulse.

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#5

Re: Spark Plug Power

09/15/2016 3:05 PM

Depends.

Are you talking about modern electronic ignitor old points and condensor or ancient magneto systems?

As SE said those values would be fairly normal for a modern electronic ignition but for the older mechanical points and condenser systems 8 - 10KV @ ~8 - 10 ma was pushing their top end in most applications.

Going back to the old magnetos they ran was lower. Many were at best good for 3 - 4 KV but easily packed a good 20 - 30+ ma punch.

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#6

Re: Spark Plug Power

09/15/2016 4:02 PM

A spark plug does not ignite, ever.

Electrical current, at some lower value, much lower than that described by the sources given by SE, the electrical current will arc (jump) across the gap from one side to the other to get back to ground potential.

At the lower levels, an arc will jump across the gap but will not have sufficient energy to ignite the air/gas mixture that is highly compressed by the piston.

So, technically, SE's sources do not answer the question, as posted.

Now, you may want to re-state the question.

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#7
In reply to #6

Re: Spark Plug Power

09/15/2016 4:33 PM

Well, some part of the spark plug might ignite, but turning whatever metal there into a fire with oxygen really takes some kind of high temperature, like about 1000 C or much higher, since the metal is not finely divided. The ceramic part, not so much.

As far as getting a spark, that is another issue. The values mentioned for various conditions by other posters such as Solar Eagle, Lyn, and Tornado have you covered for the electric spark aspect.

Getting fuel ignition is somewhat more involved, but hopefully linked to the spark.

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#8
In reply to #7

Re: Spark Plug Power

09/15/2016 5:37 PM

Is it just cynical me or do some more here feel we may be hearing from OP with more homework questions??

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#20
In reply to #8

Re: Spark Plug Power

09/16/2016 9:08 AM

It's homework.

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#9
In reply to #6

Re: Spark Plug Power

09/15/2016 6:07 PM

I am a bit confused now. Is it not called "ignition engine"? I mean, where does that term came from?

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#10
In reply to #9

Re: Spark Plug Power

09/15/2016 6:17 PM

It is called, and is, an "internal combustion engine".

The spark plug is a small part of the "ignition system' that causes combustion of the air/gas mix inside the cylinders of the engine.

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#25
In reply to #9

Re: Spark Plug Power

09/16/2016 9:57 AM

I would say "spark ignition engine" as opposed to "compression ignition engine" (Diesel.)

Going way back there are other types of ignition such as hot tube.

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#16
In reply to #6

Re: Spark Plug Power

09/16/2016 6:43 AM

Picking a nit of English grammar:

A spark plug does ignite (transitive verb, even if the object of the sentence fuel is missing)

In the same way, a spark plug delivers (transitive verb, with the missing object being a spark)

It is true, as others have posted, that ignite may also be an intransitive verb, as in:

If you supply sufficient energy to it, a spark plug ignites.

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#21
In reply to #16

Re: Spark Plug Power

09/16/2016 9:10 AM

Post rejected due to poor use of the word ignite, just stop with the semantics. The spark plug does not ignite, it delivers a spark, and I am about tired of people fudging with words.

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#24
In reply to #21

Re: Spark Plug Power

09/16/2016 9:30 AM

From the Merriam-Webster dictionary:

Full Definition of ignite

transitive verb

1: to subject to fire or intense heat; especially : to render luminous by heat
2a : to set afire; also : kindle b : to cause (a fuel) to burn
3a : to heat up : excite <oppression that ignited the hatred of the people> b : to set in motion : spark <ignite a debate>

intransitive verb

1: to catch fire
2: to begin to glow

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#32
In reply to #21

Re: Spark Plug Power

09/20/2016 11:39 PM

I think that our nation came up with the belief that it's okay to play with words when someone we know said "I never inhaled".

The damage that was caused by our previous leader not having the guts to admit his wrongdoing is still haunting us today and will continue to haunt us until we have an ethical leader who is willing to take the heat for his mistakes.

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#27
In reply to #16

Re: Spark Plug Power

09/16/2016 10:57 AM

I'm sure that the OP is in awe of your unparalleled command of the English language.

Personally, I believe your statement detracts from the conversation at hand and does nothing at all to impress me.

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#30
In reply to #27

Re: Spark Plug Power

09/16/2016 4:18 PM

Likewise your statements.

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#33
In reply to #16

Re: Spark Plug Power

09/20/2016 11:47 PM

I've learned that to communicate effectively, you must consider your audience. This is a site for engineers/scientists to share their knowledge and to help each other solve problems. If an overwhelming majority of people here do not believe a spark plug ignites, then that's what we believe.

Of course there are ways to ignite a spark plug ... just like there are ways to keep a Chevy Cavalier running.

Sorry, I had to throw that in.

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#34
In reply to #33

Re: Spark Plug Power

09/22/2016 5:48 AM

I've learned that to communicate effectively, you must consider your audience.

I fully agree with that.

This is a site for engineers/scientists to share their knowledge and to help each other solve problems.

The site is more than that. It is a site where someone less qualified than yourselves may pose a question and hope for an answer. The hope is that the answer is couched in understandable language. Now if you have codes of practice for engineering installations then you must understand that there are also codes of practice for the use of language. If I cite the Merriam-Webster dictionary as a source of word definitions then you will have to accept that authority or provide an alternative of equal stature.

The fact is that this "overwhelming majority" has got it wrong, and taking an overbearing attitude does not help. Indeed, "Listen, you have the smallest boat in the lake" (post #22) is the sure mark of a bully who has run out of reasonable argument and is resorting to abuse.

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#35
In reply to #34

Re: Spark Plug Power

09/22/2016 9:16 AM

I was not addressing you Mr. Know-it-all, and frankly, I find your level intellectual snobbery to be beyond annoying, and reaching to the level of nauseating in the fullest sense of the word.

If you go back and look at post #22, you will see it was replying to post #19 (not you), and you will notice that OP at post #19 was starting to get smart-mouthed.

Go go sit and spin, professor.

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#37
In reply to #35

Re: Spark Plug Power

09/24/2016 2:50 PM

James,

I have to say I respect you as an engineer, and consider myself informed by your input into such topics as steam turbines (another thread). However, that respect does not extend to your attempted put downs here of both the OP and myself. In the field of vocabulary you are clearly not as informed as you are in the field of engineering, and you should by now recognise that.

I may say that I have spent my professional life (medicine) in talking to people of little understanding. I have found that I needed to be very precise in my choice of words. I would always prefer one-syllable words over two-syllable words. Any medical English I would decode into English English - thus "intravenous nutrition of the patient" becomes "putting a tube into a vein so that we can feed him". If the person I was talking to was American then I would try (not endeavor) to use US English. If I did otherwise the unhappy person could simply say "B***dy doctor didn't tell me a thing".

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#39
In reply to #37

Re: Spark Plug Power

09/24/2016 3:10 PM

I see what you mean. Enough said. K?

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#36
In reply to #34

Re: Spark Plug Power

09/24/2016 12:30 AM

I'm going to shift the conversation a bit, because I don't want to write something that may be taken wrong.

I wear a lot of different hats, therefore I use different forms of communicating. Some of my clients are entrepreneurs and I speak to them in a creative business manner. Other clients are executives and I cut the small talk down to a minimum and give them an executive overview. Many of my clients are regular folks and I can tone things down a little. I speak to men differently than women. I speak to people my age differently than seniors or millennials. I speak to my town council in a much more professional manner. I speak to my school board in a more educator tone. I speak to my laborers in a simpler way. And when I write here, I love it, because it allows me to communicate in a very precise manner based on facts and theories/hypothesis'.

You have to remember that as an engineer, we do see things as scientifically correct and incorrect. Like one of the other posts where a cell is called a battery (a battery is two or more cells). Or as in this post, where the OP asked about igniting a spark plug. Yes, I think we all know what he meant, but I thought it was funny to make a joke about it. I hope that I didn't offend anyone with my humor. I also hope that I didn't offend you either.

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#38
In reply to #36

Re: Spark Plug Power

09/24/2016 2:51 PM

Thank you. You make my point exactly.

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#11

Re: Spark Plug Power

09/15/2016 8:37 PM

For gasoline, about 30 mJ of energy.

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#12

Re: Spark Plug Power

09/15/2016 10:33 PM

Dear Mr.gutmonarch,

The voltage required for generating an electrical spark in the engine depends upon the Pressure inside the cylinder. About 40 years back, the compression ratio was 7:1 and the volts used was 6500 provided by revolving magneto.

The spark generated depends upon the gap between the electrodes.

The modern system is of static type and more efficient and voltage can be obtained as high a 10,000 volts.

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#13

Re: Spark Plug Power

09/16/2016 12:05 AM

There are a few ways to ignite a spark plug.

1. Throw it in an active volcano.

2. Place it on the exterior of an object entering our atmosphere.

3. Send it to the sun.

There are a lot of very smart people on this site who could give you a few more ways to ignite a spark plug.

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#14

Re: Spark Plug Power

09/16/2016 1:18 AM

It's the fuel that ignites, not the spark plug!

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#15
In reply to #14

Re: Spark Plug Power

09/16/2016 1:58 AM

Not true.

See my post on ways that you can ignite a spark plug.

In fact, I have another - I'm not sure, but it could work. Oak Ridge Labs has an accelerator that can generate 25MV. I wonder ... https://www.phy.ornl.gov/groups/accel/accel.html

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#19
In reply to #14

Re: Spark Plug Power

09/16/2016 8:41 AM

So, tell me what ignites the fuel? Maybe, some lawyers can answer this?

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#22
In reply to #19

Re: Spark Plug Power

09/16/2016 9:15 AM

Listen, you have the smallest boat in the lake. Do you really want to come in here and tell us? Do you really want to make my day? Do you really, really want to make waves? Is that your final answer?

What ignites the fuel is (1) compression to the autoignition point (diesel engine), (2) shock wave (ramjet engine, and possibly some other where supersonic shock wave ignites the fuel, or (3) plasma from a spark with sufficient energy content to start combustion of fuel-air mixture.

The G double D spark plug does not itself ignite, so get over yourself.

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#29
In reply to #14

Re: Spark Plug Power

09/16/2016 11:38 AM

See #16 and #24

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#17

Re: Spark Plug Power

09/16/2016 8:20 AM

No spark will jump the gap unless the gap is ionized, this takes place due to the voltage/pressure of the current. The volts required depend on compression ratio/cylinder pressure, density of the charged mixture and temperature to some degree and for sure the size of the gap. A faulty coil will jump 0.20 gap but probably not a 0.65 gap also the arc must have enough energy to cause ignition for instance a red spark has much less ignition potential than a blue coloured spark. There is much more for instance a CD ignition has a very high voltage spark but of short duration where as what was called a Transistor ignition had a longer timed spark that was fatter in appearance than the CD spark but arced for longer time interval. Both had their advantages and disadvantages.

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#18

Re: Spark Plug Power

09/16/2016 8:26 AM

The voltage required to jump the gap depends on the size of the gap. The wider the gap the higher the voltage. It will also depend on the type of plug as some have a resistor built in. One other consideration is the wire leading to the plug as some are solid core and others resistor wires. The longer the resistor type wire the higher the voltage required.

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#26
In reply to #18

Re: Spark Plug Power

09/16/2016 10:33 AM

I don't believe the resistance of the plug or it's wire matters. The voltage generated by the ignition system is all available at the plug end to initiate the spark. The purpose of the resistance is to limit the current and therefore the EMI that can bother the radio and other electronics of the car.

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#28
In reply to #26

Re: Spark Plug Power

09/16/2016 11:17 AM

I suspect a top fuel ICE with the big magnetos does not care about radio reception for the 3-4 seconds running the strip.

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#40
In reply to #26

Re: Spark Plug Power

12/27/2016 5:06 PM

Resistor wires came into play because the the RFI noise played hell with a cop's speed radar! Automaker's didn't care about your AM radio reception, they were forced to make the change. It's been years since I ran solid (copper) core wires on the street but I did get pulled over a few times and threaten because of the RFI noise on their radar back then. Not sure of the effects of solid core wires on the "new frequency" bands of the police radar? Anybody have some in-sight or got pulled over lately for running solid core wires?

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#41
In reply to #40

Re: Spark Plug Power

12/28/2016 11:36 AM

Old memories; in the 50's my hot rod buddies would tie the high tension lead to the radio antenna (disconnecting the radio, of course) to mess with the cop's radar. I don't know if it had the desired effect, but it sure screwed up everyone's reception at a car hop joint.

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#42
In reply to #40

Re: Spark Plug Power

01/11/2017 4:35 AM

Much of the new radar is actually Lidar. Since it works off of light (laser), I don't see how RFI noise could have an effect, but I could be wrong.

I believe for Lidar to work, the unit needs to be fixed (not moving) and the officer must point the gun at the target vehicle. I was told they aim at something large and flat like a license plate.

A few years ago, I received a ticket for speeding. The office hit me with Lidar, but I think he got another car, because the speed he told me I was going was pretty far off. The reason is because I don't have a front plate on my car and my front bumper is very curved (Porsche Boxster) and it's not a good place to shoot Lidar at. If he moved his arm a little (up or down), the place on the bumper/fender/hood would change and the reading would be incorrect. Of course, the court didn't like my response and found me guilty. Another lost day in traffic school!

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#31

Re: Spark Plug Power

09/16/2016 4:31 PM

How much wood, would a woodchuck chuck, if a woodchuck could chuck wood?

Why are you suddenly interested in spark plugs?

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