Quote:
Originally Posted by John Strenk
I know there was a spark gap system that was used on some stuff with a oil problem. Instead of a dirty/wet plug missfiring because it was bleeding away the current all the time the coil was 'charging' but i don't see how it would work with a distributor.
The way it worked was there was a gap in the device that allowed the voltage to build up and when it fires, it fired across the gap in the device and the gap in the plug. I use to get lawn motors started by holding the spark plug wire a a little way off the plug and keep it running until the extra gas was burnt off the insulator on the plug.
Speaking of plugs, I just changed the plugs in my Liberty for the first time. 110,000 miles and 0.080 gap later it was still working. Never misfired. I like having the coil right on the plug.
|
Well, that's the deal,
The AIR GAP determines the voltage the coil has to produce to ionize the gap in the system,
Larger the gap, the more voltage for ionization the coil has to produce to ionize, then jump the gap.
You can't get the 'Storage' guys to understand there is no 'Storage', just transfer amperage at the primary winding for magnetic field,
Then transfer the magnetic field for VOLTAGE (instead of amperage) at the secondary winding.
Since you are limited by a SINGLE COIL, multi cylinders,
You only get 'X' amount of time for the coil to build POTENTIAL, Ionize the gap, make the spark happen, and get on with saturating the coil again for the next cylinder.
With coil on plug, that coil gets 4x time to saturate, then it gets 4x the time to make the spark before it needs to be in operation again.
Guys see 'oscillations' in spark energy patterns and think there is 'Storage' going on there,
When it's actually a coil that didn't have time to fully deliver the spark pulse to the spark plug gap,
And the oscillations are the left over, and wasted, magnetic field still moving around.
The ignition engineers figured that out, now we have coil on plug for the increased spark energy...
I'm not the 'Genius' that came up with it, I just follow around the guys with the great big brains and have them explain it to me... Using small words...
"Plasma" is the 4th state of matter, and every electrical spark is 'Plasma',
The problem with 'Plasma' is the more of it you make, the higher the heat and ionization, and the more material gets burned away or transferred in the process.
The race for spark plug material, like platinum, that will take the heat/transfer better is on, and there just isn't anything that will stand up to 'Plasma' we know of... YET...
So far, the ONLY way to contain a 'Plasma' WITHOUT having the material that it contacts burn away (Vaporize) or transfer from one 'Pole' to the other is a magnetic field.
No physical material contact, so no transfer/burning...
Since the magnetic field to contain 'Plasma' has to be about the size of a super collider and take HUGE amounts of energy to generate,
I don't think we are going to see high plasma ignitions anytime soon that don't consume everything they come into contact with...
They can use it as a 'Catch Phrase' or 'Buzz Word' if they want to, and are doing that very thing right now,
But an actual sustained Plasma storage or sustained plasma discharge for an ignition is a long way off,
And since it requires more energy to contain plasma than any gasoline engine can produce... Well, you get the idea...
By the time they come up with something that can produce and contain plasma in a 'Tank',
We'll have those anti-gravity flying cars and gasoline engines will be museum pieces if they exist at all...
Right now, we can crate a very weak, very small plasma ball in a spark gap for only a few milliseconds,
The only SUSTAINED plasma reaction we know about are STARS!
Our own sun is a very small, very weak self sustaining plasma reaction.
I don't think we are going to have anything that powerful under the hood in a canister anytime soon!
And if we did, what would be the point of having an internal combustion engine if we had that much portable power in a 'Canister'?
--------------------------
SO!
Buzz words aside,
You 'Dwell' time, the time the coils builds magnetic field,
Is about 30 crankshaft degrees (30 Degree 'Dwell Angle')...
In a V-8 engine, half the cylinders firing per revolution, that's 120 total degrees of 'Saturation' or 'Dwell Angle'
30 degrees x 4 cylinders = 120 crank shaft degrees.
(I wish I had a program here to do a pie chart, dwell 'Angle' is best demonstrated as a 'Pie' slice)
That's 240 crankshaft degrees of 'Ignition' or 'Induction' time for the magnetic field to collapse through the secondary windings and INDUCE a secondary electrical potential.
360 crank degrees - 120 Saturation Degrees = 240 secondary induction degrees,
240 secondary induction degrees ÷ 4 cylinders = 60 crank degrees for secondary induction to happen for each cylinder.
Your crankshaft is only in position for about 20 crankshaft degrees for a spark to do any good getting the fuel mixture to light...
And you have to consider Switching Time, which 'Ramps', so that takes up some of the spark energy production time,
And you have to consider 'Rise Time' where the collapsing magnetic field is INDUCING a secondary electrical current POTENTIAL (not a current yet since it's not moving, and what people mistake for 'Storage'),
So that takes time...
And then there is the 'Ramp Angle' time where the magnetic field is no longer collapsing, so it's not producing any secondary induction,
But it's not exactly expanding either since there isn't enough current getting to the primary windings to make the magnetic field expand at any substantial rate...
And at higher crank speed, you have to consider crankshaft velocity in it's rotation,
So you wind up with about milliseconds (or Micro Seconds if you didn't switch to the metric system)
At 5,000 RPM to get that flame front started so the engine will produce power in the 'Sweet Spot' of the 20 degrees of crankshaft proper position,
SO, with about 13 or so micro seconds
----------------------
(MicroSeconds, 1/1,000,000 of a second, expressed as 'uS')
Now, did you ever wonder why coils are rated for duration of secondary spark time in 'uS' or 'Micro Seconds'?
Instead of 'mS', Milliseconds, or 1/1,000 of a seconds?
Typical Coil Specification Blurb...
I was taught in school to believe 'Milli' and 'Micro' were the same things,
Just the English and Metric versions for the same thing... Which is dead wrong...
'mS' and 'uS' weren't ever discussed,
If they were, we would have noticed the difference and asked questions!
-------------
You have to consider the SPEED OF ELECTRICITY into the equation,
Since faulty cap, rotor, plug wires, plug conductors will IMPEDE (Impedance) the electrical current flow once the spark gap ionizes...
And as the number of plugs fired goes up with RPM,
The conductors in the system, coil windings, coil wire, rotor, plug terminals, plug wires, plugs heat up,
And they produce more resistance to the electrical current trying desperately to get through...
More resistance means more losses, and slower ionization times at the plug gap, so IMPEDANCE to the electrical flow to the plugs is also a consideration...
You have a VERY narrow window to get the PEAK SECONDARY POTENTIAL to the spark gap and make it do something it REALLY doesn't want to do...
Which is make an strong, hot arc in the plug gap...
And you have about 13 MILLIONTHS of a second (13/1,000,000 Second) to get it there and make it do the job you want it to do...
Now, you are tying to get all this done, as the POTENTIAL is dropping like a brick with RPM increase.
Increase in engine speed means LESS saturation time, and LESS secondary Induction Time...
So the POTENTIAL for the secondary spark energy is dropping like a brick, and you have a LOT less POTENTIAL energy,
And actual energy at the plug gap, to do the job with, while you are having to do it faster and faster as RPM increases and time between firings DECREASES...
I love it when the guys say things like,
"You don't have to set dwell time EVER, just set the points gap and run it..."
With absolutely NO CONCEPT of what Dwell Time does for the spark energy,
Or,
"Open your plug gap up to 0.050" or 0.060" of an inch, it will run better..."
So, now they are completely ignoring the time the coil has to saturate and driving up the demand for VOLTAGE to jump the plug gap,
And they give ZERO thought to anything else...
No Amperage in the spark at the plug, No duration of the spark at the plug gap, just drive voltage up and don't pay any attention to the ACTUAL FUNCTION of the ignition system...
I know I'm dealing with a shinning example of the public school system and a first rate communicator of 'Old Wives Tails'...
At least I know who I'm dealing with!
----------------------------------------------------------
You know I STRESS things like good, LOW IMPEDANCE plug wires,
(MSD spiral core LOW IMPEDANCE, LOW RESISTANCE wires)
Brass terminal caps, rotors with brass noses,
Common copper core plugs.
And there are reasons for all that, and they go well beyond what is available off the shelf...
And the guy wanting his vehicle to start on damp/cold mornings isn't going to do, or even understand any of this...
He just wants to know what to use that WORKS WELL and doesn't cost an arm/leg, couple of toes off the other foot...
The guy with a breaker point ignition that has some wear,
Or the distributor/breaker points set he has weren't exactly PERFECTLY made to factory specifications...
So I recommend a dwell meter to get things working like they should...
And the 'Experts' that had a running engine ONE TIME in the past rip into me from all directions!
>
Ignition Basics... Apples To Apples Approach
