Topic: Dynatek leads and stock plug caps

[PeWe]

I was also told  many years ago that resistor in plug/ cap was for reducing EMI/RFI,  not send disturbing radio waves. Today important to not disturb the own electronics for engine control, ignition.

[Deltarider]

I was also told  many years ago that resistor in plug/ cap was for reducing EMI/RFI,  not send disturbing radio waves. Today important to not disturb the own electronics for engine control, ignition.

That's what they're for, first and for all. In the automotive literature I have, there's no mentioning of duration benefits. Not that they cannot occur but I doubt they're significant. Therefor I would like to see proof like oscilloscope images.

[garyS-NJ]

I believe hondaman knows these bikes and so spark duration might not be academic.   But maybe I'm over thinking some of this due to electronics background.   I was thinking about back emf and how high freq components might affect the overall current flow during discharge...  But this just says use a resistor plug if you want to avoid noise and don't use carbon-glass wires.. http://www.motorcycleproject.com/text/plugwiretech.html

Sent from my VS987 using Tapatalk

[HondaMan]

I was also told  many years ago that resistor in plug/ cap was for reducing EMI/RFI,  not send disturbing radio waves. Today important to not disturb the own electronics for engine control, ignition.

It does, PeWe: the same principle that causes the resistance to stretch out the pulse duration also reduces the "rise time" of the spark energy. This reduces the spurious oscillations that occur as the magnetic field rapidly collapses (rather willy-nilly, based on the accuracy of the windings in the coil body). These oscillations are known as "sideband radiation" in the radio-design trade, and they can reach all the way up to many megahertz in frequency. These are the "static" noises that you hear in, for example, your car's radio if you tune in-between stations with the engine running: as you rev the engine, you can hear it as the static noise in the radio changes. The resistance forces the coil's field to collapse more slowly, which both reduces these random oscillations' amplitude (i.e., signal strength) and reduces their frequency to a lower value, hopefully below that of the station you are trying to listen to at the time.

(Yep...I also have a First-Class FCC Radio-Telephone license, and over the years have designed quite a few transmitters and receivers...)

[PeWe]

Thanks to this forum where Hondaman and other very exeprienced guys share their knowledege, we know that there are more about the reistance than we ever known before
I'll see more coming season wheen I need to get plugs with perfect color, no pingning and good A/F ratio that I'll measure while driving.

[garyS-NJ]

I think hondaman above ment to increase the rise time or slow the rate of change.  This would logically reduce overshoot and the sharp high freq edges which radiate energy.. Decrease emi.  From my electronics and physics experience I felt that series resistance might act to reduce the pulse magnitude and stretch out the pulse but I think poking around the other day I only found stuff saying resistance reduces the magnitude but not appreciably...

Sent from my VS987 using Tapatalk

[HondaMan]

I think hondaman above ment to increase the rise time or slow the rate of change.  This would logically reduce overshoot and the sharp high freq edges which radiate energy.. Decrease emi.  From my electronics and physics experience I felt that series resistance might act to reduce the pulse magnitude and stretch out the pulse but I think poking around the other day I only found stuff saying resistance reduces the magnitude but not appreciably...

Sent from my VS987 using Tapatalk

The coils are an "R-L" circuit, tuned with a capacitance (the condensor) to a low "Q" (resonance) value. This L-R-C circuit oscillates at frequencies up to 1.5MHz during discharge, if left to its own devices, and the long wires between the points and coil make good transmitters, as they have almost no resistance. Adding resistance to the discharge side causes the magnetic field's collapse to slow down a little bit, dropping the upper frequency to less than 150KHz, well below the AM radio band. Since this stores energy (natural conservation) it also makes the spark last longer (as outlined in my book).

..for those who care to follow it, from the FCC's First Class Radiotelephone manual...  

[Deltarider]

Since this stores energy (natural conservation) it also makes the spark last longer (as outlined in my book).

..for those who care to follow it, from the FCC's First Class Radiotelephone manual...  

I do, hence my question: is a longer spark duration stated in that FCC's First Class Radiotelephone manual? Anywhere?
What so far has been left left out of the equation, is the heating of the resistors. Little as that may be, my idea of natural conservation of energy tells me it must be there.
But I'm eager to learn. If there's a significant longer spark duration, oscilloscope screens will show.

[garyS-NJ]

Fcc isn't thinking about spark duration and seems there is little to find on this. I read somewhere that the condenser acts to tune the primary circuit but I think that really means to shunt down the high freq spike thereby protecting your points.  As the condenser goes bad the points arc like crazy.  The condenser cap is initially a short to high freq so when the points open, the primary winding continues the current producing a spike voltage (up to 300 volts?).  The condenser will make for some ringing out (longer duration primary) but i think lower the peak voltage across the points.  Now Idk if that primary ringing will effectively ring the secondary for a longer spark.. MSD ignitions use multiple sparks to spread the spark duration. Resistance in the secondary path may well play into an LC circuit formed by the secondary coil and the spark plug itself acting like a small capacitor but again I haven't found much on this (I bet Delco has some material out there).  I think more so it limits the secondary voltage rise time which effectively is eliminating high freq components which would radiate and not lend anything to firing your mixture. For sure tho, resistance in the secondary should be no more than a practical amount which does reduce the voltage available to jump the spark gap.

Sent from my VS987 using Tapatalk

[garyS-NJ]

And heating resistors does increase their resistance but its only a few percent and I don't think that is an issue here..  Lets remember this thread started with using the Dyna plug caps or ngk.  My bet is they are both 5k made by comparable sources.  But then a better question stands is should we all be using resistor plugs for a longer spark duration or do we want to open plug gaps for a higher secondary voltage??  I read somewhere that wider plug gaps with higher voltage would perhaps make a better flame for a while but then tend to wear out the spark plugs faster.. (Like running 55w hid lights instead of 35w).  Note that as plugs wear, the gap gets bigger and the gap length limits the voltage across the gap (smaller gap, smaller secondary voltage). But as the gap increases, its good to have available secondary voltage to jump that gap.  So should we all run resistor plugs for longer spark or just to be nice with spurious emi??

Sent from my VS987 using Tapatalk

[Deltarider]

And heating resistors does increase their resistance but its only a few percent and I don't think that is an issue here..

What I said is not referring to resistors increasing their resistance by heating. That's futile, we can agree on that. What I meant is all resistors by their nature become warmer when there's current going through them, indicating they consume energy, it's as simple as that. Hence my statement: little as that may be, my idea of natural conservation of energy tells me that is were the energy goes: up in joules in the resistors.
I have found no confirmation for the hypothesis that resistors give a longer spark duration, not even in NGK's documents, let alone in my handbooks. Again, I'm eager to learn and if there's a significant longer spark duration, no doubt oscilloscope screens will show us. But for the time being all this is academic hairsplitting IMO. What I can understand, is that there's less oscillating as the resistors act both ways.
The condensor is another story. It's to prevent arcing between the points that switch around 3A which is a lot. A benificial side effect is the up to 300V induction in the primary that helps the coil to perform well.

[kmb69]

Mark may actually be right, this time. 

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

[Deltarider]

Mark may actually be right, this time. 

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

Can you be a little more specific where?

[kmb69]

Mark may actually be right, this time. 

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

Can you be a little more specific where?

If I am understanding the linked article, it appears that resistance on the secondary effects spark duration. Am I reading/understanding that incorrectly?

[seanbarney41]

That's what I got from it

[jonda500]

But, according to that article a "high secondary resistance" causes a short "Spark Burn Time Duration", not long??
John

[kmb69]

But, according to that article a "high secondary resistance" causes a short "Spark Burn Time Duration", not long??
John

I think you are correct. From that standpoint, Mark got it bass ackwards. 

But secondary resistance, whether low or high, does apparently effect spark duration answering Deltarider's and garyS-NJ's questions.

[Deltarider]

But secondary resistance, whether low or high, does apparently effect spark duration answering Deltarider's and garyS-NJ's questions.

So far I've seen no proof of that, just claims.

[kmb69]

I am not an Electrical Engineer for sure. Can only go by what I read. Found this article published by Snapon related to equipment they sell. If I'm reading this one correctly, it indicates that resistance lowers the secondary voltage increasing burn time. Also mentions our wasted spark system at the end of the article.

[kmb69]

So far I've seen no proof of that, just claims.

Agreed. I cannot find any irrefutable, empirical evidence or proof.

[PeWe]

Mark has constructed his own well working ignition module and has decades of practical experience from the very beginning of the CB750 era. I have got it right or even better by reading and follow his hints how to do/how it works. I guess there are something more with resistance too.

[MRieck]

 I use Taylor Spiro-Pro and MSD Super Conductor wires with Dyna 2000 ignitions. No problems with either brand

[Don R]

 Just a side note, early in the cold war, seeking RF noise was considered a viable method to find a large city with a ballistic missile. Also, my brothers 55 chevy with solid core wires and rajah plug terminals would roll the picture on our VHF antenna TV from 3 blocks away.

[MRieck]

Just a side note, early in the cold war, seeking RF noise was considered a viable method to find a large city with a ballistic missile. Also, my brothers 55 chevy with solid core wires and rajah plug terminals would roll the picture on our VHF antenna TV from 3 blocks away.

You should see what it does to a computer used with a dyno.

[HondaMan]

Since this stores energy (natural conservation) it also makes the spark last longer (as outlined in my book).

..for those who care to follow it, from the FCC's First Class Radiotelephone manual...  

I do, hence my question: is a longer spark duration stated in that FCC's First Class Radiotelephone manual? Anywhere?
What so far has been left left out of the equation, is the heating of the resistors. Little as that may be, my idea of natural conservation of energy tells me it must be there.
But I'm eager to learn. If there's a significant longer spark duration, oscilloscope screens will show.

Yep, the FCC First Class training (antennas) section outlines how adding resistance to a high-Q antenna system will reduce the EMI sideband radiations while simultaneously increasing the power at the desired frequency. While the resistors will heat (that's what they are made to do!), this loss is miniscule in comparison to the energy being dissipated in the tank circuit, which in a Kettering system is the Spark. In the case of the OEM coils, this loss is less than 1.2% of the total spark energy. If the Dyna 3-ohm coils are used it becomes about 2.3%.

When I developed the Transistor Ignition here, I posted pictures of the oscilloscope waveforms involved, just for this purpose. I showed them with and without resistive caps: the OEM coils used the 5k ohm NGK caps and the Dyna 3 ohm coils used the resistor wires (800 ohms) supplied by Dyna, with copper caps. The discharge was very short and hot (high amplitude) with the Dyna setup, around 0.9mS duration, while the OEM setup was closer to 1.4mS. In the waveforms, you can see the spurious frequencies banging all over in the Dyna coils: when I later added the 5k caps to the Dynas with copper wires instead, the spurious radiation was much reduced in the waveforms and the duration was longer, about 1.1mS. We might still be able to dig up those threads: there are 4 of them in total.