Redressing a controversial subject...

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Brooks James

Brooks James

VET, CPT, Huey Medevac Pilot
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I had previously posted that I was was for the purposes of experimentation and fun , I would figure a way to attach 2 or 3 ignition coils in series to emit simultaneously occuring sparks, that would be joined together in 1 wire to the distributor cap.
My question is, would all the extra volts scramble everything inside the cap ???
 
Brooks James said:
I had previously posted that I was was for the purposes of experimentation and fun , I would figure a way to attach 2 or 3 ignition coils in series to emit simultaneously occuring sparks, that would be joined together in 1 wire to the distributor cap.
My question is, would all the extra volts scramble everything inside the cap ???
Click to expand...

A couple issues I see... the coil is designed for 30kV or so break down between the primary and secondary winding. Once you put them in series the negative of the next one in line will be at 30kV with its output at 60kV (with respect to ground). The primary needs to be switched from a floating driver that is not referenced to ground so that is design challenge number one. Next with 60kV - 90kV there is a good chance that the distributor would arc over internally as easy it jumps the gap. Lastly once the spark plug fires it will drop to the breakdown voltage of air across a gap and be pinned at much lower voltage than even the 1 coil puts out peak.. it only really makes this voltage for the time it take to ionize the air in plug gap. What value are you thinking this will give you?
 
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Brooks James said:
I had previously posted that I was was for the purposes of experimentation and fun , I would figure a way to attach 2 or 3 ignition coils in series to emit simultaneously occuring sparks, that would be joined together in 1 wire to the distributor cap.
My question is, would all the extra volts scramble everything inside the cap ???
Click to expand...
Oh I don't know. If it would work and be a benefit, someone would have tried it by now.
 
The top is what i belive you are suggesting. That would require 24v and would leak current to ground through the secondary which would destroy the coil

Bottom is in parallel which would double your current output but there would be no reason to go about it


1705021391260.jpeg
 
Jim Kueneman said:
A couple issues I see... the coil is designed for 30kV or so break down between the primary and secondary winding. Once you put them in series the negative of the next one in line will be at 30kV with its output at 60kV (with respect to ground). The primary needs to be switched from a floating driver that is not referenced to ground so that is design challenge number one. Next with 60kV - 90kV there is a good chance that the distributor would arc over internally as easy it jumps the gap. Lastly once the spark plug fires it will drop to the breakdown voltage of air across a gap and be pinned at much lower voltage than even the 1 coil puts out peak.. it only really makes this voltage for the time it take to ionize the air in plug gap. What value are you thinking this will give you?
Click to expand...
15 seconds of a huge spark plug fire, to be used in conjunction with nitrous only
 
Jim Kueneman said:
Once you put them in series the negative of the next one in line will be at 30kV with its output at 60kV (with respect to ground)
Click to expand...
If the potential difference of the primary terminals is 30kV the coil will instantly be destroyed. It is basically a short circuit with some inductance.
 
i was intrigued when i saw a diagram of a new plug by Toyota ?? that had two seperate electrodes, side by side, I thought, "thats going to take a shitton of voltage to do both electrodes at once"

it made me think of the dual plug hemi plug heads of yesteryear, 16 plugs and 2 magnetos
 
V=IR.

If you have two plugs in parallel all that means is that the output impedance is halved. If the source can provide the current, the voltage is irrelevant
 
remytherat said:
If the potential difference of the primary terminals is 30kV the coil will instantly be destroyed. It is basically a short circuit with some inductance.
Click to expand...

I am not implying the 30kV voltage is across the primary, you have to create a way to generate the correct voltage across the primary that is _not_ referenced to chassis ground and that return needs to be floated to 30kV. I don't think that a coil can take that as the case would also be floating at 30kV and all sorts of arc points need to be addressed (internal to the coil between the windings and the case as well).

If a coil was a 4 terminal device with separate ground terminals for the primary and secondary AND there was enough standoff between primary and secondary to withstand 60kV/90kV then the primary driver could be referenced to chassis ground on all the coils and driving the primary would be much simpler.
 
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remytherat said:
The top is what i belive you are suggesting. That would require 24v and would leak current to ground through the secondary which would destroy the coil

Bottom is in parallel which would double your current output but there would be no reason to go about it


View attachment 1716190909
Click to expand...

The way you have drawn these it is more of a current doubler (except the first I don't think that works as drawn). I am thinking more in terms of a voltage doubler/tripler from the OPs description.
 
Just put a Tesla (not the car company) coil in place of the automotive coil.

Also I'm not sure 2 coils in series would fire at the same time.
 
Why don’t you buy a msd multispark box and an accell coil and stop trying to reinvent the wheel.
 
Jim Kueneman said:
If a coil was a 4 terminal device with separate ground terminals for the primary and secondary AND there was enough standoff between primary and secondary to withstand 60kV/90kV then the primary driver could be referenced to chassis ground on all the coils and driving the primary would be much simpler.
Click to expand...
Yep, the biggest issue is the fact that if the ground of the primary is floating then so is the ground of the secondary.

Wait till the op finds that magnetos exist and big sparks fly out of them!!!
 
Edit
Just found a 60k volt racing coil at Summit for $30 bucks that I'll use with my MSD 6 Al, that'll get it till
I can cobble something together
Would love a mag but too $$$
Joe Hunt Vertex Magneto $1450
 
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You might be a able to make an early hemi mag work on a small block...they are out there...
 
Have a bank of condensers, each timed to fire consecutively, 1 coil, x# condensers, spark lasts a full revolution.
 
remytherat said:
You might be a able to make an early hemi mag work on a small block...they are out there...
Click to expand...
that would be lovely and keeping with the the theme of my 70 Dart that has vintage correct speed pieces on the engine
holley carb, factory dual snorkle cleaner, I know chinesium air gap intake not era correct, intakes for magnum severely limited
crane fire ball cam 498/274 intake 512/286 exhaust, 113 lsa, Accell coil, etc
 
60KV coil??

What does that mean?

it doesn't mean 60KV spark
Because the voltage that jumps the gap can be as low as 6 KV with no fuel and low Compression
and 12-25 KV with compressed fuel and air in the gap
so if it fires at 25KV it will fire at 25 KV
if the plug fires at 30 it fires at 30
you'd have to open the gap up to something silly to get it to be 60 KV with a moderately sensible combination of CR and Fuel just not going to happen on a car that is streetable using a normal ignition set up
you might get 60 KV if you spike it with a CDI but again the KV level the spark is produced at is dictated by how hard tha gap is to jump and with all else the same it will still be 25 or 30 KV

makes no odds what it says on the coil

so that 60KV rateing is one of 2 things

1) the maximum voltage it can withstand without shorting out inside
2) the maximum voltage they managed to achieve using that coil and a huge gap at the plug that you would never run in a car engine.

CDI---very high voltage low current into primary can produce very very high voltage low current out of the secondary if you conspire to make the gap that needs to be jumped very large

in general though rateing a coil by KV is marketing rubbish
rate a coil by turns ratio
rate a coil by primary and secondary resistance
Rate a coil by saying perfect for use in a capacitive discharge igntion....

rating a coil by the effectiveness of the insulation used in its manufacture says nothing about performance its about as much use as saying this coil is RED this coil has a sticker with a lightning bolt on it


2 coils in series
one end sees 12-14 volts the other end sees 0 volts both coils then run on 6-7 volts if they are exactly the same type.
you have doubled the resistance in the circuit so you have reduced the current flow by half.
if it was 3 amps its now 1.5 if it was 6 its now 3
current flow dictates how fast the field grows to maximum. lower current flow means slower growing and smaller magnetic field
producing a not very impressive spark from each
if they are not the same type the voltage will be distributed across them in the same ratio as their primary resistance.

2 coils in parallel
you consume double the current when they are ON
current is usually limited by the coil primary resistance or the ballast or both
its limited so that you don't
1) burn out the points
2) burn out the blue box orange box chrome box etc
3) overload the wires

if the max current was 6 amps each coil will now try to allow 6 amps to flow
if the limit to this is external to the coil they won't flow the 6 amps they expect to flow
the magnetic field they create will take longer to grow to maximum
you kinda doubled the dwell you need to create a good spark
or reduced the operating rpm range by approximately 1/2.

if the switch (module/box or points) can flow 12 amps both coils will work as intended but marrying up the secondary output is not necessarily going to work. unless everything is totally identical.
and i wouldn't try it with my tacho connected.

better to get 1 single coil with a different primary resistance... lower
a switch (module or box) that can put up with flowing a current in the 6 - 8 amp range
and a ratio that produces a higher voltage spark
usually indicated by the coil manufacturer suggesting slightly wider plug gaps

HEI coil
low primary resistance 0.6 ohm designed to run at 14 volts and a suggestion of 40 or 45 thou gap at the plugs

Mopar coil low primary resistance 0.6 ohms designed to run at 8-9 volts with a plug gap of 30 or 35 thou

lower primary resistance means shorter necessary dwell to get to the magnetic field up to decent level hence improved RPM range

doubling up coils in parallel gives the impression of lower primary resistance
but that isn't the case both coils have the same primary resistance they always had
just the current has two routes to follow rather than 1

No real gain
if you want more than 1 coil look up wasted spark ignition you could fit a megajolt and use a Ford EDIS coil pack or 2 off a v8 or 2 I4 fords

Dave
 
Dave999 said:
60KV coil??

What does that mean?

it doesn't mean 60KV spark
Because the voltage that jumps the gap can be as low as 6 KV with no fuel and low Compression
and 12-25 KV with compressed fuel and air in the gap
so if it fires at 25KV it will fire at 25 KV
if the plug fires at 30 it fires at 30
you'd have to open the gap up to something silly to get it to be 60 KV with a moderately sensible combination of CR and Fuel just not going to happen on a car that is streetable using a normal ignition set up
you might get 60 KV if you spike it with a CDI but again the KV level the spark is produced at is dictated by how hard tha gap is to jump and with all else the same it will still be 25 or 30 KV

makes no odds what it says on the coil

so that 60KV rateing is one of 2 things

1) the maximum voltage it can withstand without shorting out inside
2) the maximum voltage they managed to achieve using that coil and a huge gap at the plug that you would never run in a car engine.

CDI---very high voltage low current into primary can produce very very high voltage low current out of the secondary if you conspire to make the gap that needs to be jumped very large

in general though rateing a coil by KV is marketing rubbish
rate a coil by turns ratio
rate a coil by primary and secondary resistance
Rate a coil by saying perfect for use in a capacitive discharge igntion....

rating a coil by the effectiveness of the insulation used in its manufacture says nothing about performance its about as much use as saying this coil is RED this coil has a sticker with a lightning bolt on it


2 coils in series
one end sees 12-14 volts the other end sees 0 volts both coils then run on 6-7 volts if they are exactly the same type.
you have doubled the resistance in the circuit so you have reduced the current flow by half.
if it was 3 amps its now 1.5 if it was 6 its now 3
current flow dictates how fast the field grows to maximum. lower current flow means slower growing and smaller magnetic field
producing a not very impressive spark from each
if they are not the same type the voltage will be distributed across them in the same ratio as their primary resistance.

2 coils in parallel
you consume double the current when they are ON
current is usually limited by the coil primary resistance or the ballast or both
its limited so that you don't
1) burn out the points
2) burn out the blue box orange box chrome box etc
3) overload the wires

if the max current was 6 amps each coil will now try to allow 6 amps to flow
if the limit to this is external to the coil they won't flow the 6 amps they expect to flow
the magnetic field they create will take longer to grow to maximum
you kinda doubled the dwell you need to create a good spark
or reduced the operating rpm range by approximately 1/2.

if the switch (module/box or points) can flow 12 amps both coils will work as intended but marrying up the secondary output is not necessarily going to work. unless everything is totally identical.
and i wouldn't try it with my tacho connected.

better to get 1 single coil with a different primary resistance... lower
a switch (module or box) that can put up with flowing a current in the 6 - 8 amp range
and a ratio that produces a higher voltage spark
usually indicated by the coil manufacturer suggesting slightly wider plug gaps

HEI coil
low primary resistance 0.6 ohm designed to run at 14 volts and a suggestion of 40 or 45 thou gap at the plugs

Mopar coil low primary resistance 0.6 ohms designed to run at 8-9 volts with a plug gap of 30 or 35 thou

lower primary resistance means shorter necessary dwell to get to the magnetic field up to decent level hence improved RPM range

doubling up coils in parallel gives the impression of lower primary resistance
but that isn't the case both coils have the same primary resistance they always had
just the current has two routes to follow rather than 1

No real gain
if you want more than 1 coil look up wasted spark ignition you could fit a megajolt and use a Ford EDIS coil pack or 2 off a v8 or 2 I4 fords

Dave
Click to expand...
Yep. 60 KV is maximum output. A .035 gap can be jumped with a flywheel off a Briggs and Stratton. :lol:
 
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