Show me a pic of the Jag set up if you can.
If it was a modified coil, with a second primary inside the coil housing, sharing a common core with the existing primary and secondary then yes, there will be some advantage.
Just running a second coil setup will do absolutely nothing.
I will call MONSTER CABLE THEORY on this one.
MONSTER CABLE THEORY.
If you use monster cable for your speaker cables you will get better sound.
My theory is 2 people believe this.
The salesman selling the stuff.
The fool who paid for the stuff.
My Tip - Twin coils easy as 1-2-3
Started by
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, Feb 28 2009 06:41 AM
90 replies to this topic
#26
Rockoz
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Posted 28 February 2009 - 11:12 PM
#27
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Posted 28 February 2009 - 11:40 PM
It works because the switched current through the transistor can rise faster with two coils in parallel connected to the circuit, I'll keep out of equations but it does make sense. but I can only see it being useful when the time between firing pulses gets short enough to stop coil saturation occuring. Its the same affect you can get with points by closing the gap down that is dwell is extended. (albeit using a different approach).
The Monster cable thing is a whole subject in itself. Did you know you can get special XXXXXX cable power leads too. And they make a difference! Never mind the miles of crappy oxegenated copper, aluminium, steel and other metals between you and the generator, Buy monster power cables and the sound is better only $US 950 per cable.
Check the WWW. Buy now! they need the money to overcome the financial crisis. (they reckon its not a scam I reckon it is) (manufacturers name hidden for legal reasons)
Good theory yours Rockoz
The Monster cable thing is a whole subject in itself. Did you know you can get special XXXXXX cable power leads too. And they make a difference! Never mind the miles of crappy oxegenated copper, aluminium, steel and other metals between you and the generator, Buy monster power cables and the sound is better only $US 950 per cable.
Check the WWW. Buy now! they need the money to overcome the financial crisis. (they reckon its not a scam I reckon it is) (manufacturers name hidden for legal reasons)
Good theory yours Rockoz
#28
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Posted 01 March 2009 - 12:16 AM
my thoughts are the extra coil will reduce the saturation time as the circuit is now trying to charge 2 coils, not one, using the same voltage (pressure).
the current, being (flow) is directly propertional to the load (resistance) and voltage applied.
putting the 2 in parallel will be seen as less resistace to the transistor,but the only thing that has really changed is the system now has to deliver twice the current in the same time. this will pull the voltage down slowing the charge time.
If you say it works there must be a reason, all I can think of is the second coil allows the first coil to discharge faster as they become a series circuit once the power is removed. this creating a shorter, larger spark.
if this is the case a large diode across the coil may work?
maybe some other reason?
the current, being (flow) is directly propertional to the load (resistance) and voltage applied.
putting the 2 in parallel will be seen as less resistace to the transistor,but the only thing that has really changed is the system now has to deliver twice the current in the same time. this will pull the voltage down slowing the charge time.
If you say it works there must be a reason, all I can think of is the second coil allows the first coil to discharge faster as they become a series circuit once the power is removed. this creating a shorter, larger spark.
if this is the case a large diode across the coil may work?
maybe some other reason?
#29
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Posted 01 March 2009 - 12:40 AM
Been a long time since I studied electronics engineering.
Has someone misinterpreted the idea Jag had somewhere along the line?
Has the equivalent of an Urban myth been created?
Is the so called Dummy Coil on the Jag a seperate unit, or another coil wound with the operating coil?
I think that maybe a parallel resistor may have achieved the same result.
A second coil would more than likely need a change in capacitor if using points.
There would be issues with the energy produced by the second coil with no load.
A diode across the coil would either short the applied power, or the induced power depending on which way it was connected.
Either would be detrimental to spark production
Would love to see the theory behind it.
If I get a chance I will try it on a dyno.
Got access to one of them occasionally.
Has someone misinterpreted the idea Jag had somewhere along the line?
Has the equivalent of an Urban myth been created?
Is the so called Dummy Coil on the Jag a seperate unit, or another coil wound with the operating coil?
I think that maybe a parallel resistor may have achieved the same result.
A second coil would more than likely need a change in capacitor if using points.
There would be issues with the energy produced by the second coil with no load.
A diode across the coil would either short the applied power, or the induced power depending on which way it was connected.
Either would be detrimental to spark production
Would love to see the theory behind it.
If I get a chance I will try it on a dyno.
Got access to one of them occasionally.
#30
_NZ Toranaman_
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Posted 01 March 2009 - 06:17 AM
A coil is a transformer that boosts 12v to around 40,000v in 2 stages
The 12v is passed through the primary winding of say 600 coils of fine copper wire which raises the voltage.
The dizzy when it is time to fire causes the collapse of the primary winding.
This causes a surge of electricity to the secondary winding which has even more windings of even finer wire(enough to stretch the 1/4 mile 3 or 4 times) it is this that causes the multiplying of the voltage to become around 40,000v
Here is my interpretation of what I was told.
The second coil speeds up the primary process, it doesn't alter the voltage to the secondary in the main coil, thus it makes sure you can get your optimum 40,000 at higher revs which lets face it thats where all motors make the real power. On the test I saw it was on a V8 of respectable power and made an extra 6hp from mid-range to top end over a single stock coil.
I never wanted to compare this against an MSD as MSD is always going to be better as everyone knows what MSD means? Multi Spark Discharge and that way your can have say 2-6 sparks instead of one which causes cleaner burn.
This was only a tip I was given that never seems to be mentioned much and I used at the speedway on an engine that had be stock... the extra coil could be hidden anywhere and as I always had a few spares in this area thrown under a bench it is zero cost to me and even if it got me an extra 4hp it is still extra that I would not have had as MSD is out of reach for my budget.
BTW my little LC takes a second in budget to my family as I have 1 Grandaughter and another 3 on the way by July.
If someone who has access to a dyno could do a test it would be mighty as I am keen to see this repeated and if it turns out correct then you saw it first on GMH-Torana forum
If it turns out the other way which I dont think it will hey I live and learn again.
The 12v is passed through the primary winding of say 600 coils of fine copper wire which raises the voltage.
The dizzy when it is time to fire causes the collapse of the primary winding.
This causes a surge of electricity to the secondary winding which has even more windings of even finer wire(enough to stretch the 1/4 mile 3 or 4 times) it is this that causes the multiplying of the voltage to become around 40,000v
Here is my interpretation of what I was told.
The second coil speeds up the primary process, it doesn't alter the voltage to the secondary in the main coil, thus it makes sure you can get your optimum 40,000 at higher revs which lets face it thats where all motors make the real power. On the test I saw it was on a V8 of respectable power and made an extra 6hp from mid-range to top end over a single stock coil.
I never wanted to compare this against an MSD as MSD is always going to be better as everyone knows what MSD means? Multi Spark Discharge and that way your can have say 2-6 sparks instead of one which causes cleaner burn.
This was only a tip I was given that never seems to be mentioned much and I used at the speedway on an engine that had be stock... the extra coil could be hidden anywhere and as I always had a few spares in this area thrown under a bench it is zero cost to me and even if it got me an extra 4hp it is still extra that I would not have had as MSD is out of reach for my budget.
BTW my little LC takes a second in budget to my family as I have 1 Grandaughter and another 3 on the way by July.
If someone who has access to a dyno could do a test it would be mighty as I am keen to see this repeated and if it turns out correct then you saw it first on GMH-Torana forum
If it turns out the other way which I dont think it will hey I live and learn again.
#31
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Posted 01 March 2009 - 08:48 AM
The theory behind this seems to me to be to decrease the inductance of the ignition coil apparent to the circuit.
Inductors oppose current change so when the circuit first switches on the full potential of the supply appears across the coil as it seems to be an open circuit.
As charge builds up the apparent resistance of the coil reduces until at saturation it is at its DC resistance.
If you put a resistor across the coil it does not reduce the inductance and instead acts as a voltage divider with all the other series resistance in the circuit so you wont see the full supply across the coil thus its actually detrimental to the system.
placing a parallel coil on the same magnetic circuit does not change the inductance at all it just appears as a lower DC resistance . winding more turns onto the primary will increase the inductace and slow down the current rise time.
Placing another similar inductor completely seperate to the original reduces the inductance in the circuit and the risetime of the system is faster therby increasing the apparent dwell time.
There will be issues produced with a second coil as I have already noted.
With a points system this will work but will be awful hard on the points as they will need to carry twice their rated current. If you changed the capacitor to accomadate the lower inductance you would need twice the capacitance to get back to the same fundemental sytem frequency which would put you back to the status quo.
Hope this is adequate explanation for all, as I said originally I was suss but once pointed to the Jag page and doing some research it does make some sense. However i reiterate I personally would not do it to a road car as I see the issues caused as being too great. Might go with it for racing if I was at WOT a lot of the time as the issues would probably not become a serious problem in the time it takes for most races.
Inductors oppose current change so when the circuit first switches on the full potential of the supply appears across the coil as it seems to be an open circuit.
As charge builds up the apparent resistance of the coil reduces until at saturation it is at its DC resistance.
If you put a resistor across the coil it does not reduce the inductance and instead acts as a voltage divider with all the other series resistance in the circuit so you wont see the full supply across the coil thus its actually detrimental to the system.
placing a parallel coil on the same magnetic circuit does not change the inductance at all it just appears as a lower DC resistance . winding more turns onto the primary will increase the inductace and slow down the current rise time.
Placing another similar inductor completely seperate to the original reduces the inductance in the circuit and the risetime of the system is faster therby increasing the apparent dwell time.
There will be issues produced with a second coil as I have already noted.
With a points system this will work but will be awful hard on the points as they will need to carry twice their rated current. If you changed the capacitor to accomadate the lower inductance you would need twice the capacitance to get back to the same fundemental sytem frequency which would put you back to the status quo.
Hope this is adequate explanation for all, as I said originally I was suss but once pointed to the Jag page and doing some research it does make some sense. However i reiterate I personally would not do it to a road car as I see the issues caused as being too great. Might go with it for racing if I was at WOT a lot of the time as the issues would probably not become a serious problem in the time it takes for most races.
#32
rodomo
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Posted 01 March 2009 - 09:58 AM
Show me a pic of the Jag set up if you can.
I dont think you'll find one as apparently this set-up was hidden somewhere behind the grill.
More stuff:
"The original parallel coil arrangement was "conceived when coils of sufficiently low resistance were not available."
"Jaguar now recommends replacing both coils with a single "solid" (not oil filled) coil (#DAC 6093, Ducelier coil - 0.62 ohms primary) that fits in place of the main coil."
#33
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Posted 01 March 2009 - 10:38 AM
I knew i still had the old article somewhere so I delved into my box of my old trade books and bugger me i kept it...Its an article by Rick O'Toole for Street Heat...pretty sure i can't scan it for copyright reasons but if a mod gives me the nod I'll do it.
The gist of the article is that the mod was done on a car belonging to James Goldmine, the car was an ex Colin Bond Falcon with a 351 that had Motec M48 injection, Roush manifolds etc etc.
Originally it had a Bosch MEC-718 coil on it and they twinned it up with another MEC-718. The result was a solid 6 HP gain almost completely across the rev range...so the dyno testing has been done.
I can see the limitations and I'm not saying its better than HEI....all I said was that it works well..and it does
The gist of the article is that the mod was done on a car belonging to James Goldmine, the car was an ex Colin Bond Falcon with a 351 that had Motec M48 injection, Roush manifolds etc etc.
Originally it had a Bosch MEC-718 coil on it and they twinned it up with another MEC-718. The result was a solid 6 HP gain almost completely across the rev range...so the dyno testing has been done.
I can see the limitations and I'm not saying its better than HEI....all I said was that it works well..and it does
Edited by FastEHHolden, 01 March 2009 - 10:41 AM.
#34
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Posted 01 March 2009 - 12:07 PM
Many years ago I was toying with the idea of two complete ignition systems in parallel ie. two ignition modules (CDI's back then) sharing a common trigger that fired two separate coils. The idea was to have the secondary output of each coil connected in parallel and to the centre of the dissy cap as normal. Before I started though, I wanted to run a test to see what influence each coil would have on the other, and in particular to see whether one system going dead would bring the other one down too. So I grabbed a coil (just a normal 12v resistor coil) and ran a wire from the output post to the output of the existing coil and left the other terminals disconnected. This was on an injected Volvo engine with points ignition (don't ask...) The engine started straight away and seemed to be idling faster and smoother than normal. So I pulled the wire (gingerly) from the extra coil as it was running and the idle retuned to normal; reconnecting the wire increased the idle speed very perceptively (by about 100rpm) and also perceptively smoothed the idle. I never really understood how this "free floating" second coil could alter the spark, and the ignition project was never pursued further, being placed on the "things-to-look-into-when-time-permits" list. At any rate for a definitive answer an oscilloscope test would soon show whether any of these 2nd coil setups are doing anything worthwhile, so if anyone has the time and gear available I'd love to see the findings. BTW I also played briefly with diodes and resistors across the primary winding of points systems and never found any worthwhile gains.
#35
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Posted 01 March 2009 - 01:57 PM
Thanks FastEHHolden...
I was starting to think I dreamed it one night but that sounds like the same info I had...
I was starting to think I dreamed it one night but that sounds like the same info I had...
#36
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Posted 01 March 2009 - 11:07 PM
Out of curiosity would there be any benefit running twin coils on an HEI system?
#37
rodomo
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Posted 01 March 2009 - 11:24 PM
"The original parallel coil arrangement was "conceived when coils of sufficiently low resistance were not available."
"Jaguar now recommends replacing both coils with a single "solid" (not oil filled) coil (#DAC 6093, Ducelier coil - 0.62 ohms primary) that fits in place of the main coil."
If you have a good read of this thread, you will learn that the original reason for this mod relates more to early V12 Jag engines in that when they are spinning at high RPM, a single coil struggles to cope. (not enough saturation/dwell time)
FastEH also relates an article regarding Ford V8 race engines.
Have a good read and you should work out that this mod. probably won't be too beneficial on your application being a six.
Others may post later as there is interest as to what effect this will have on dyno figures.
#38
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Posted 01 March 2009 - 11:41 PM
Well ill be stuffed then.
Will look into this further one day.
Still not too old to learn something new.
Gunna have to find the textbooks and dust em off.
Will look into this further one day.
Still not too old to learn something new.
Gunna have to find the textbooks and dust em off.
#39
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Posted 01 March 2009 - 11:53 PM
Well ill be stuffed then.
Don't be stuffed mate! You've got me stuffed in the tacho thread.
#40
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Posted 02 March 2009 - 01:35 AM
Placing another similar inductor completely seperate to the original reduces the inductance in the circuit and the risetime of the system is faster therby increasing the apparent dwell time.
There will be issues produced with a second coil as I have already noted.
With a points system this will work but will be awful hard on the points as they will need to carry twice their rated current.
Hope this is adequate explanation for all, as I said originally I was suss but once pointed to the Jag page and doing some research it does make some sense.
Having trouble understanding how this arrangement could work.
You are saying the benefit is achieved by the 1st coil current rising faster?
I understand how inductance in the combined paralled circuit of two coils is reduced and that the total current flowing through the combined circuit increases, but dont understand how this changes what is happening in the single firing coil. Wont the current going through it be doing exactly the same thing regardless of the other one? I can only think that there is something happeing on the discharge part of the cycle, that the two primary circuits effectively in a series closed circuit, together with the core connected secondary circuit of the non firing coil creating the effect.
The article quoted did mention that it was using perhaps standard coils of yesteryear, and that the process wasnt necessary with hei coils available today, so perhaps there is nothing to gain by wiring up two hei coils to a bosch electronic ignition, other than perhaps as already described challenging the ability of the dizzy module to switch the extra current to ground.
As aready mentioned it would be tougher on points, but woullnt work as suggested with the normal holden resistor wire setup, neither coil would recieve enough voltage with the resistor wire becoming an effectively larger chunk of resistance of the circuit. Two resistor wires in parallel would need to be run.
I do acknowledge the testimonials listed by several above and am keeping an open mind, but not convinced yet.
I have looked at the links to the jags, and there only seems to be one single description used by several articles, without any adequate explanation to how it works.
How could this mod be hidden from the rest of the automotive world for so long, particularly the racers back before the days of electronic systems, who would have all been struggling for enough spark with v8s doing 6000rpm+ with points systems and conventional coils.
#41
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Posted 02 March 2009 - 06:03 PM
Well I guess its formula time Torbirbie:
there is a formula for risetime in a circuit that says {t=L/R}
which translates as risetime equals inductance divided by resistance.
The ignition system is a practical circuit it has series resistance (from the wiring the module and the actual resistance of the inductor coil which is always considered as being in series with the coil). So although the resistanc of the coils is also in parallel halving the coil resistance there are other resistances in the circuit that can not be overcome. The transistors used in the old HEI were in the main what is known as Bipolar Junction transistors which have a (by comparison too todays Field Effect Transistors ) a reasonable resistance, wiring has some resistance you get the drift.
Thus halving the inductance whilst reducing the circuit resistance by less than half lowers the circuit rise time.
If it was a perfect world with no other resistances in the circuit it woudn't work but as we are in the real world it does.
As said at first I was with you but some research and a good deep think with the old dusty brain and it does make sense.
and yes you are correct with the resistance wire in the circuit its voltage drop would double and you would have to run another resistance direct from the switched battery suppply to the second coil.
there is a formula for risetime in a circuit that says {t=L/R}
which translates as risetime equals inductance divided by resistance.
The ignition system is a practical circuit it has series resistance (from the wiring the module and the actual resistance of the inductor coil which is always considered as being in series with the coil). So although the resistanc of the coils is also in parallel halving the coil resistance there are other resistances in the circuit that can not be overcome. The transistors used in the old HEI were in the main what is known as Bipolar Junction transistors which have a (by comparison too todays Field Effect Transistors ) a reasonable resistance, wiring has some resistance you get the drift.
Thus halving the inductance whilst reducing the circuit resistance by less than half lowers the circuit rise time.
If it was a perfect world with no other resistances in the circuit it woudn't work but as we are in the real world it does.
As said at first I was with you but some research and a good deep think with the old dusty brain and it does make sense.
and yes you are correct with the resistance wire in the circuit its voltage drop would double and you would have to run another resistance direct from the switched battery suppply to the second coil.
#42
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Posted 02 March 2009 - 06:51 PM
Well I guess its formula time Torbirbie:
there is a formula for risetime in a circuit that says {t=L/R}
which translates as risetime equals inductance divided by resistance.
The ignition system is a practical circuit it has series resistance (from the wiring the module and the actual resistance of the inductor coil which is always considered as being in series with the coil). So although the resistanc of the coils is also in parallel halving the coil resistance there are other resistances in the circuit that can not be overcome. The transistors used in the old HEI were in the main what is known as Bipolar Junction transistors which have a (by comparison too todays Field Effect Transistors ) a reasonable resistance, wiring has some resistance you get the drift.
Thus halving the inductance whilst reducing the circuit resistance by less than half lowers the circuit rise time.
If it was a perfect world with no other resistances in the circuit it woudn't work but as we are in the real world it does.
Thankyou for spending the time to attempt to clarify. Unfortuantely for me, none of that seems to make it any clearer at all. Perhaps you can not overcomplicate/camoflage it by leaving out the reference to transistor theory of the electronic ignition, this system worked(apparently) on points too .
Edited by torbirdie, 02 March 2009 - 06:58 PM.
#43
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Posted 02 March 2009 - 06:53 PM
double post
Edited by torbirdie, 02 March 2009 - 06:54 PM.
#44
VitcLJ
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Posted 02 March 2009 - 08:53 PM
My apologies TOP GEAR was on.
HEI, points Its all the same really, wires have resistance and you can't easily overcome it.
The thing about transistors was just that some people think they have no resistive losses and its not true especially of the older junction type devices.
It really gets back to the T=L/R.
Just for the exercise (the values arn't real I dont know what the inductance of a coil is
lets say L =4henry for a single coil and the resistane of the total circuit =8ohms.
then T= 4/8= half a second
now lets assume a single coil resistance is 4 ohms
when we put two coils in parallel we get 2 henry inductance and 2 ohms resistance for the coils
this now gives a total of 2henry inductance and a total circuit resistance of 6 ohms (2 for the coils in parallel and 4 for the rest of the circuit series elements)
so now we get T= one third of a second.
thus quicker risetime.
as you can see this example is slow and the figures are obviously unrealistic but its just to show the concept.
This sytem would run a single cylinder motor at about 23 RPM for the first scenario and up to a whopping 40 RPM for the second, this is because to reach saturation you actually need five T time periods.
You could probably get some similar results by using larger cables to lower the circuit resistance. (that brings up visions of battery style cables or Monster speaker cable connecting up to the coil and distributor can you imagine that sight under the bonnet!)
obviously someone worked out how to do it in the coil alone as Jag went for a single low resistance coil some time later.
HEI, points Its all the same really, wires have resistance and you can't easily overcome it.
The thing about transistors was just that some people think they have no resistive losses and its not true especially of the older junction type devices.
It really gets back to the T=L/R.
Just for the exercise (the values arn't real I dont know what the inductance of a coil is
lets say L =4henry for a single coil and the resistane of the total circuit =8ohms.
then T= 4/8= half a second
now lets assume a single coil resistance is 4 ohms
when we put two coils in parallel we get 2 henry inductance and 2 ohms resistance for the coils
this now gives a total of 2henry inductance and a total circuit resistance of 6 ohms (2 for the coils in parallel and 4 for the rest of the circuit series elements)
so now we get T= one third of a second.
thus quicker risetime.
as you can see this example is slow and the figures are obviously unrealistic but its just to show the concept.
This sytem would run a single cylinder motor at about 23 RPM for the first scenario and up to a whopping 40 RPM for the second, this is because to reach saturation you actually need five T time periods.
You could probably get some similar results by using larger cables to lower the circuit resistance. (that brings up visions of battery style cables or Monster speaker cable connecting up to the coil and distributor can you imagine that sight under the bonnet!)
obviously someone worked out how to do it in the coil alone as Jag went for a single low resistance coil some time later.
#45
rodomo
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Posted 02 March 2009 - 09:13 PM
I wanna know who henry is? 
#46
VitcLJ
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Posted 02 March 2009 - 09:26 PM
ford? 
Higgins?
King of England?
Some dude who played with electro magnets long time ago look ere
http://en.wikipedia.org/wiki/Henries
Higgins?
King of England?
Some dude who played with electro magnets long time ago look ere
http://en.wikipedia.org/wiki/Henries
#47
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Posted 02 March 2009 - 09:33 PM
Still not getting it, you appear to be representing the two coils in parallel as just one circuit element to come up with the faster rise time. However, this doesnt appear to be the case, the coil we have in this circuit that is connected to the ht wire still has exactly the same inductance and dc resistance.My apologies TOP GEAR was on.
HEI, points Its all the same really, wires have resistance and you can't easily overcome it.
The thing about transistors was just that some people think they have no resistive losses and its not true especially of the older junction type devices.
It really gets back to the T=L/R.
Just for the exercise (the values arn't real I dont know what the inductance of a coil is
lets say L =4henry for a single coil and the resistane of the total circuit =8ohms.
then T= 4/8= half a second
now lets assume a single coil resistance is 4 ohms
when we put two coils in parallel we get 2 henry inductance and 2 ohms resistance for the coils
this now gives a total of 2henry inductance and a total circuit resistance of 6 ohms (2 for the coils in parallel and 4 for the rest of the circuit series elements)
so now we get T= one third of a second.
thus quicker risetime.
as you can see this example is slow and the figures are obviously unrealistic but its just to show the concept.
This sytem would run a single cylinder motor at about 23 RPM for the first scenario and up to a whopping 40 RPM for the second, this is because to reach saturation you actually need five T time periods.
You could probably get some similar results by using larger cables to lower the circuit resistance. (that brings up visions of battery style cables or Monster speaker cable connecting up to the coil and distributor can you imagine that sight under the bonnet!)
obviously someone worked out how to do it in the coil alone as Jag went for a single low resistance coil some time later.
I cant see that adding any number of coils in parallel is going to effect the current flowing through the coil with the ht wire connected.
#48
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Posted 02 March 2009 - 09:36 PM
just wait i have a book with this mod done to a car with dyno results give me a sec and i will scan it
#49
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Posted 02 March 2009 - 09:51 PM
Its the total circuit that matters in this case.
What causes the main problem is the parasitic wiring resistance outside the coil.
As far as the coils are concerned when in parallel, for the rest of the circuit, they appear as a single unit even though physically they are not.
you are correct the coil inductance and resistance of the operating coil stays the same
the second coil is also the same.
The single coil current stays the same at saturation but the rise time of the current is faster meaning that you get to saturation quicker so better spark ensues.
the penalty is you need to supply twice the current to the ignition circuit and then throw half the energy away in the second coil. (mostly, as discussed earlier there are other problems as well)
What causes the main problem is the parasitic wiring resistance outside the coil.
As far as the coils are concerned when in parallel, for the rest of the circuit, they appear as a single unit even though physically they are not.
you are correct the coil inductance and resistance of the operating coil stays the same
the second coil is also the same.
The single coil current stays the same at saturation but the rise time of the current is faster meaning that you get to saturation quicker so better spark ensues.
the penalty is you need to supply twice the current to the ignition circuit and then throw half the energy away in the second coil. (mostly, as discussed earlier there are other problems as well)
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Posted 02 March 2009 - 09:52 PM
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