90 replies to this topic

[FastEHHolden]

I used to use that setup for ages..works very well

[rodomo]

I removed a cap from an old lead and placed it on top of the second dizzy as the electronic ones protrude out from the coil. If using points fill the hole with something like silicon or arildite as long as the arildite can handle the temps to stop spark escaping.

A pic would be good. I'm having trouble with this bit.
(But I have trouble with lots of things )

[rodomo]

Thanks for the pic but what does this achieve?

[TerrA LX]

Glad someone asked.

[Rockoz]

The voltage generated in the secondary coil of a transformer is the result of the collapsing magnetic field in the primary when the voltage is taken off.


Now I studied applied electricity many years ago, and I may have forgotten something, but I cant see how adding an inductive load is going to achieve much here.

Im thinking that if you joined the secondaries together you would get a fatter spark as you have doubled the available current. However you would need to make sure the coils were phased the same, otherwise it would be detrimental to the operation.

From memory, the idea behind seperate coils is to give them a longer charge time, building a stronger magnetic field, that when decaying will generate more power in the secondary.

But these systems, or a least the ones I have seen, each coil feeds some spark plugs.

What you have suggested only seems to increase the parasitic load.

[rodomo]

Found this:
"12 cylinders at 8,000 rpm requires a spark every millisecond and a standard coil isn't be able to provide enough current. Jaguar moved to twin coils later in production, and these can be easily retrofitted to earlier cars."
Here:
http://autospeed.com...le.html?&A=0274

[Joshua]

i don't get it either...

doesn't' the coil have three plugs, positive, negative and the one to the distributor...

but this is being wired so the second coil has no output(to distributor)... so won't it just be doing nothing?

[FastEHHolden]

the primary coil builds up its magnetic field but it has nowhere to collapse thru...so it collapse thru the primary coil of the other coil that does have an output.

[VitcLJ]

Now seriously guys! I've been working with electronics for over 40 years. Designed systems for medical use ( may even have been up some of forum members proverbials looking for the dreaded colon cancer) and this theory sounds to me like black magic or "orgone" energy. How the hell a collapsing magnetic field in one coil can affect the secondory voltage or for that matter the secondary current in another coil is something I cannot work out. Please explain (to quote a famous Aussie politician) .

Simple pictures or words will do we dont have to get into the DI/ Dt formula for inductors if you dont want too.

The Electronic module in standard ignition systems (not MSD or ICE or other clever primary voltage boosting
types that use real world methods) is at its heart just a transistor acting as a switch instead of the points, it increases the dwell angle over the old points system so the primary current has more time to rise to its maximum value particurlarly at high revs.

Placing two coils in parallel as suggested will increase the current the transistor needs to switch, this will increase the heat dissipated by the transistor and will shorten its life. Even though the transistor is a switch it spends a finite time in the on to off (firing) state and in the off to on (charging state) . This switching time does not change significantly with current through the transistor so power dissipation will rise.

once again I'll stay away from the formulas but be assured if you can give logical provable reasons for this system working I would like to hear them. You never know the method will probably be patentable and worth a fortune to electronic power supply manufacturers.

[Rockoz]

the primary coil builds up its magnetic field but it has nowhere to collapse thru...so it collapse thru the primary coil of the other coil that does have an output.

To put it simply................................................. No way.

For the magnetic field in one coil to have any tangible effect on another coil, they have to be inductively linked.
In short, they need to share the same iron based core.

If this gained horsepower I will call trickery.

Multi coil systems share load.
LS1 V8...............8 coils..........1 per cylinder.

V6 Ecotec..........3 coils............1 shared by 2 cylinders

Havent seen an L34 setup in the flesh but reckon 2 coils, each running 4 cyl

If you want to get a good increase in usable horsepower, turn off your alternator during accelleration.
Automatic gain of a couple horsies.

[rodomo]

More Jag stuff:
A 12 cylinder engine running at 6000 r.p.m. has just 1.666 thousandths of a second between sparks. It is asking rather a lot of a contact breaker to function at this rate and give acceptable life so it was obvious right at the outset that the V12 would need some sort of electronic ignition system. Fortunately Lucas had already developed their OPUS system for high revving racing engines so there was no need to look any further and with minor changes over the years it served the V12 reasonably well for its first decade, running with conventional centrifugal and vacuum control of ignition timing.
The HE with its 12.5:1 compression and lean mixtures was even more demanding but by this time constant energy ignition systems were available which could maintain a consistent charge current through a low resistance coil over a wide speed range. A clever trick was still needed to meet the abnormal energy requirement of the HE V12 - the coil had a second, non-firing, coil connected in parallel thereby doubling the rate at which energy built up in the system. A centrifugal advance mechanism was retained but because of the large amount of advance needed by the HE engine to burn lean part throttle mixtures the vacuum advance system became a complex mass of pipes, valves and solenoids that worked better than it looked. The long term reliability of such a system would always be questionable so the need for long term emission control durability meant something better would be needed, however this system remained in limited use on Series 3 V12 saloons into the early 1990s .

[VitcLJ]

This thery though still looks suss to me. Inductors in parallel act like resistors so yes you will get a decrease in the time taken for the energy build up but half of the total available energy gets wasted by the unterminated coil.

Also I would hazard a guess (mind you its only a guess) and say the second coil would only have a primary winding. In that case the fundamental frequency of the spark would be higher giving a better risetime. however the trigger system would have to be designed to run the extra primary current.

This (only having a primarywinding) would also overcome the extremely high voltage that is produced by the unterminated secondary of the second coil in the original set up shown here. Its fine to say use silicon to insulate the HV terminal but this wont overcome the stress placed on the coil internally and it will eventually fire across windings and burn out. this may not show up at all in the normal running circuit but will once again cause higher currents through the transistor and shorten its life. (you can't destroy energy so if the secondary does not fire it will appear as heat and probably radio waves (ignition interference anyone?).

If anyone really needs this sort of ignition power and can legally use them, (in group N (Historic)racing in Australia you can't, they have only recently allowed us to run the standard electronic system from the later Holden straight six motors) spend the dollars and buy the MSD or ICE system that is designed to provide it with componentry that can function efficiently with no waste or hassles.

yeah I know "waffle waffle waffle" I should have been a teacher! (NO WAY ! )

sorry POPS there are more than two lines together, its the dreaded BLOCK text. Then again you probably haven't even read it (HEE HEE says sarcastic b@#stard)

[rodomo]

The thing I have learnt through this thread is that unless I can get my six spinning to 12,000 rpm, I shouldn't have a problem with the H.E.I with 1 coil?

[FastEHHolden]

Simple fact is when i had this twin coil system setup running with splitfire plugs it would run very differently when you took the 2nd coil out of the circuit...you could run very big gaps with no problems.....or in my case you could gap a plug to 1 mm and not worry about it until it ate 0.5 mm off the electrode.

Pretty much don't care how big your brain is..it works.

I used this system after reading an article siting its use on old Jags.

i know its hard on plugs..I'm sure it would eventually bugger a coil...but I don't listen to AM radio so i wasn't worried too much.

[VitcLJ]

Rodomo Id say thats about it!

If you do get it spinning to 12000 please please can you put up pictures and machinists addresses etc as I would then follow you down that path!

Then we can try for 20,000 and next the WORLD (maniacal laughter follows )

[rodomo]

No sarcasim from me, like I said, I've learnt something being the reason why.
If I do get my 6 spinning to 12k, how big is your wallet?

Edited by rodomo, 28 February 2009 - 10:32 PM.

[FastEHHolden]

I used this system when i went to gas and was still running points ignition.....I now run HEI.

BTW...I have a box full of points dissies and coils...I don't however have a box full of MSD's...total cost must be about $2.

[VitcLJ]

geeze some people are touchy.

I asked for a logical explanation and Rodomo supplied a link that made sense.

I would hope that we all learned something from this thread.

If you feel I shoudn't ask for explanations or offer any advice on the forum then just tell me and I will shut the F%$K up and just become another plant in the garden.

The size of one persons brain is pretty much the same as anothers. I know things you dont, you know thing I dont and If I posed a question about what you know on the forum I would be happy to hear any thing you had to say.

The majority of problems on forums arise from these sorts of issues and I for one would hope that we dont go there too often.

If I offended anyone in anyway I apologise but Hey I wanted an answer.

It obviously works, I reckon it has its down side, the guys at BOSCH who designed the system probably optimised it for long life and durability personally I wouldn't use two coils with it , I would buy the MSD system.

I like to be able to drive home and have been stranded twice already on the road with a failed ignition module in a holden straight six. I reckon the use of two coils on a single module would up the chances of that happening again.

Mind you moble phones mean a lot less walking now adays if it does happen.