coil Per cylinder
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coil Per cylinder
coil per cylinder this is an idea that has been playing around in my head for a wile has anyone done any reserch into making it work or how one could make it work.....
Ok done a Little work on this and I have come up with a little compremise(spelling). I e-Bayed 4 Renault Pencil coils and conected them to a spare EDIS modul in two banks IE coil one and four where conected to out put A and coil two and three to out put B with a positive feed to all four and an neg to each the coils sparked great this is not true coil percylinder as there still fireing in banks of 2 but gets rid of the big ford coil pack and gives direct Ignition which is very nice need to do quite a bit more work on this befour I post pics but Its a start and Im chuffed.
Regards all,
Merlin.
Regards all,
Merlin.
Very useful research, thank you.
Please measure the primary coil resistance for the two coil packs connected together, so we can compare it against the EDIS module.
Also, could you measure the secondary resistance on a single coil pack as well?
I have some Ford/Mazda coil-on-plug units as well- I'd like to compare your measurements with mine.
Thanks,
Please measure the primary coil resistance for the two coil packs connected together, so we can compare it against the EDIS module.
Also, could you measure the secondary resistance on a single coil pack as well?
I have some Ford/Mazda coil-on-plug units as well- I'd like to compare your measurements with mine.
Thanks,
Sorry for the crosspost, but I'm doing a coil per cylinder application with a Lexus V8, using the EDIS8, and have their primaries wired in parallel to fire in waste spark mode. Since this motor's firing order is 18436572, I have the following pairs: 1-6, 8-5, 4-7, 3-2. Each coil's primary measured 0.9 ohms, so the load at each EDIS output is around 0.45 ohms. Pics of the installation and the spark produced are here: http://www.autosportlabs.org/viewtopic.php?t=1457
I'm not sure what to think of the spark; I would have liked to have seen a white ball of fire and a very loud "snap", but it seemed a bit on the puny side to me. It was definitely audible, and visible, however.
These are Toyota Supra coilpacks, which are accustomed to igniting fuel & air under fairly heavy boost, in cars up to 1000 HP, so I think they should be man enough.
Any comments welcome; I'll be hooking the motor to an engine dyno in a couple of weeks.
I'm not sure what to think of the spark; I would have liked to have seen a white ball of fire and a very loud "snap", but it seemed a bit on the puny side to me. It was definitely audible, and visible, however.
These are Toyota Supra coilpacks, which are accustomed to igniting fuel & air under fairly heavy boost, in cars up to 1000 HP, so I think they should be man enough.
Any comments welcome; I'll be hooking the motor to an engine dyno in a couple of weeks.
Over the hill, low on compression, and sometimes not firing on all cylinders, just like my cars.
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Oliver Sedlacek
- Posts: 68
- Joined: Mon Sep 13, 2004 8:45 am
- Location: The Chalfonts
- Contact:
If you wire primaries in parallel, the output will be pretty feeble because each coil will only charge to half the usual current. As the stored coil energy is proportional to the square of the primary current, you will only get a quarter of the spark energy.
If you wire the primaries in series, you will generally get full spark energy at low rpm but you may run into trouble at higher rpm. The inductance of the two primaries are added in series, so the dwell time doubles, and you may run out of dwell time.
If you wire the primaries in series, you will generally get full spark energy at low rpm but you may run into trouble at higher rpm. The inductance of the two primaries are added in series, so the dwell time doubles, and you may run out of dwell time.
Oliver thanks for your comments, but IMHO, I think your logic is flawed.
Inductors act as resistors, and when you put them in parallel, the impedance is halved and the total current to the circuit doubles. So, if anything, I would be concerned about frying the EDIS from too much current.
As you said in your 2nd paragraph, putting the coils in series would double the inductance, (and thereby halve the current), and as a result I would think this would keep the coils from charging fully.
But why the spark "appears" weak at fairly low RPM is still a mystery, (to me anyway).
Inductors act as resistors, and when you put them in parallel, the impedance is halved and the total current to the circuit doubles. So, if anything, I would be concerned about frying the EDIS from too much current.
As you said in your 2nd paragraph, putting the coils in series would double the inductance, (and thereby halve the current), and as a result I would think this would keep the coils from charging fully.
But why the spark "appears" weak at fairly low RPM is still a mystery, (to me anyway).
Over the hill, low on compression, and sometimes not firing on all cylinders, just like my cars.
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Oliver Sedlacek
- Posts: 68
- Joined: Mon Sep 13, 2004 8:45 am
- Location: The Chalfonts
- Contact:
The EDIS, like most electronic ignition systems, performs adaptive dwell timing. The dwell time is adjusted until the coil current reaches a pre-determined level at about the time the spark is due. The typical coil current level is set to 6 or 7 amps inside the EDIS, and this is why the EDIS doesn't burn out when you load it up with two coils.
The primary resistance of modern coil packs is 0.5 to 0.6 ohms, which means that connecting them directly across a 12V battery would charge them up to 20A or so. This will saturate and melt the coil (after all 20A times 12V is 240W), so the current limiting of the ignition driver is a critical part of a modern system. The resistance of the coils isn't generally too significant. On the other hand, the inductance, which is generally in the range 4mH to 7mH, determines the rate at which the coil can be charged up. Doubling the inductance halves the initial rate of current rise, so the dwell time becomes much higher.
The primary resistance of modern coil packs is 0.5 to 0.6 ohms, which means that connecting them directly across a 12V battery would charge them up to 20A or so. This will saturate and melt the coil (after all 20A times 12V is 240W), so the current limiting of the ignition driver is a critical part of a modern system. The resistance of the coils isn't generally too significant. On the other hand, the inductance, which is generally in the range 4mH to 7mH, determines the rate at which the coil can be charged up. Doubling the inductance halves the initial rate of current rise, so the dwell time becomes much higher.
Thanks Oliver, you just jogged my memory. From past experience, these Supra coilpacks and their external smart ignitor module don't like to be connected to a waste spark setup and "want" to be connected to a true sequential ignition system where they only fire on compression stroke, as they do with the OEM setup.
When the coilpacks have been connected in a waste spark system with an aftermarket ECU, the the car ran "just" OK until the turbo came on boost, then it falls on its face with ignition misfires. The addition of an ignition amplifier module such as the HKS Twinpower DLI sorts it out, however I must admit I don't know the details of how it works. Perhaps it raises the voltage in the primary circuit, so that even with the current limiting of the ignitor, the coils have a fighting chance of charging?
I had hoped the problem with the Supra waste spark setup was the smart ignitor which, it was suspected, doesn't function correctly with an aftermarket ECU that wants to control dwell itself, and doesn't require or care to receive feedback from the ignitor. But perhaps the real culprits are the coilpacks themselves?
So as you stated in your first post, rewiring the coils in series would probably sort out the weak spark at lower RPM, but the system could run out of dwell time, and spark at higher RPM. I wonder if there's a way to predict, without a 'scope, at about what RPM it'll run out of spark?
Secondly, I wonder if using coilpacks with integral ignitors would sort the overall problem, and the EDIS would then simply control the triggering of the ignitors to charge the coils? But maybe due to the very small current draw of the trigger circuit, as compared to the main charging circuit, the EDIS might allow too much dwell time, and the integral ignitors would allow the coilpacks to fry themselves?
When the coilpacks have been connected in a waste spark system with an aftermarket ECU, the the car ran "just" OK until the turbo came on boost, then it falls on its face with ignition misfires. The addition of an ignition amplifier module such as the HKS Twinpower DLI sorts it out, however I must admit I don't know the details of how it works. Perhaps it raises the voltage in the primary circuit, so that even with the current limiting of the ignitor, the coils have a fighting chance of charging?
I had hoped the problem with the Supra waste spark setup was the smart ignitor which, it was suspected, doesn't function correctly with an aftermarket ECU that wants to control dwell itself, and doesn't require or care to receive feedback from the ignitor. But perhaps the real culprits are the coilpacks themselves?
So as you stated in your first post, rewiring the coils in series would probably sort out the weak spark at lower RPM, but the system could run out of dwell time, and spark at higher RPM. I wonder if there's a way to predict, without a 'scope, at about what RPM it'll run out of spark?
Secondly, I wonder if using coilpacks with integral ignitors would sort the overall problem, and the EDIS would then simply control the triggering of the ignitors to charge the coils? But maybe due to the very small current draw of the trigger circuit, as compared to the main charging circuit, the EDIS might allow too much dwell time, and the integral ignitors would allow the coilpacks to fry themselves?
Over the hill, low on compression, and sometimes not firing on all cylinders, just like my cars.
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ImpressIVPower
- Posts: 4
- Joined: Sat Sep 06, 2008 12:55 am
sorry to come in late on this discussion, but...
does any know exactly how the ford coil packs are wired internally?
i would have guessed that each half is in fact just two coils wired in parallel, and therefore indistinguishable from a coil on plug setup, save only the physical location of each coil. perhaps there is one primary and two secondaries. whatever its internal configuration, the end result is the same as if you wired up two separate coils in parallel, ie two sparks occurring at the same time which should amount to the roughly the same amount of energy, which should amount to roughly the same amount of total current being switched by the EDIS.
one barely related comment: there has been some discussion about higher compression mixtures requiring stronger sparks to ignite them. my feeling is that while that is true, it is not true that a more highly compressed mixture will 'draw' a stronger spark and therefore more current. it will be the same spark, releasing the same amount of energy. i think the issue for hi compression motors is whether or not the spark created is sufficient.
alexander.
does any know exactly how the ford coil packs are wired internally?
i would have guessed that each half is in fact just two coils wired in parallel, and therefore indistinguishable from a coil on plug setup, save only the physical location of each coil. perhaps there is one primary and two secondaries. whatever its internal configuration, the end result is the same as if you wired up two separate coils in parallel, ie two sparks occurring at the same time which should amount to the roughly the same amount of energy, which should amount to roughly the same amount of total current being switched by the EDIS.
one barely related comment: there has been some discussion about higher compression mixtures requiring stronger sparks to ignite them. my feeling is that while that is true, it is not true that a more highly compressed mixture will 'draw' a stronger spark and therefore more current. it will be the same spark, releasing the same amount of energy. i think the issue for hi compression motors is whether or not the spark created is sufficient.
alexander.