I am currently using a 300m coil on plug setup. In short it sucks, it cannot deliver enough voltage to create spark when my car sees large amounts of cylinder pressure.

I will start with saying I do engine diagnostics work from 8-5 mon-fri so I am pretty familiar with most ignition systems, unfortunatly in my area there isnt a huge amount of japanese imports so I don't get to play with alot of ignitors/transistors.

My 300m coils are wired in series just like most other people have done. I have never lab scoped the primary side of the ignition system on the car but I would assume it is supplied with b+ like most domestic ignition systems, so with a resistance of .7 ohms(300m coil) that would give you 1.4 ohms wired in series so about 8.5 amps of current flowing through the circuit, and if you wired them in parrallel that would give you a resistance of .35 ohms and 34 amps which is obviously more than the transistor and 14 gauge wire would like to see on most days.

So if you used two transistors wire like this:
trans 1 circuit a to cylinder 1
trans 1 circuit b to cylinder 2
trans 2 circuit b to cylinder 3
trans 2 circuit a to cylinder 4

Would this be a safe posible way to supply 12 volts to each coil? I would also think another capacitor would be nice to reduce noise.
__________________

The current flowing through the circuit is dependent on the inductance of the coil(s) as well. An inductor resists change in current flow, so when the transistor grounds the coil, current ramps slowly, and increases exponentially. The question is just how much current is flowing when the transistor turns the coil off, since that is the stored primary energy 1/2L*I^2. Typically, COP units are fairly low inductance and should charge pretty quickly by themselves. When in series, assuming no mutual inductance is occurring (more likely on 2 and 3 than on 1 and 4), the inductances add together like resistors in series. This will increase the necessary charge time.

I'm not certain, but I think the power transistor units have an internal 6A current clamp to prevent damage to the power unit in case of a short. I think that's the bottleneck.

I would run a separate igniter for each coil. The Bosch BIP373 is cheap enough to run one on each coil, and (I forget what the ignition trigger looks like, whether it's inverted or not) might be able to be driven directly off the ECU. With the Bosch transistors, you'd be halving the inductance of the circuit (faster charge) and adding 3A of current under the clamp. 50% more charge current nearly doubles the spark energy.

Hey man,good to see ya round still but although i may not be following you correctly ( it's late and i workeda double shift in construction today) but if you're talking about having the wire from one ignition channel split to 2 ignitors, i have seen it hooked up like theat on a guy's car here locally because he was getting way more mis-firing than he should have at his boost level with his COP ( but he was using motorcycle coils) but anyway, each channel was split to sink 2 ignitors off one channel from the ECU and as far as i know it was still that way when the car was sold.

I'll try and double check with him tomorrow on this, and if i'm way off course, just tell me to shut up

turboglenn said:

Hey man,good to see ya round still but although i may not be following you correctly ( it's late and i workeda double shift in construction today) but if you're talking about having the wire from one ignition channel split to 2 ignitors, i have seen it hooked up like theat on a guy's car here locally because he was getting way more mis-firing than he should have at his boost level with his COP ( but he was using motorcycle coils) but anyway, each channel was split to sink 2 ignitors off one channel from the ECU and as far as i know it was still that way when the car was sold.

I'll try and double check with him tomorrow on this, and if i'm way off course, just tell me to shut up

Click to expand...

thanks very much for the input guys.

What I was trying to say was 1 channel per coil, 1 ignitor has 2 channels so it would run 2 coils, and the other ignitor would run two coils. Just hook both up to the ecu.

yea, that's what' i'm talking about , one ignitor runs the coils for 1&4 and the other ignitor runs the coils for 2&3 splitting the pull to ground wire that triggers the ignitor into both sides of that ignitor ( or both channels)

turboglenn said:

yea, that's what' i'm talking about , one ignitor runs the coils for 1&4 and the other ignitor runs the coils for 2&3 splitting the pull to ground wire that triggers the ignitor into both sides of that ignitor ( or both channels)

Click to expand...

Thats actually a differant but good enough idea. I am setting it up for both of the ignitors to trigger non companion cylinders, and splitting the ecu triggers to both ignitors.

So mine will fire 1&2 and the other 3&4.

I almost got it done. Scoped stock ignition system, and cop in series.

What were the results on your setup? Did it work?

I would like to know as well. I was thinking about doing this.

Has anyone complted this mod, and got it to work?

I have read that it helped 1 guy get around his missfire problem. I am in the process of developing a sequential ignition splitter to turn the 2 factory signals to 4 independent signals. This is going to eliminate the wasted spark system and allow us to run a 4in 4out igniter or coils with a built in igniter. This is the coil i plan on using- http://www.bosch-motorsport.com/pdf/components/ignition_coils/Coil_P100_T.pdf

If this this works, it will allow people to make a lot more power, and have better running car. Is this able to be done with two stock igniters?

TurboAnything said:

I am in the process of developing a sequential ignition splitter to turn the 2 factory signals to 4 independent signals. This is going to eliminate the wasted spark system and allow us to run a 4in 4out igniter or coils with a built in igniter.

Click to expand...

I built a similar setup to split the single ignition channel on the honda ECU that controls my 3SGTE. Kind of surprising more people haven't done it, considering it takes all of 3 IC chips.

Given the use of individual coil drivers, however, I really don't think there's any reason to switch it to true direct/sequential ignition from the stock wasted spark setup. The only reason to split the signal further would be if the dwell times were overlapping each other, which they should not be doing anyway.

Honestly though, what you're talking about is how the COP setup should have been done all along- 4 coils, each with built-in ignition stages that only require a TTL signal to drive. The coils are cheap enough now that you can pick up a set for about what a set of 300M coils cost and they each have their own power stage built in. The toyota 1ZZ coils work very well, as do 350Z/altima coils (proven to well over 700whp in 4cylinder applications).

polarmoment said:

I built a similar setup to split the single ignition channel on the honda ECU that controls my 3SGTE. Kind of surprising more people haven't done it, considering it takes all of 3 IC chips.

Given the use of individual coil drivers, however, I really don't think there's any reason to switch it to true direct/sequential ignition from the stock wasted spark setup. The only reason to split the signal further would be if the dwell times were overlapping each other, which they should not be doing anyway.

Honestly though, what you're talking about is how the COP setup should have been done all along- 4 coils, each with built-in ignition stages that only require a TTL signal to drive. The coils are cheap enough now that you can pick up a set for about what a set of 300M coils cost and they each have their own power stage built in. The toyota 1ZZ coils work very well, as do 350Z/altima coils (proven to well over 700whp in 4cylinder applications).

Click to expand...

Can you brake this down alittle more? If you have some type of diagram or instrustions, I will put this on my car and post findings

It did not work. I tested it with a lab scope and found the reason why.

The ignition coils wired in paralel ramped current to fast. Anything that creates an electromagnetic field pulls an increasing amount of current over time until it is saturated or shut off(fired in the case of an ignition coil). If there was a way to adjust ignition dwell this may have worked fine, I am not sure if the 300m coil could deliver the energy that a stock dsm coil could but this would give it alot better shot. It over worked one of the ignitors and burnt it up in the process.

Thomas Dorris has discussed adjusting dwell with a factory ecu and dsmlink and said it is a very complicating bit of software required to make it possible. You could of course adjust dwell with a stand alone ems, but at that point you would be better of using individual drivers and firing the coils sequentially anyways.

I hope this helps. But I do not recomend 300m coils for a performance upgrade. They look nice and save room, but underperform.

Dwell adjustment could be done with hardware too. Use the ignition signal to charge a capacitor through a resistor to make the leading edge of the ignition trigger into a slope. Feed that slope to a comparator and use an adjustable voltage source (pot) as the reference to control where on that slope the comparator output turns "on." Discharge the capacitor through a diode to maintain the trailing edge of the signal to fire the coil at the proper time.

I'm kind of surprised a single 300M coil on each channel could burn out a power transistor. The inductance must be tiny on those if they're charging to damaging current levels that quickly.

Almost makes me wish I still had a DSM to try this stuff out on

Install a DIS-2 or equivalent and be done with it.

Hal

Spln_Hrd said:

If there was a way to adjust ignition dwell this may have worked fine, I am not sure if the 300m coil could deliver the energy that a stock dsm coil could but this would give it alot better shot. It over worked one of the ignitors and burnt it up in the process.

Click to expand...

I thought this post looked familiar. Didn't I tell you you'd burn up the ignitor when you posted this on dsmlink? I guess it is still useful to watch it for yourself. Did you see the transistor come out of saturation as you killed it? I found that interesting to watch.

If the 300M dwell is considerably shorter, and you are charging it to the same max current to keep the ignitor alive, do you think it is going to store as much energy? The formula to use is (1/2) I*I*L. The (1/2) is constant, the I squared is constant, the L.... well if one coil takes half as long to get to 7A as the other, which one would you bet has the smaller inductance?

Spln_Hrd said:

I hope this helps. But I do not recomend 300m coils for a performance upgrade. They look nice and save room, but underperform.

Click to expand...

Welcome to what I have been telling people for as long as they've been wasting the money on this conversion. Their response is usually along the lines of"yeah, but it looks cool and cleans up the wiring!"