morganson's COP S-Type setup

[Rollus]

Interesting.

Will 30A works if our igniter limits the current?

 

[Rollus]

Morganson,

What about this?

I need to organize the scope images a bit before posting them. Way to many measurements that can be shown off one image. Makes it a cluster to see things.

The short story is this. Im almost certain the ignitor performs current sensing. A block of dwell time is provided that should allow the coil to fully charge, then current limiting takes place until the ignition event is triggered. The times listed below are from coil shorting (begin to charge) until current limiting takes place.

Stock 2.96-3.16ms
IS300: 3.16-3.2ms
Ford: 4ms+ (2 coils wired in series)

The ford coils do not reach the current limiting state at any rpm except idle. The ignitor appears to calculate a dwell window based off rpm, all calculated internally. This window has always been 3ms+ even as rpms increase. What you see on the scope is that the dwell window may 'shrink' a bit, but the coil has enough time to charge to current limiting state. Usually this window is 3.5ms-4ms as rpms increase.

At 6500rpm, the ignitor has 9.231ms per 360degrees of crank rotation. Coil for 1/6 fires every 9.231ms. Plenty of time and duty cycle left over to allow things to cool on the coil side. The stock coils need about 1-2ms to recover after a firing event, judged by the burn duration and oscillations. This varies a bit though.

The stock coils appear to be CDI coils with out a capacitor. Very low resistance. The Is300 coils are 0.6-0.5 ohms, stock 0.4-0.3ohms, ford 1.0-0.9ohms.

Installing a sense resistor to test the current ramp of each coil tonight. I believe the ford coils may be reaching a sufficient charge, although not the current the ignitor expects to see. Even if these are wired in parallel, the current limiting of the ignitor will prevent additional charge.

Once the ignitiors current limiting value is known, it should be easier to plan what will work best going forward.

^ No Problem. Im going to start another thread in the next few days that will cover all of this and what I have found about the ignitor and all its signals. Clever little device!

in the mean time, the ignitor current limits to 7.2-7.6 amps (limit of mV range (X) of waveform i saved) Call it 7.5 amps. The ford coils do not reach this current at any rpm over 1,000rpm or so. They should always be close to this charge level but will rarely hit it. So there output might be limited. I do not have any way to analyze the secondary side so actual output of the coil in KV/mJ is still unknown.

I've seen a few graphs of the dg508 coils needing only 5 amps or so for a full charge. Its very likely the slight undercharge is still producing an effective spark output. Especially when compared to stock 25 year old coils. Have yet to see any OEM application that push the coils to their max. The lower charge should help them run cooler too.
These could be run in parallel to reduce the charge time. Nothing I can really think of to increase the current limit though.

make sure you guys thank supraguy@aol, these are his coils i have been testing on..

 

[morganson]

Interesting.

Will 30A works if our igniter limits the current?

When you wire the booster in you bypass the ignitor and power the coils directly. This actually solves several problems.

 

[Rollus]

I can't see how the coils would be fired without the ignitor.

Can you please elaborate? (a little schematic would help me here)

 

[morganson]

The 12v doesnt have to come from the ignitor. If you seperate that then it cant limit the amp then.

 

[Rollus]

Oh, OK, I thought current limiting happened on coil ground.

 

[morganson]

Why cant this thread get stickied???

 

[morganson]

Oh, OK, I thought current limiting happened on coil ground.

Do you know if anyone has looked into adjusting an ignitor to allow for higher spark output? I dont have access to any of my stuff for a while so i cant look. If the problem is the ignitor limiting the output, and using boosters has a minimal affect. The solution would be to pass the trigger/grounding signal through a circuit that will 1)protect the ignitor and ecu, 2) increase the current in the circuit in a controlled manner.
Easier said than done.
Forgive me if i am overly simplistic in my thinking, i know just enough to get me in trouble.

 

[noel]

what happens after 14psi of boost with this set-up? fyi good work on this set-up!

 

[morganson]

I had no problem at 15psi but that was the max I could go with the simple supporting mods I had.

 

[noel]

okay Good so i should have no problem running 13psi no spark blow out? Also where did you source your coils?

 

[morganson]

Ebay, if you have an ffim there are some higher output options by msd and accel. If not, you need the dg500 to clear the pipe. The wire up could apply to 2jz coils as well as they are also 2pin dummy coils.