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Author Topic: High Energy Ignition discussion  (Read 1391 times)

chrispoe

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High Energy Ignition discussion
« on: June 12, 2015, 11:37:21 PM »

While we are on the subject of ignition - I've toyed with the idea of replacing the internal ignitor with a more robust external one. Some of the V6 mazda folks had issues with theirs and switched to using an external GM HEI ingitor. They're significantly cheaper than the stock ones, a lot more common, and supposedly more robust. I may have talked about this here before, but what are your thoughts? It shouldn't be terribly difficult to wire up. I think we would need to fabricate a small spacer for inside the dizzy where the old ignitor bolted down, but that would be about it.

Theres some info available by googling "GM HEI mod"
Here's one I read not too long ago: http://www.clubprotege.com/wil/howto/hei/

Iíve read about people doing the GM HEI mod on probetalk, and figured if/when my ICM fails on my V6 in my probe I would do the upgrade and finally use the Blaster coil thatís been sitting around for the last 15 years.
When I did my BP swap I used all of the escorts ignition system.

As you can see it the pic, Iím already running an ECM controlled external ICM thatís mounted to the fusebox bracket.

Hereís my take on the GM HEI mod for a capri.
You canít remove the stock ICM from the Inside of the distributor.
The first problem I see is the ICM is installed on the breaker plate inside the distributor which rotates to advance and retard ignition timing.  Removing it would leave you with no control of timing.
The second issue is that the internal ICM is triggered by the 4 point star armature that spins next to the ICM. If you were to remove the internal unit, how would you trigger an external unit?

You also canít use the the pick-up as a trigger either because it only pulses once for every 2 rotations of the crank so it wonít provide a signal for 3 of the 4 cylinders. Itís also fixed inside the distributor so it wouldnít give you any advance/retard of the ignition timing.

You could try to drive the GM module with the tach signal from the ICM, then just use the GM HEI to drive the ignition coil. This would greatly reduce the electrical load on the internal module and should increase itís life exponentially.
« Last Edit: June 13, 2015, 03:15:12 AM by chrispoe »
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Rocketman

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Re: High Energy Ignition discussion
« Reply #1 on: June 13, 2015, 03:50:30 PM »

(I've split this topic from the original thread as it warrants it's own thread)

On my XR2 distributor the ignitor is mounted to a a fixed plate within the distributor. The vacuum advance moves a 2-pole armature with magnets around the 4-point star, allowing for vac/boost timing adjustment. (this part moves, ignitor stays still) When the points of the star line up with the armatures, it closes the magnetic field, inducing a current into the coil below it, which triggers the ignitor to fire the coil.

Since the igntitor is on a fixed plate, it can be moved externally.
I'm pretty sure the N/A is set up the same way.
The N/A's external module can remain where it is.

As a slightly different aside, the ignitor itself is the part that does the high-current switching for the ignition coil, correct? I know it is not done from the ECU.
What's stopping us from putting a beefy MOSFET next to the ignition coil, and putting the switching load on that? They make some really compact high-power, fast switching MOSFETS nowadays. Pull the load away from the ignitor and put it elsewhere, it should significantly reduce the heat in the ignitor?

Isn't that essentially what the bit is on your Escort ignition setup?
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Rocketman

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Re: High Energy Ignition discussion
« Reply #2 on: June 13, 2015, 04:15:14 PM »

I've somehow missed the fact that there are two modules inside the XR2 distributor. There's also a pickup for TDC signal, just above the 4x pickup.

I'll have to pull my oscilloscope out and see what's up with these bits
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chrispoe

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Re: High Energy Ignition discussion
« Reply #3 on: June 13, 2015, 10:23:57 PM »

(I've split this topic from the original thread as it warrants it's own thread)

On my XR2 distributor the ignitor is mounted to a a fixed plate within the distributor. The vacuum advance moves a 2-pole armature with magnets around the 4-point star, allowing for vac/boost timing adjustment. (this part moves, ignitor stays still) When the points of the star line up with the armatures, it closes the magnetic field, inducing a current into the coil below it, which triggers the ignitor to fire the coil.

Since the igntitor is on a fixed plate, it can be moved externally.
I'm pretty sure the N/A is set up the same way.
The N/A's external module can remain where it is.

Is the pick-up and the igniter one assembly or are they separate pieces? I donít have a XR2 distributor to play with so Iíve been going off the FSM distributor diagram. It shows the pick-up and igniter as one unit. 
The FSM says the star is the armature and the braker plate contains the poles that rotate.  Then again looking at the diagram for the N/A and comparing it to whatís on my workbench , I trust the FSM as much as the dealershipÖlol
Does the pick-up just plug directly into the igniter like the N/A? If the pick-up coil is separate, then it might be possible to drive an external GM HEI after all. 
 
Also, the N/A's external module is pretty much the equivalent as the second module inside the XR2 dizzy.

As a slightly different aside, the ignitor itself is the part that does the high-current switching for the ignition coil, correct? I know it is not done from the ECU.
correct

What's stopping us from putting a beefy MOSFET next to the ignition coil, and putting the switching load on that? They make some really compact high-power, fast switching MOSFETS nowadays. Pull the load away from the ignitor and put it elsewhere, it should significantly reduce the heat in the ignitor?

This in my opinion would be another alternative, although I was thinking of a IGBT instead of a MOSFET.
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Rocketman

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Re: High Energy Ignition discussion
« Reply #4 on: June 14, 2015, 01:38:44 AM »

IGBT may be a better choice. I am not on the up & up with my electronics like I used to be.

I did some digging on my XR2, and perused a few wiring diagrams.
The output of the dizzy is fed into the knockbox, and the knockbox feeds the coil directly. So im not sure where the coil is actually being driven from yet.

The XR2's pickup coil plugs directly into the ingitor on the XR2. The ignitors look nearly identical, but the n/a has 3 terminals, the xr2 has 2.
The pickup under the distributor's dust cap appears to be the same between the n/a and XR2, at least looking at the FSM

FSM also recommends installing the ignitor with a heatsink/dielectric compound. That probably wears out over time

Still thinking the GM 4-pin HEI may work, I have an old one laying around here. As well as a distributor to experiment with

Also, the FSM calls the same part by 3-4 different names depending on where in the FSM you are looking. Pickup, ignitor, g-sensor...etc c'mon.
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chrispoe

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Re: High Energy Ignition discussion
« Reply #5 on: June 14, 2015, 04:04:15 PM »

I noticed too on the schematics that the knock box is wired in between the igniter and coil and was wondering the same thing of where the coil is actually driven.  If I had to take an educated guess though, I would say the igniter is still the primary switching source. Without opening up a knock box and looking at the boards components, I canít say for sure.  You could determine the switching source with a clamp-on AC/DC ammeter by comparing tach signal amp reading going in and out of the knock box.

So the pick-up coil is a separate piece, now I see where youíre heading with this. I would try to use some washer as the spacers or even better, make a clamp/spacer to hold a set of ground shielded wires in place that connect to the pick-up coil.
If you canít get the GM HEI to work,  you could just use the stock igniter and relocate it along with the filtering capacitor to a heatsink on the firewall. It would definitly be easier to replace it if it ever failed again.
Thereís two ways to increase the life of the stock igniter. Make it switch a smaller load so it generates less heat or move it to a cooler location to keep it cool. So moving it to an extenal heatsink would cool it better than being stuck inside a 200+ dergee dizzy.

The FSM does showís the CID sensor under the cap on both the XR2 and the N/A.  But the FSM is wrong, the N/Aís have the CID sensor located outside the dizzy.
« Last Edit: June 14, 2015, 04:07:20 PM by chrispoe »
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Gaz

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Re: High Energy Ignition discussion
« Reply #6 on: June 17, 2018, 03:13:50 PM »

Necro'd for America.

I assume this is doable, then? How does this compare to the 6al?
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