Idea for programmable Ignition for carb'd Rotaries
08-17-12, 02:30 PM
#1
Wankeled 86
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Idea for programmable Ignition for carb'd Rotaries
I just recently got my 12A project up and running but would like a programmable ignition option for it. I currently use Autosportlabs' Megajolt Lite Jr on my 4 cyl 4AGE coupled with Coil On Plugs. Here's what I came up with and I believe this should work.
It would require the following:
2x EDIS-4 modules
2x VR Sensors
2x Megajolt Lite Jr
1x 4 post coil pack
Pin 12 of both EDIS modules just wouldn't be used because the coil for 2 & 3 on a 4 cylinder can't be programmed to spark 20° behind the leading coil even with a separate VR sensor. I don't know of a way to designate a separate one for coil B.
What ever ignition map is used for the Leading coil should be used for the Trailing coil. The location of the Trailing VR sensor 20° after the Leading sensor will just naturally dictate the 20*° stagger.
The only concern now is maintaining good spark above 7500rpm given the limitations of the EDIS units.
Slap me back to reality if I'm day dreaming but this really should work.
It would require the following:
2x EDIS-4 modules
2x VR Sensors
2x Megajolt Lite Jr
1x 4 post coil pack
Pin 12 of both EDIS modules just wouldn't be used because the coil for 2 & 3 on a 4 cylinder can't be programmed to spark 20° behind the leading coil even with a separate VR sensor. I don't know of a way to designate a separate one for coil B.
What ever ignition map is used for the Leading coil should be used for the Trailing coil. The location of the Trailing VR sensor 20° after the Leading sensor will just naturally dictate the 20*° stagger.
The only concern now is maintaining good spark above 7500rpm given the limitations of the EDIS units.
Slap me back to reality if I'm day dreaming but this really should work.
Last edited by dr.occa; 08-17-12 at 02:42 PM.
08-17-12, 06:44 PM
#2
I see what you're doing. You're taking two Ford-style wasted spark coil packs and using one channel off of each. You're hoping that by having another crank position sensor pickup 20 degrees after the main one, you will naturally get a baseline of 20 degrees split like a regular 12A. PIP and SAW is Ford notation that goes way back to the early EEC systems.
Yet I wonder if the real implementation is worth the trouble. Electrical noise could be a major problem. You're assuming that the pickups can resolve the missing tooth easily in both positions. If you're looking for a project, go for it. If this is a boosted engine I wouldn't risk it.
I believe MSD and some other vendors have systems that advance and retard ignition timing on a dizzy. I have seen boosted muscle cars with locked dizzy's using these types of systems with a laptop to set them up. You'd have to buy two of these systems I think.
Yet I wonder if the real implementation is worth the trouble. Electrical noise could be a major problem. You're assuming that the pickups can resolve the missing tooth easily in both positions. If you're looking for a project, go for it. If this is a boosted engine I wouldn't risk it.
I believe MSD and some other vendors have systems that advance and retard ignition timing on a dizzy. I have seen boosted muscle cars with locked dizzy's using these types of systems with a laptop to set them up. You'd have to buy two of these systems I think.
09-30-12, 08:10 PM
#4
If you are using an msd your leading plugs are firing 3times within 20 degrees of rotation. What ends up happening is your leading and trailing at some point will fire at the same time. The trailing system is only to accelerate the flame rate of your fuel at low rpm to clean up idle emissions and is dangerous under boost if adjusted wrong. Long story short if you have msd on your leading you no longer need a trailing system, a direct fire waste spark system with a programmable ignition is the why to go.
Last edited by ghost1000; 09-30-12 at 08:13 PM.
10-01-12, 12:18 PM
#5
Wankeled 86
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If you are using an msd your leading plugs are firing 3times within 20 degrees of rotation. What ends up happening is your leading and trailing at some point will fire at the same time. The trailing system is only to accelerate the flame rate of your fuel at low rpm to clean up idle emissions and is dangerous under boost if adjusted wrong. Long story short if you have msd on your leading you no longer need a trailing system, a direct fire waste spark system with a programmable ignition is the why to go.
10-01-12, 12:50 PM
#6
Wankeled 86
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Just got wind at the AUTOSPORTLABS board on their new Megajolt C programmable ignition unit that "...wasted spark is effective to nearly 10K RPM....". Hurrah!
10-02-12, 08:10 AM
#7
You can't fire the trailing plugs in wastespark. You'll ignite the leading edge of the trailing chamber. Locking split at 20* is a poor option from a performance standpoint as well.
Why not just pick up a cheap used EMS and use only the ignition side? Would be a lot less convoluted, easier to install and program, and would allow the option to go to fuel injection if you ever felt like it.
Why not just pick up a cheap used EMS and use only the ignition side? Would be a lot less convoluted, easier to install and program, and would allow the option to go to fuel injection if you ever felt like it.
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10-02-12, 12:59 PM
#8
Wankeled 86
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It wouldn't be locked per se just like the trailing vr sensor in the distributor isn't "locked". The MJ unit is fully programmable.
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