DIM Electronic Advance Ignition

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About rotor phasing, here is my take. A standard V8 rotor and cap accommodates about 40 degrees of crank advance. The locked distributor I have, starts at leading edges of cap/rotor interface, with the falling edge of conditioned pick-up sensor reference signal for base timing. The base timing setting adds to that. If base timing is 14 degrees, then 40 plus that would yield 54 degrees total crank advance. That is more than enough. Some advance by RPM, some by MAP (-vacuum) all by table, so you get what you want, where you want it, and not, if that is desired too.

I have verified using mathematics and in hardware with timing light. I have not tried with a distributor with mechanical advances, and with electronic controls, that does not seem correct to me. My mission has been to eliminate the mechanical components and replace with well proven accurate and reliable electronic means.

Mopar had a good idea with lean burn, however it was flawed in the implementation. It was introduced in the era of primitive electronics, the cost cutting did not help. I am working with devices rated to 125 degrees C, (100C is 212F). Micro controller speeds are 100x, silicon absolute pressure sensors are perfection compared to a diaphragm and pot. The rating on the IGBT coil drive component, are superior compared to bipolar power transistor.

Bill is correct, what I am doing is similar to early to mid 90's OEM systems, with the difference, it is user tunable. By going to cam/crank sensing and coil on plug, or 2 quad coils it would be near current technology.

I also experimented with ion sensing, were a follow on current is applied to the spark plug making it a sensor to view the combustion event. The ion sense is an optimal way spark timing control. It still needs the normal table control, plus additional electronic hardware.
Simple is good for reliability, it might be too complex for that.
 
So this would mean you could record the combustion event efficiency, or just use it as an extremely accurate point for ignition and fuel timing?
Sorry if I missed the point.

Just spend a weekend putting a digital controller with built in adjustable timing and rev limiter to control the 8 pin ECU and get it to market at a good price for the average Joe.
Please? :)
 
The ion current monitoring, provides a signal that has an envelope that provides a view of the flame travel. Timing is all about getting the center of combustion event, that is not instantaneous, at the correct point of the crank cycle, to provide the greatest benefit. That point is typically 10 to 20 degrees ATDC. It is similar to combustion pressure monitoring. It takes sophisticated hardware and software for real-time closed loop control.

Sorry, I do not find a need for the GM 8 pin module in the work I do. I place the VR interface and ignition driver on-board. Fewer wires external wires and lower cost. I checked, and the 8 pin modules seem expensive over the counter.
The other problem is electrical specifications on OEM parts are not well documented in public. I use parts that are well documented to keep operating parameters in specification.
 
Re rotor phasing, my point (and 273Dart67's) is that the mechanical weight advance does not move the rotor tip relative to the tower. This isn't obvious and was argued before on FABO, but you can convince yourself by thinking about when the points open (or reluctor teeth align). When you lock out the weights and apply the rpm advance electronically, your rotor tip will move away from the tower. If too much, it may jump to the wrong cylinder (mis-fire), but you don't want the spark to have to jump far regardless. After-market distributors w/o weights are designed for this with wide rotor tips, as I expect the lean burn one must be (photos?).

I bought a new 8-pin HEI module as backup for $20. But junkyard first to get the connectors too. Any ~85-95 GM truck should work (small cap dist.). The advantage of the 7 or 8 pin HEI module is that you can easily command spark advance. As I recall, it is similar to the SAW square wave tweak used in Ford's EDIS (see Megasquirt).

Monitoring the ion current sounds elegant. It looks like you have been reading SAE technical papers.
 
KitCarlson said:
Sorry, I do not find a need for the GM 8 pin module in the work I do. I place the VR interface and ignition driver on-board. Fewer wires external wires and lower cost. I checked, and the 8 pin modules seem expensive over the counter.
The other problem is electrical specifications on OEM parts are not well documented in public. I use parts that are well documented to keep operating parameters in specification.
Click to expand...

I was speaking from a purely selfish point of view.:D
Be nice to have one to sell with the HEI units that didn't cost a lot.
 
Bill,

About the ion ignition. I did my own development @ 1998, and later found that it was already used on Saab engines. I started by using a CDI unit that I designed and built 1971 for a high school science project. I got an A-. Years later took it off, when I sold my first car, a 1966 Dodge Cornet with a \6. I used it with capacitors local to the plugs, charge resistors and HV diodes for blocking for normal ignition strike. I specially fabricated the units, using bakelite VW Bosch plug terminal ends. My intent was a high energy ignition, it was that. The plugs shot white balls of fire with a pop louder than the old style cap guns, used as a kid. I monitored the capacitor current with a current transformer, and found the flame envelope signature. I used it on my 1963 VW Beetle, with a switch to turn on the HV supply. It made a difference in cold weather when the choke was on, the idle was much improved. I then got sidetracked with job change, and sold the bug. After research, there is a simpler way to inject the current, and at a lower voltage. The 300V was way too much, 80V is more typical and will not erode the plugs.

TrailBeast,
If I am not mistaken the 8-pin GM HEI may work in the limp home mode (analog dwell control as in 4-pin), without computer with a mechanical advance distributor. If a computer controls the spark, a locked rotor distributor with correct rotor phasing is required.
 
I made progress last night in dwell time extension. This enables coil charge to be extended across the timing reference point. For those who wonder, "what is that?", it has similarities to increased dwell with a dual point distributor. However it does not need a second trigger coil. There is always the requirement of about 0.3mS, for the ignition event, so dwell cannot be 100%.

My prior applications with 4-Cylinder engines with quad coils did not prepare me. They had four times more available dwell time, due to multiple coils that could overlap in charge, and fewer cylinders. I was also using two timers to control the events, that actually was simpler.

Single coil V8 ignitions, are limited by the serial nature of ignition events. A good coil, that is quick to charge is essential. I will evaluate several popular coils, for high RPM energy capability.

I will also check operation with a MSD CDI unit.
 
KitCarlson said:
I made progress last night in dwell time extension. This enables coil charge to be extended across the timing reference point. For those who wonder, "what is that?", it has similarities to increased dwell with a dual point distributor. However it does not need a second trigger coil. There is always the requirement of about 0.3mS, for the ignition event, so dwell cannot be 100%.

My prior applications with 4-Cylinder engines with quad coils did not prepare me. They had four times more available dwell time, due to multiple coils that could overlap in charge, and fewer cylinders. I was also using two timers to control the events, that actually was simpler.

Single coil V8 ignitions, are limited by the serial nature of ignition events. A good coil, that is quick to charge is essential. I will evaluate several popular coils, for high RPM energy capability.

I will also check operation with a MSD CDI unit.
Click to expand...

Keep in mind that MSD multiple spark only happens up to 3k RPM's.
Then it drops to a single spark.
As far as I know anyway.
 
TrailBeast,

My unit would server as the trigger, the MSD would do its thing, no change from mechanical advance distributor, other than user tuning with electronic advance.

I have a friend that is a great power supply designer. It might be possible to make unit with recovery, and capacity for multi strike to 6K, with the right coil. Switch mode power supply technology has improved significantly over the years. We have worked a few projects together, his products are high performance and reliable.
 
KitCarlson said:
TrailBeast,

My unit would server as the trigger, the MSD would do its thing, no change from mechanical advance distributor, other than user tuning with electronic advance.

I have a friend that is a great power supply designer. It might be possible to make unit with recovery, and capacity for multi strike to 6K, with the right coil. Switch mode power supply technology has improved significantly over the years. We have worked a few projects together, his products are high performance and reliable.
Click to expand...

Ok, got ya.
"multi strike to 6K" I was wondering if you were wondering about that. :D
 
It's alive!!!

I installed the ignition today, it works well with guesstimated tables. Next is verification of timing on the engine, and optimize advance tables.

It took longer than expected, got carried away adding features in hardware, firmware, and application software. It will work for /6 and V8, also added a secondary advance control for applications that need a retard table by electrical contact.

I hope to post screen shot pictures and data logs by the end of the week.
 
Watch out,,,,I think I hear a crowd with torches and pitchforks coming up the driveway!

Seriously though, this is interesting to see.
Is this setup going to be user variable via PC or handheld device, or a set initial and curve?

Nice work.
 
Thanks for the reply,

All the above. However not required for normal driving. It replaces many instruments including tach, vacuum gauge, voltmeter, real-time engine timing in degrees ... For those with in car PC, or other devices.
 
Sell them?
That is a good question. I may consider it in the future. People that have observed the system, often say I have something, and it would be a waste not to sell. I am a bit selfish at the moment. I am doing this, to satisfy my requirements for, an optimal user tunable system. It has useful features, not found on other systems. I am holding back on details.

I am an experienced product development engineer. I have developed robust, reliable, profitable devices, for large companies. The companies had large internal support groups, to handle many details including manufacturing, marketing, technical documentation, support, distribution ... It is just me now, too many hats at the moment. The other work may be beyond my skill sets, and does not interest me as much.

My test install was truly plug-and-play, no wires cut or spliced. Harness options for various A-body years and engines, could be a design project by itself. Mainly differences in wire length for connections. The hard part may be to find all the variations.

I need to enjoy the fun of development first. I like the hardware design, mechanical aspects, firmware and application software development.

When I think the system is ready, I will reconsider selling. Then, if I can recruit help, it may be possible.
 
Thank you for the interest.

Since this part of the forum is not for selling. It might be best for those interested, to PM me. I will add you to a potential buyer list. If the list is long enough, by the time I am ready. I will become a FABO sponsor, and start to sell units.

Meanwhile I will continue to post the progress and features. Also post your ignition feature, wish lists. That information will help me decide the future road map for next generation products.
 
You are correct about the 8 pin module having a limp home mode.
The the white wire terminal of the four pin connector controls advance and if supplied with 5 volts DC will retard the timing by 10 degrees. (limp home mode)
I don't currently know what a forced intake engine needs for a retard amount, but since I currently cannot vary this as it is a set amount, I can't incorporate a user settable advance or timing curve.
I talked to the guy that made the Rabid Gator timing computer, and he said "just use a Megasquirt EFI computer and only use the timing functions"
At $400 just for the build it yourself kit, I can't justify that price wise.
I just want an HEI ignition system where the user can set the base, curve and total timing from the drivers seat with a interactive readout.

Too much to ask right now it seems.
 
trailbeast,

HEI?
My system is high energy, however it does not use the GM module. The one box system has an internal solid-state switch for the coil, the micro-controller controls dwell and ignition timing. The GM module would be additional parts, wiring, bulk, and expense. There is no need for it.

It is too early for price, that changes much with build quantity. Some depends on how much is included to make it totally plug-and-play. Having the complete harness, coil, distributor, and plug wires, would make a near fool proof install. The components would be excellent quality, and verified to work well with the system.

About a controller.
Your HEI setup uses a mechanical advance distributor, controlling the timing over that, would be a disaster. Good control systems, have a single driver behind the wheel.
 
I'm sorry, I was rambling about my stuff and I think you thought I was talking about yours.
Adding to it, I was referencing a post from back aways.

I just meant that using the controller I am using, it would be nice to electronically set the base, curve and total timing instead of mechanically.

Sorry about that.
 
Trailbeast,

It is OK, now I have no idea what you are talking about.

The GM 8 pin module is not a controller. It is a VR interface with dwell control and current limit, all this is analog circuitry. There is not a micro-controller inside. To add a timing controller is possible, but using it on a mechanical advance distributor would be silly.

While some think the Mopar box is an ECU, it is an VR (pick-up sensor interface) and an output transistor to drive the coil. It does not incorporate the dwell or current limit control. It requires a ballast resistor to limit the current and the excess dwell wastes energy and heats the coil. The GM module is an advantage over the Mopar box. In your present application, it is running in the limp home mode, in conjunction with mechanical advance.
 
KitCarlson said:
Trailbeast,

It is OK, now I have no idea what you are talking about.

Sorry :D

The GM 8 pin module is not a controller. It is a VR interface with dwell control and current limit, all this is analog circuitry. There is not a micro-controller inside. To add a timing controller is possible, but using it on a mechanical advance distributor would be silly.
I know this, and never meant to sound like I was suggesting the two together.

While some think the Mopar box is an ECU, it is an VR (pick-up sensor interface) and an output transistor to drive the coil. It does not incorporate the dwell or current limit control. It requires a ballast resistor to limit the current and the excess dwell wastes energy and heats the coil. The GM module is an advantage over the Mopar box. In your present application, it is running in the limp home mode, in conjunction with mechanical advance.
Click to expand...
Exactly, on all points.
All I was saying was I'd like to figure out how to inexpensivly be able to set base, curve and total timing with the module I use.
 
Trailbeast,

For your needs the megasquirt less FI may be your best option. Even at that you may end up with changes in the firmware and application software. Not sure about design rights, or the ability to resale.
 
KitCarlson said:
The GM 8 pin module is not a controller. It is a VR interface with dwell control and current limit, all this is analog circuitry. There is not a micro-controller inside. To add a timing controller is possible, but using it on a mechanical advance distributor would be silly.
Click to expand...
I think the GM 7 or 8-pin module does have some smarts in it. Probably not a microprocessor, but dedicated digital circuitry. As I recall, it outputs a square wave which an external spark controller can return with a delay to set the desired spark timing. This is similar to the Ford EDIS module but a different input (distributor, not 36-1 crank wheel) and a single coil output.

Several after-market ECU's can interact with the GM 8-pin module. The Holley Commander can connect directly w/ optional cables.

I don't think a timing controller with mechanical advance is silly. The controller just adds to the mechanical advance. This has the advantage of allowing a fairly accurate "limp home" mode, as well as keeping the rotor tip better phased to the posts, plus requires no buggering with the distributor. The disadvantage is that the weights can stick and be erratic, but if your controller is constantly advancing to a knock limit, that "comes out in the wash".
 
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