Smart Coils, Speeduino, Hall Effect, etc. - New ignition control ideas

[Jcary85]

Hey All,
I've become mildly obsessed with ignition control recently... I've always hated MSD TL as its antiquated and unreliable. Zeel is fantastic and I've used it on all my setups so far. Every back-to-back test so far has shown almost no performance difference but recent testing on my TPE 12 showed enough bottom end gain to make it worthwhile (It wants to be over-rich down low and zeel can't burn the extra fuel).

So, I've toyed with loads of alternatives to MSD but the one I like the most is:

• Speeduino open source ECU. Based around an arduino, so it's cheap. Can handle up to 4 cylinders and lots of trigger types. Can fire smart coils. No built in standard coil drivers.
• Use mini hall effect sensor (55100 type sensors) and a trigger wheel somewhere - either rear mounted or a wheel sandwhiched between flywheel bolt and flywheel
• Use "smart coils" - smart coils are used in many applications and they have the coil driver built in. For example, MSD makes an LS1 engine coild. They take their own +- 12v wire and a low voltage (TTL) signal from the ECU, so the spark energy is determined by the driver in the coil. I'm sure there's some smart coild out there than can output a similar spark energy to the MSD TL

Things I'd Like to Try:
- I still don't know what pickup type the MSD pickups are. They aren't reed switches and they aren't hall effect sensors. If anyone has the term for what type of pickup they are, that would be helpful as I'd love to see if i can make this work with MSD stock pickups
-Possibly look at RusEFI as an alternative ECU


I'm mostly dropping this thread here so I feel the pressure to actually do something with this idea hahah. Open to any thoughts/suggestions.

-Jordan

 

[kevbo]

Finding more power is easy, use an automotive ignition. This will allow the use of a larger plug gap although Im not sure it will help much with firing an overly rich mixture. The cons are more battery draw and less salt water tolerance.

 

[Storbeck]

I'm not super familiar with speeduino but my first concern would be if it is made out of components that are kind of "automotive grade", will it handle the heat/humidity and noisy electrical environment? I'd be tempted to go with a microsquirt instead, but not familiar enough with the two to know if that is just a false impression.

Also isn't the advantage of the CDI that it has a much faster rise in voltage relative to automotive type inductive coils and thus more resistant to fouling which is more important for two strokes vs automotive? This is based on a hazy memory of reading about this in Jennings or Bell so again not sure.

Seems like if you need more zap than a a common zeeltronic can do wouldn't it make more sense to use a dual input/output zeel with two coils and no wasted spark for a little more zap than the "standard" wasted spark setup most people are running?

 

[Storbeck]

Also, selfishly I want you to do it and post up how it goes.

 

[Jcary85]

I'm not super familiar with speeduino but my first concern would be if it is made out of components that are kind of "automotive grade", will it handle the heat/humidity and noisy electrical environment? I'd be tempted to go with a microsquirt instead, but not familiar enough with the two to know if that is just a false impression.

Also isn't the advantage of the CDI that it has a much faster rise in voltage relative to automotive type inductive coils and thus more resistant to fouling which is more important for two strokes vs automotive? This is based on a hazy memory of reading about this in Jennings or Bell so again not sure.

Seems like if you need more zap than a a common zeeltronic can do wouldn't it make more sense to use a dual input/output zeel with two coils and no wasted spark for a little more zap than the "standard" wasted spark setup most people are running?

I don’t think wasted spark is causing any loss

The coils I’m talking about using aren’t standard automotive coils. They are “smart” coils. This means the driver is built into the coil. Essentially, the circuit that does the capacitive discharge is in the coil body, not the ignition control module. The commonly used smart coil out lotus over 100mj of spark energy - more then double zeel.

 

[Jcary85]

Finding more power is easy, use an automotive ignition. This will allow the use of a larger plug gap although Im not sure it will help much with firing an overly rich mixture. The cons are more battery draw and less salt water tolerance.

That’s a pretty general statement. There’s lots of automotive ignitions that could work, sure. My concept could work with sny automotive ECU also but speeduino is simply a cheap one to test the concept with.

 

[Storbeck]

I don’t think wasted spark is causing any loss

The coils I’m talking about using aren’t standard automotive coils. They are “smart” coils. This means the driver is built into the coil. Essentially, the circuit that does the capacitive discharge is in the coil body, not the ignition control module. The commonly used smart coil out lotus over 100mj of spark energy - more then double zeel.

Wouldn't X amount of energy going to one spark give you a hotter spark than the same amount of energy divided between two sparks?

Also, I could be way off but I think the automotive coils are inductive type aren't they? The energy is stored as inductance in a coil rather than as charge in a capacitor as two strokes typically do. This type of coil has a slower rise in voltage than a cdi. Or at least that is what I recall reading.

 

[Jcary85]

Wouldn't X amount of energy going to one spark give you a hotter spark than the same amount of energy divided between two sparks?

Also, I could be way off but I think the automotive coils are inductive type aren't they? The energy is stored as inductance in a coil rather than as charge in a capacitor as two strokes typically do. This type of coil has a slower rise in voltage than a cdi. Or at least that is what I recall reading.

Ya you are correct but I think these AEM style coils will solve that https://blog.racedom.com/aem-high-output-igbt-inductive-smart-coil/

 

[Storbeck]

From Jennings, see image below

I know that the Jennings book is very old and a lot of things have changed since then, but I have seen this other, more modern places and I think the fundamental point that cdi's do, or at least CAN, generate the rise in voltage more quickly than an inductive coil is still true. I can remember reading somewhere about how part of the design of a CDI ignition is a compromise between fast voltage rise and length of the "pulse" so to speak, both having tradeoffs.

In the text he describes how the fundamental problem with battery voltage driven inductive coil ignitions for two strokes is the slow (relatively) rise time of the spark voltage which makes them much less tolerant to fouled plugs than a magneto or CDI.

I know the info from the jennings book is very old, but I know I've read similiar things elsewhere, here is somethign from motec that says about the same thing:

Here is something from Motec that somewhat agrees: https://www.motec.com.au/ac-is-abou...ignition systems produce a,450 V) to the coil.

I think it is important to be careful when applying info meant for four stroke automotive applications to two strokes. Unfortunately there is way more info out there about four stroke stuff.




But also...go try it and see. It will be cool and I want to see what happens.

 

[Jcary85]

Sorta related interesting read. Would be interesting to build my own CDI circuit and drive it with speeduino/etc

Multi-spark CDI Circuit - Homemade Circuit Projects

The post explains an enhanced multi-spark CDI circuit which is universally suited for all types of automobiles. The unit can be built at home and installed in a particular vehicle […]

www.homemade-circuits.com

 

[Jcary85]

eh nvm thats using AC current from an alternator.

 

[2lick]

To scientific for me - nothing constructive to add other then motivation If anyone has the determination to make it happen, you sure do!

 

[kevbo]

We are already lighting the mixture with plug gaps down to .016". Any more energy allows for a wider gap, which is only necessary for mixtures that are much leaner than we can use. So what problem are you trying to solve??