bill shurvinton

Lynn,



Sorry, missed the bit about the MSD reading your original text. I'll read more carefully next time.



Curious that it worked with a stock ignitor though. I'll have to test that on the bench. Ignition is one of those areas where theory and practice still often have major disconnects.



I'll post some pictures as I go along with the system I am building. The advantage of using the EDIS system is that you get a fixed advance even with no ECU connected. In fact you could build a controller using no more than a 555 as a monostable and a pot on the dash. The EDIS modules are about $40 from a U-pull.

Jeff20B

Bill, so you're saying that a DIS coil on both LEADING plugs is ok (on a 13B), but a DIS coil on leading AND trailing on ONE rotor is bad?



Mike, the setup you had was one FD leading coil per rotor housing, right? You're running six individual coils now with the E11?



Lynn, how about 90º for leading only? So each leading plug sees a spark at 0, 90, and 180 degrees. Do you think 'chamber pressure' would be rather high at that point, thus preventing the spark from jumping very easily?



The MSD basically treats the coil like a step-up transformer. It's best to get a coil that was built with this in mind. If you try to use a tradiational kettering type coil, it will probably burn up.

bill shurvinton

I'm saying that theory says that each coil will get 1/2 power compared to normal wasted spark operation. Accepted wisdom is that rotaries need nice fat sparks, so this wouldn't work well. However Lynn has proved this wrong. I can only assume that it speaks volumes for his tuning prowess in that he had a good (read easy to light) fuel mixture throughout the range.

Jeff20B

There sure are plenty of theories out there. One of mine is to have a dedicated coil and ignitor for each leading plug because it overcomes the shortcomings of a DIS coil. Using cheap readily available parts was just a fringe benefit. I call it DLIDFIS. My 20B ignition is based on it. We'll see how well it works right after I'm done with my current project.

bill shurvinton

Its a fine theory, and if you want fixed timing then you can do it with about 3 ICS and a standard CAS. But I want to be able to adjust advance to make the beast easy to start and drive and give retard when you hit the NOS.



I do have drawings in my lab book for driving standard mazda ignitors from the EDIS, I just wasnt happy about the risks when doing a 4 rotor that wasn't mine.

j9fd3s

yep.



concieveably with lynns setup you could go super old school and put an advance/retard lever on the dash, like a 20's car. or run that cas signal to an ecu



for a roadrace car you bascially dont need an advance curve, although it can broaden the power peak a bit

bill shurvinton

Having a mapped ignition has some advantages. Easier starting, stable idle at lower RPM etc.



But the KISS way of doing things has a certain attraction. I'll go away and try and document up all my notes for posterity, as I came up with about 6 ways of doing it.



I need to escape from the house and get a proper ignition test bed up and running as well.

Jeff20B

Three ICs? As in integrated circuits? That would be kinda cool. I also like the 555 timer idea.



I decided to keep mine simple (because I'm stupid) and just use an FB distributor with three pickups spaced 120º and a stock reluctor in the stock location (bottom of the shaft). I did build a second pickup holder with three more pickups for trailing and a two-point reluctor at the top of the shaft, but the amount of power trailing adds vs the amount of parts needed to accomplish trailing direct-fire could not be justified at the time. Besides, leading ignition with 0º and 180º sparks takes care of the squish very well. I didn't notice a difference while driving my 13B with trailing switched on and off through all sorts of driving conditions. Plus there are no other 20Bs with 0º and 180º sparks, so it seemed like a cool bonus, if unexpected at first (you see, I was under the impression the JC Cosmo did have 0º and 180º leading sparks from the factory, heh).



Trailing does have one nice feature. If the engine has leaky oil seals, when you fire it up after it's been sitting for a while, the leading plugs can sometimes get fouled with oil. This is where trailing shines. The trailing hole is small like one of those so called spark plug no-foulers you can get at the auto parts store. This allows the engine to run while the leading plugs get cleaned by the incoming AF mixture. I've actually experienced this feature once. If it turns out to be something that I truely need, I will setup trailing as soon as possible. Otherwise, I'll just run leading only untill everything else around here is running (I may need to extra coils and ignitors for some other engine around here).

bill shurvinton

You take advantage of the fact that the 2nd gen CAS has a pulse every 30 degrees and a home pulse every 360. divide by 3 and you get a pulse every 90 for a 4 rotor, divide by 4 for every 120 for a 3 rotor and divide by 6 for a 2 rotor. Put the output of a the divider into a simple counter, and reset the counter with the home pulse.



Its so easy its just a pain I haven't had time to knock I up. there are even some $1 8-pin microcontrollers that would do it easily



Bill

Jeff20B

Wow, that does sound easy.