I'm not really concerned with dyno tests and stuff like that, if that's what you were asking.

I need to correct something I said earlier. A few posts above, I said the late trailing plugs fired after the normal leading and trailing in the R26B. This is not true. It actually fired all three plugs at the same time. The late trailing plug fires into the squish zone (trailing edge) of the rotor face. Well, guess what? DLIDFIS and every other direct fire ignition system that sparks both leading plugs at the same time accomplishes something similar to the R26B's late trailing plug. This is due to the fact that DLIDFIS (etc) fires the leading plugs 180 degrees after they initially fire, and ignites the air fuel mixture in the squish zone (trailing edge) of the rotor face without having to resort to a spark plug up near the oil galley (under where it says Mazda in raised letters). I like to call it Late-Leading.

I wonder how the R26B would have ran if they would have sparked the leading plugs 180 degrees later? It would have given the rotor faces four sparks per rev instead of three.

Speaking of three (two actually, since I'm not running trailing right now), my 20B already has a Late-Leading ignition system that I've decided to call TLIDFIS (the T stands for triple, hehe). It's the only 20B out there with it, as far as I know. It has a spark event every 60 degrees, just like an even-fire V12. It is hard to tell how it's going to run once it's all set up with EFI, but if the temporary carb setup was any indication, it's going to sound a little different than your typical (single leading spark) 20B.

Also, my single rotor 13B will have Late-Leading as well. It will require a few dizzy mods outside of what Dave Atkins does on his single rotor engines, if I want to run trailing. Otherwise, leading ignition only will require no mods (I'll get to keep the stock four tip reluctor). I can't wait to give it a try and compare the sound to one of Dave's engines.

Speaking of Late-Leading, did you know the RX-8 doesn't have it? Yep, it only has one leading spark and one trailing spark per rotor face. Why? It's because of the nature of its MSPRE (multisideport rotary engine). They needed to have some unburned AF mixture, along with some exhaust, enter each intake phase. My guess is that since the exhaust doesn't exit through a peripheral exhaust port, this was necessary. I'm curious what would happen to the emissions and runability if someone were to add Late-Leading capability to its ignition system. Paul Yaw may be our only hope at this point. Can anyone get ahold of him to ask?

 

Well I am planning to go and attemp getting the parts outta the wrecker tomorrow... all I will need is the unit that the spark plugs will plug into from a 2nd gen? nothing more, like maybe 2nd gen wires? I am new to ignitions, and upgrading them.

 

I think 2nd gen wires are a little too long, unless you plan on installing the 'unit' really far from the engine (as it is in the 2nd gen engine bay). Grab 'em if you can get a good deal on them. Otherwise, leave 'em.

 

think this would be safe to run on a turbo 12a setup? i know in theory it sounds great; but the chance of spark "going wrong" somehow would be catastrophic in my situation now. i don't really see how it could, but just asking for any theories that would maybe keep me from wanting to do this. thanks guys!

-zac

 

As long as the leading coil is triggered only once every 180 degrees of E shaft rotation, it'll be fine. That's how 13B turbo engines run. It's up to you to determine how much advance to run.

 

Awsome Work!!! Make this a sticky.

 

Done. Took about twenty minutes and cost $20. Wow, what a difference all around!

 

i'll give this a shot. i think my friend has a couple coil packs lying around. WOOHOOO!

 

I have two MSD 6AL boxes. I'm thinking I use a 2nd gen CAS with them. There are 4 wires to it. If I run those wires to the msd boxes and run the msd boxes to the coil packs, it should work. Right???

 

negative, i believe the second gen cas was controlled by it's ecu.

 

No, I don't think so. The signal from the CAS goes through the ECU or something like that... I think that it's explained soewhere... a search will yield some results, but you'll still have a bunch of reading.

 

The CAS outputs a signal that has no form of mechanical advance. It also hase more teeth than what you'd want to try to run your engine with. Just use a 1st gen dizzy with a 6AL on leading with a 2nd gen coil.

You could use your other MSD on trailing if you want to, but there won't be an improvement. It's kind of a waste of $150-200. I guess the only good thing about it would be the use of the rev limiter. My solution with my MSD 6AL on leading only is to wire up a switch on the dash (or anywhere convenient) to turn trailing off if I know I'm going to be bouncing off the rev limiter. Ask peejay if this is a good idea.

Speaking of improvements from converting to direct fire, my friend dropped off his '77 REPU with a 7" supercharger and FB dizzy yesterday. I'm going to install DLIDFIS when the weather clears up. If it doesn't improve the runability, we'll throw in a freshly rebuilt S5 T2 engine to replace the S4 6port that may have lost an apex seal a few weeks ago (maybe it just cracked because mid to high RPM is still ok). We already tried MMO and swapped in some different plugs (brand new B7EM, which were just laying around), but it was only a small improvement. I guess I'll find out when I'm done.

 

So your saying under no circumstances should I do this. With a fully streetported turbo set-up race motor, this would be of no effect or just a waste of time.

 

So your saying under no circumstances should I do this. With a fully streetported turbo set-up race motor, this would be of no effect or just a waste of time. www.cardomain.com/id/rotorhead37

 

You can go ahead and do it, by all means. It'll give you rev limiters on both ignition circuits.

It's just that trailing sparks through tiny little holes and is physically incapable of adding very much to the engine, regardless of what's driving it (whether MSD or a stock ignitor). My advice would be to use the MSD on another engine, if you had another FC leading coil AND another engine to play with. Otherwise, just install them both on your current engine and enjoy the rev limiting action.

I've noticed time and again that a lot of people don't understand trailing's function at first. Since most of us came from the piston world, it's perfectly understandable to think that each spark plug has an equal duty to perform in the engine's power production. If you take an inline 4 cylinder for example, it would run really poorly if only two spark plugs were working. This is not the case with a rotary. It would be best to imagine a 2 cylinder engine with one normal spark plug in each cylinder head, and another spark plug which fires through a tiny hole a few degrees after the normal ones fired. To be honest, we could spark the two normal plugs together every 180 degrees which would send a spark into the exhaust 'stroke' just like modern waste-spark ignition systems (which spark cylinders 1 and 4 together, followed by 2 and 3 together). This imaginary 2 cylinder engine would need to be in an even-fire arrangement, so no V-twins. You'd also not want to fire the two other plugs at the same time because even though they're sparking through tiny holes, since they spark a few degrees later, there is a chance at least one would ignite the incoming air/fuel mixture. It's best to leave them to spark seperately, just like the trailing ignition on a rotary.

Anyway, if you're thinking with pistons on the brain, then making the trailing ignition system as powerful as possible makes sense. Otherwise, just leave it stock and move the trailing high tension wires over to the leading part of the cap to take advantage of the carbon button. It's just that simple.

By the way, it's a horrible idea to enlarge the trailing holes in the rotor housings, unless you like excessive blow-by. If so, I've got some rotor housings with missing chrome that you would absolutely love.

 

No I understand the difference of rotary and pistons. I do build both with high horsepower. I also understand the use of a single set of plugs. Some time ago I had an ignitor wire pull loose and was only running on the trailing plugs. It took me a while to figure out the problem or rather find the source of the problem but I kept driving it until I did. I never thought of only running two plugs on leading on purpose. I do figure the trailing plugs to burn the extra fuel I pump in for the new setup.
I have a 91 with a engine rebuild underway. Contemplating the CAS arrived from a brain hurracane seemed to only make sense since this is the ignition system that has been upgraded for both 2nd and 3rd gens. This car is going to be a daily driver since I've done so much to the first gen and won a couple trophys from the nationals with it. I'll post pics of the new power plant when I get it done. Its not in yet, I'm still waiting for the motor to arrive from CP Racing. It is in route now. I hope to have it in by the nationals this year. www.cardomain.com/id/rotorhead37

 

Well I did that mod yesterday to my car. I am clueless about ignition systems, but all is well. I did notice a mild increase during the but dyno, mostly in 1st gear I would say. Is this mod gonna be made into a sticky? I think it should. Just my 2 cents. Total cost - $11.40 thats like what? $7.00 U.S. ? NICE!

 

So this will work on a 80 ignition? If it will I will do this today...

 

Sure. I even have a few '80 distributors to experiement with... eventually. Which components (ignitors etc) are you going to use? (Sorry, I don't have the time to reread this thread to see if you've already mentioned it)

 

I have the J105's installed. Can I just replace them with J109's later? Just got a 2nd gen coil. I think I will install this tommorow.. Thanks for all the help

 

I believe it'll be a simple swap. However, the reluctor of an '80 distributor has a different shape and the J-105s seem to trigger on the opposite voltage. The way to remedy this is to swap the green and red wires. Simple. Of course you'll want to confirm this before making any wiring changes. Plus if you had an '81-'85 reluctor kicking around, it you might want to consider swapping it where the '80 style is.

Then again, it may not be necessary at all. These are all just observations I've made of the differences. I've never actually used any '80 parts on any of my engines other than a gutted J-105.

 

Could you do this but use the 2nd gen ignitor aswell?

As in make the pickup wires in the dissy longer and feed that signal into the 2nd Gen ignitor?

Basically the same as DLIDFIS, except using a more compact package?

Or does the ignitor use a different signal?

 

The 2nd gen ignitor does infact require a different signal. It also does not have any dwell circuits inside like the 1st gen ones do. Some people have tried it hooked straight to a 1st gen pickup though. I certainly wouldn't recommend this because the pickup signal at low RPM is too low to trigger the 2nd gen ignitors (no spark at cranking RPM = no start).

I don't remember the exact procedure, but there is a way to hook a J-109 or J-105 to a 2nd gen leading ignitor for a really great spark. I think all your questions will be answered in this thread here. http://www.nopistons.com/forums/inde...howtopic=40326 Even I learned something. 83turbo basically corrected all of my misunderstandings of the FC leading ignitor and stuff (I was just working with the info I got off of Mazspeed, which turned out to be wrong). He also did some testing with an '80 dizzy. Check it out!

 

We need somebody to put this into a drawing w/step by step photo's???

 

Attached is a pics with both wires. I want to make sure I wire it correctly...