With a 6A here's a trick that will improve the performance a bit.

The first gen guys figured out that you can wire 2 stock coils in paralell.

It of course haves the resistance increasing the power, but not beyond what the 6a can handle, as many of the performance coils have very low resistance, lower even than 2 stock coils in series.

If you use 2 trail coils you can mount them both to the stock lead ignitor with some small spacers between them.

This also gives you better performance because it gets you out of single coil wasted spark, as there is only one spark gap for each spark to jump.

Intersting.

So your basically saying, run another set of trailing (individual coils/1 post per coil) coils without their ignitors, using the single ignitor from the original leading coil....with the MSD wired in between?

yeah thats what I'm saying.

The first gen guys figured this out a long time ago as an extension to the dual igniter system. Its a way to run distributerless ignition (lead only) on a first gen without an ecu.

When I had a 1g I had planned to do this, and called MSD to confirm it wouldn't hurt the box. The engineer told me that it would probably run a whole rail of coils.

The stock lead coil is really a single coil, like the trail coil, that has two outputs. Off hand I believe that the outputs are in series but it doesn't really matter how they are. When the stock coil fires the spark has to jump 2 gaps. Using two coils, still has the spark as a waste spark, but it only has to jump one gap.

The MSD can't tell the difference between 1 and 2 coils, all it can see is resistance, and current draw of the coil.

Just to make sure I'm not giving you bad advice, I called MSD tech support (5 min ago) and they said: "Is this a mazda RX7, yeah no problem people do that all the time" and that the coils will just draw as much current as they can and there is no issue with coil resistance, also he said that it will produce as much power out of one coil as it will out of 2, and there would be no advantage to having one msd box per coil.

True. I don't need alot of thing but manage to do it anyhow. I just bought the FJO kit today so I will be running it for sure this year. Without upgraded igntion. Just going to run good plugs and good wires.

Hope BDC can tune AI.

I came across this page, with a wiring diagram.

Has anyone noticed that they have the Leading and Trailing coil labeled on there, I think they are talking 0 split with that drawing

Yes but you don't need to do it like that, I was suggesting using 2 coils in series both for leading.

lol, I feel silly but this thread has done me well.

However, I currently don't have a use for the info as I went balls to the wall on my ignition setup:


https://www.rx7club.com/attachment.p...1&d=1204555429

https://www.rx7club.com/attachment.p...1&d=1204555429

https://www.rx7club.com/attachment.p...1&d=1204555429

Jacob's pro street amps, and Jacob's coils, 10mm magnecor wires, stock ingitor.

I did something similar, but I used the 120 dollar summit boxes (x2) with a pair or accell super coils that have been in my garage forever.

I mounted them in the front bumper core.

Questions: what cylinder select settings does the Jacobs have (8cyl, 6cyl etc)?

Also what are the input types?

My guess is that like the MSD digital 6 and even the cheapo summit box I have its designed for 4,6 and 8 cylinder engines with distributors.


Which means that if you have it in 4 cylinder mode and run discrete channels to the lead coils, the box will see and use for its multi spark calculations exactly half of the true RPM.

hmmm, good qeustion but I'd have to check and I'll look tonite.

IIRC there's only a rev limiting switch on the amps.....I don't recall any cylinder # settings....

Hopefully Jacob's answers this email lol

It has to have a cyl select, because its method of sensing RPM for rev limiting and for multi spark calculation is through its own triggering input.

If it doesn't have cyl select then it can only work in one configuration

it was suggested to me by a senior Jacobs tech guy to keep the amps separated by at least six inches... all wires to and from the amps should be shielded. i really like my Jacobs amps. in addition to putting out lots they have a circuit that senses acceleration and goes to full power. if you don't have such a throttle down around town circuit you end up frying your plugs very quickly. my ignition fired my pump/methanol cleanly at 9.0 AFR. (of course i don't know why i was running that rich but have since leaned it out)...

as far as the rev limiter wires. (there are 2 loops on my amp) you need to cut one of the loops and it will count revs properly for a 2 rotor. i have my rev limiter turned off so it doen's make much diff.


http://img88.imageshack.us/img88/733/p1000696ba8.jpg


my leading coils. MSD 8253. perhaps my ignition is overkill but it takes that factor out of the equation. i will be interested to learn how a single MSD 6A functions as it would be an easy mod.

http://img147.imageshack.us/img147/9356/p1000690to3.jpg

hc

Hmm, six inches eh? I guess I may have to rethink mounting solutions....

Thanks for the tip Howard...

The separation shouldn't matter if they are firing off the same signal at the same time.

Sorry to semi bring this back from the dead. I too am getting my ignition all setup, and I was wondering if it is required to get two ignition boxes like Howard Coleman and classicauto have done? I have an FC I will be running a little meth in to cool and have a little extra safety margin, and would like to make sure I don't have any ignition breakup when Steve Kan tunes it this summer.

Thanks
~Tweak

One on the leading is probably good enough, especially if you run a good dual coil or a pair of coils in parallel as is shown further up.

I'd like to note that one of the Jacob's amps crapped out in short order while idling. I'm currently running stock coils for the moment but will be installing the MSD 6A I bought at the onset of the thread.

I am sorry to hear that your Jacobs died, I was thinking about snagging a little FC1000, but I guess I will pass. I was thinking about getting the super high 1,200 Millijoules Crane Cams ignition boxes, I have access to an MSD 6a also, so I think I will grab that. Also I didn't get much feedback when I searched for Crane on the forums.

Are you going to be using one or two boxes, and are you going to do the stock coils in parallel trick, because I think I would like too, but I don't quite understand what is going on with that.

Could someone maybe throw up a little mspaint diagram to give a little example of the parallel trick? Is it just two coils plugged in, but only one spark going out?

Thanks
~Tweak

When I get around to the MSD 6A I'll be boosting the leading coil only using a single MSD 6a box, wired as per slo's MSD diagram on post #31

Ok, I don't know much about our cars ignition system, I definitely need to read up on how it works. I was a little confused on how it said, leading and trailing, but I think I got it all figured out now.

Thanks
~Tweak

BIG Correction on the above diagram, it should say leading coil number one, leading coil number 2. not leading/trailing if you hook it up with dual post coils like that you will blow your engine up

Use this instead

The original pic is clearly designed for a car with a distributor, but it shows that MSD themselves endorse hooking their box up in parallel to 2 coils which is what I wanted to show.

Good to know thanks. :D

I am thinking about getting 4 of these so I can fun full sequential ignition.


http://stores.bmepefistore.com/Detail.bok?no=11

"These BMEP EFI High Output DIS coil feature a built-in transistorized ignitor, perfect for use with OEM and other aftermarket ignition systems that don't have high current coil drivers and must otherwise rely on an external Power Stage (Ignitor) or CDI. For example, many OEM Motronic systems have very low current, high side coil drivers that must be used with an ignitor, these external ignitors are unreliable and limit current to the coil. Also, some systems like the Haltech or AEM EMS use these same, low amperage drivers which often requires a $1k CDI box to even use the system with a conventional coil. BMEP EFI High Output DIS coils with built in transistorized driver allow a high current, 20 Amp driver to be integrated with one of the most powerful coils on the market, giving over 60k-100k Volts of spark energy w/o any other ignition boxes or components. "

From what reviews I have read from people that have used them, it will ignite anything, and they didn't use a CDI box.

What do you guys think? Anybody seen/used them here?

Thanks
~Tweak

transistorized driver=ignitor

What they are describing is an integrated coil and ignitor like LS1 coils, as opposed to coils with separate ignitors, like stock.

Their clams are BS:

"external ignitors are unreliable and limit current to the coil"

nope...

I am willing to bet that what they are selling is LS1 coils.

Dang it, right when I think I find the perfect solution ... it's always too good to be true. :(