So I'm researching a direct fire conversion for the 12a and after reding SMG's how-to I'm curious if it is nessecary to make this into a hybrid system utilizing the distributor and the MSD. I'm learning, but still new to the rotary world. The dual spark plug system makes things complicated. I'd love to know if I could simply use a triple MSD system, one for the primary plugs, and the other two for the Trailing Plugs. My brain may be completely curfuffled on the whole system but it seems like if I don't want to use the distributor at all I'd need to use 3 boxes. Or am I waaaay off base here?

Better yet, does anyone have any information on how to do it eliminating the distributor completely? I'm pretty good with old school stuff on V-8s, but I'm new to the high performance stuff and what not. Never dealt with direct fire but I have also never planned a turbo build so I'm trying to learn as much as I can about some of the other things that are gonna increase performance and utilize the power I'm putting into this thing.

Thanks folks!

 

If you don't use the dizzy then I assume you will be using some sort of index wheel
or CAS to feed the signal to a standalone computer to manage the ignition system.

The MSD still has to be told when to fire, its not a standalone computer. So you
have to either use the dizzy signal or some other device to tell it when to fire
off the spark.

To me, it sounds like you need to do more reading on how the ignition works and
what an MSD versus a standlone means.

 

I realize that if I take out the distributor, I will need to add an ECM of some kind as I assume the basic computer in the 7 wont do as much as I need it to. My query is on the need for multiple boxes is due to the prevention of lost spark on the trailing plugs. I can use one box on the primary plugs as lost spark doesn't have a detrimental effect on the rotors however lost spark in the trailing plugs can lead to damage due to ignition at off times.

Question make more sense now?

 

I think one false assumption your making is that the ECU on a 1st gen rx7 controls
the ignition directly in some way. It doesn't, so the ignition gets all its basic inputs
from the dizzy. You remove the dizzy you have to then substitute something in to
replace it and that would be a timing wheel and sensor with a standalone to
do the computations and fire the boxes.

Using 3 MSD boxes; one for leading and the other 2 for trailing is overkill for most
applications unless your going beyond stock rev ranges. Keeping the trailing ignition
is optional as well if your leading is a wasted spark ignition and very strong. See
my TFIDFIS thread linked in my sig.

Technically, you do need to either use the dizzy to split the firing signal to the
trailing or as your thinking use 2 separate boxes to fire the trailing. If you use
2 separate boxes you will have to use a computer to split the firing for one versus
the other I think on trailing.

I think your over thinking this a bit. Why do you think you need 3 boxes and why
do you think you need to get rid of the dizzy? I guess those answers would shed
more light on this.

 

No love for DLIDFIS?

 

Actually quite a bit. In my write up I even say what I've done is just a variation of
the original DLIDFIS you wrote about years ago. Standing on the shoulders of giants
and all that so to speak.

My slant was just to remove the use of the unobtanium ignitors and use some more
modern solid state coils. Otherwise the wiring is very similiar and I expect the output
to be fairly identical, although the HEIs can carry more power than the ignitors.

Jeff your contribution of DLIDFIS is a milestone in our community and inspiring.

 

Can someone spell out these acronyms? Good grief.

 

yeah I've always wondered wtf TFIDFIS and DLIDFIS stand for, also still trying to grow ***** big enough to attempt one of those mods.

 

The DFIS part refers to a Direct Fire Ignition System which means the plugs are fired
directly from the coils themselves bypassing the dizzy.

The lettets before the DFIS usually indicate the coil setup. DLI means something like
Dual Leading Ignition coils, 2GC - second generation rx7 coil, TFI - Ford TFI coil.

Note that all of the setups imply a wasted spark strategy whereby the leading plugs
are fired simultaneously everytime which results in a second plug firing for each
combutsion event.

 

TFIDFIS is technically DLIDFIS if it's wired the same. The ignitors and/or coils being from a different manufacturer shouldn't be a reason to rename. Don't you agree? It just further confuses people, as seen in this thread. Heck you didn't even spell DLIDFIS right in one of your sentences. What if someone tried to search and didn't get all the confusing letters just perfect?

 

Lol, I think the only way I'll ever understand how to install this, is if barney makes a write up

Thanks for the explanation, it does clear up things a bit.

 

Hmmm, I would agree except the I said the wiring is similiar and so its not the same.
Since its wired diffferently due to different ignitors and coils I think it deserved a
new name. Since I had seen the 2GCDFIS name, I figured I would just call it TFI
( for the coils being used) DFIS. Excuse me for not getting your approval on the
name of my ignition solution.

Its not like I've denied or not acknowledge your DLIDFIS contribution to this
community. I'm sorry your all butt hurt about it. I don't see you going
off on the 2GCDFIS when its mentioned like you have here when TFIDFIS is
mentioned?

All these different solutions achieve the same goal, a more robust and powerful
ignition spark for the rotary. The common thread is direct firing of the plugs from
the coil(s) bypassing the dizzy jump.

 

Congrats on getting all defensive.

 

 

R-cien,

pm me....I really have a write-up that is super easy to follow (cobbled together from a couple of other write ups)....it'll take you honestly, 25 minutes to install, and the cost of a 2nd gen coil will be your biggest expense.

Like I said before, I knew nothing, had no experience, and was confident I would screw it up beyond any repair,,,,finally took the plunge and couldn't believe how easy it was.

 

I would agree. Go for 2GCDFIS. It's fast, easy, and you don't need a bunch of shoddy Ford parts messing up your engine bay.

 

yes, same principle as DLIDFIS. so i could call mine MSDDFIS if i decided to use MSD coils. using 2nd gen coils made it 2GCDFIS.

 

Agreed...I have been trying to wrap my head around this mod for a while too (funny every time I read about it I'm drinking...correlation? Nah!)

I would love to attempt on at least one of the cars.

 

I did my direct-fire conversion a few weeks ago when my leading ignitor died during a heat wave. I used the two existing coils in the car (with an MSD6A that I got for cheap on eBay) for the leading spark plugs, and for the trailing spark plugs I bought one extra coil from RockAuto because I had to order stuff from there anyway. The longest part of the entire operation was figuring out where to mount the MSD box; otherwise, the mod is a piece of cake. Keep in mind that I had my FB for less than a month when I tried this, and it turned out fine. In the OP's case, he'd have the benefit of still being able to revert to the stock setup, unlike my situation.

Speaking of the OP, what up Minnesotan FB buddy :v

 

OP? Lol Lotsa good stuff here. So there is no way to eliminate the dizzy? How about if there was a sensor on the eccentric shaft reading the timing and sending that information to an ECM that controls the MSDs?

 

Thats usually referred to as a standalone. The dizzy provides timing pulses every 90
degrees of rotation and also takes care of advancing the ignition timing as rpms
increase. Without the dizzy you will need a computer (ECM) to count the pulses from
whatever signal mechanism you choose to put on the eccentric shaft (or you
could use the 2G CAS I guess also) translate that to a timing signal with advance
builtin to fire your MSD or ignitors or whatever.

So to answer your question, yeah you can do that but its not as easy as it sounds.
Although the MS solution seems to be a good way to go for that. A direct fire setup
is way easier and cheaper to do.

 

So the gen II have a DFIS? What is that system?

 

Second gens have a CAS and an ECU that controls fuel and spark.

Is it DFIS? I'm not sure, I guess it could be considered that maybe.

Not a 2G guy at all so I don't rightly know the exact answer.

 

Please do, I'm keen to have a crack in a few months with a few twists on what I can get in NZ