I am setting my car up with 2 MSD E core (blaster SS coils) on the leading in the direct fire arrangement and not run the trailing at all. (TFIDFIS)


With that set up, is the ignition set up still an inductive system? Just with direct fire wasted spark.


Do I have to run the 6a to be a real CDI? (Capacitive Discharge Ignition).

Is there any real benefit to using the HEI ignitors vs. J109's except for availability? (I have quite a few J109's laying around). I am curious if the HEI ignitors actually transfer more energy than the J109 ignitors?

 

Direct fire using a msd box versus factory/gm/igniters have the same result. HOwever, MSD box offers a more precise spark per my observation.

 

DLIDFIS using J-109s and stock Diamond coils works fine. You won't even need trailing, but it's easy to keep (I understand you have an old school and probably lack the space or desire to add a third coil).

 

HEI vs J109, the HEI can handle more current, so can deliver a hotter spark. They also are more
reliable and easier to replace if you are out on the road.

 

Has anyone found a source for the cheap-o Chinese J109 knock-offs? I can only find dealers that have minimum orders of 200.

 

thats correct, the stock system is inductive, no matter how many coils you have.

to get CDI, you need a capacitor... MSD, etc

Mazda has graphs of CDI being better on the racing engines, but then the 787B looks inductive, and the street cars have always been inductive.

 

I am dating on keeping the J109s mainly for the clean look of not having the huge HEI ignitors with a heat sink as well. Another reason why I don't really want to use a 6al, but I am using the MSD SS coils which are pretty much made to run with the 6al...

But this 12a will be Weber IDA blow-through turbo , and I need a good strong spark.

 

Screw it... I am going with the HEI igniters and no 6al. I don't like the idea of splitting the 6al between two coils and I don't want to run two of them.

If I am blowing out my spark or fouling plugs, I'll add it then...

 

If I mount the HEI igniters underneath my dash inside the car, do I still need a real deal heat sink and heat sink paste? Or can I just mount them on an aluminum plate?

Underneath my dash is almost completely empty. There are very few wires, no ac/heat duscting, ect.

 

They need an aluminum plate and some heat sink goo every time. Think of them like a CPU in your home PC that's been overclocked. You can mount them wherever you want, but if you get misfires it means the pickup wires are getting RFI (radio frequency interference) or electrical interference. Then you wrap the wires in aluminum tape and ground only one side.

The only part of your project I disagree with is the boosted IDA. Oh and I kinda disagree with not running trailing, but a weber might not run well enough to take advantage of trailing anyway, so maybe no trailing is a good thing here - might prevent a popped engine.

 

I realize my choice of a blow-through IDA is a rough one. It was more of a, I have the parts so why not choice. It's a buffer to keep me happy while I am building the real motor for the Rx2. Which is a PP Renesis on slide throttles and Semi-Direct injection. That's taking longer than an expected, so a little boosted weber is fun to play with while I figure my PP motor.

As for wrapping the pickup wires in aluminum tape, do you mean something like HVAC tape? And I would ground one side of the aluminum tape?

 

You don't need a fancy heat sink, just some bare metal to mount them to so the
heat can dissipate out to the surrounding metal they get bolted to. Also make sure
to use the paste, its what conducts most of the heat efficiently to the mounting plate.

I would worry about the distance that the weak dizzy signal has to travel mounted
that far away. You want them as close to the dizzy as possible to avoid cross talk
and signal dissipation.

 

Here you go








Mazda RX7 Forum - 1st Generation RX7's • View topic - wasted spark and direct fire on leading plugs

 

Holy Over Engineered Batman! Looks well done and with a small fan to boot.

From experience, these ignitors don't get that warm but kudos for a nice job.

 

When I get everything in the mail on Tuesday, I will see if I can mount the HEI igniters under the SS coils. Which will hopefully fit above the leading plugs in the trailing plug area. This way I can hide the ignitors and still keep everything close with minimal wiring.