TomaSoft

Here is my DFI setup:
I rebuilt the distributor to get one signal for each spark by duplicating nearly everything inside.
Now I can use one individual coil for each spark.
I use 4 original transistors.
The shaft is 100% locked.

As I'm not an expert in ignition I have some questions:

The coils:
I'm actually using original first generation coils.
Should I use some other (better?) coils e.g. MSD Blaster 2 or similar.
I don't want do discuss here/again which one is the best, but I just want to know if it's worth changing from original to another one.
Is it worth to change all the coils or only the two leading coils?
Don’t forget, that the coils and transistors only have to do half of the work, they did before.

Combining L1 & L2
Due to this setup, I have the opportunity to combine individually L1 and L2 for triple ignition sequence (L, T, L) per combustion.
Is it worth doing this?
I also have the possibility to combine L1 & L2 only till the engine reaches certain rpm and than return to single L ignition for high rpm to avoid firing the L spark too late at second L-fire or too often at very high rpm.
Is it worth doing this?

I know, a lot of questions, some stupid ones maybe, but as I already mentioned I’m not an expert in this case, so that’s why I ask.

Maybe important:
The actual engine that I’m using is a bridge ported 12A.
Why I did this? Because it's possible and low budget

If I missed something, please let me know.

I’ll attach some pictures of the previous version this evening (they are on my PC at home) as I have made no pictures of the actual version yet.
The running version is nearly the same except for the magnets. I now use only 2 of them. I think that the pulse with 4 magnets (2 in parallel) is too high, as my transistors broke after a couple of minutes in several tests.
If you are not sure what I built, please wait for the pictures, they’ll explain everything.

TomaSoft

So, here are some pictures of the first version, with 4 magnets.
Please notice that with this setup worked, but it killed the transistors after running a couple of minutes.

TomaSoft

Some more pictures from a different angle.

TomaSoft

Some details.

TomaSoft

Finally some pictures of the only thing that changed in version 2.
These are the only pictures that I made, as I got a little bit under deadline pressure for the next race.
I'll make and post some pictures of the finished V2 already on my autocross car.

TomaSoft

Here some pictures of the DFI4 V2 in the car.

Some more pictures:
http://www.facebook.com/album.php?ai...&id=1240055542
http://www.facebook.com/album.php?ai...&id=1240055542

TomaSoft

More than 100 views and still no answer.
Are my questions so stupid?

RotaryBred

yes, it's always worth upgrading to higher output coils (i use MSD blaster SS since they look great and mount flat)... i'm not too keen on DFI since i'm an EFI guy, but i understand you concerns with firing the L2 too late since you have a bridgeported block (assuming you run at very high RPMs), but i have never heard of anyone doing this before and i think you will run into timing issues when the transition is made. hope that helps you, but please look for second opinions, like i said I'm no DFI expert LoL

GORacing

No, not stupid at all, just not sure were to start... so... What is the goal? power, accuracy, reliablity, just an engineering exercise??
coils - you stayed with stock coils, so not much of an increase in overall sparking power... yes, dwell (saturation), time is a little longer so high rpm output will be a little better, but with this also comes more internal heat build-up, which factors into reducing reliability... so as Rotarybred suggests, upgrading the coils is a plus, not the cheapy upgrade coils (designed for higher output at low RPM but fail quickly when asked to operate at higher revs), but the higher cost units that are designed for sustained high RPM use is what will give the best results. You ask about doing this to the leadings only, sure you can go that route, as they are your main ign, and you stated you would be killing the trailing at high rpm anyway, so, sounds good so far...

A little fuzzy on what you are asking about with you "triple ignition sequencing"... what you are discribing is a basic wasted spark system sequence as used on a 2nd or 3 gen RX-7, you are just using two single-output coils instead of a single dual-output coil, no problem doing this on the leading ign only, the wasted spark is firing at relativly the same point in rotation at 2000 as it will at 9000 RPM, in a dead zone, check you timing at both leading plugs at high revs to check for ign timing drift, if they drift at all, then your ignitors are not fast enough an you will need to go to individual firing mode, to minimize drift have as short a spark plug leads as you can and both the same length, and try closing the spark plug gap down a little... oh and is it worth going wasted spark... generally is easier to do but with a slight lose of overall power output...

definately only use two pickups, especially in this configuation as they do not need amplifing, you can wire the other two through a switch as a backup since you have them, did you use an o-scope to check output wave form to make sure you are not getting stray signals?

BIG NOTE : some thing I noticed missing on other direct fire related postings, be real carful with the unshielded trigger wires especially around the alt and coils, roque signals are easily generated around these areas unless shielded and will cause crossed or inaccurate coil firing which will distroy the engine at high speeds
hope this gives you something to work with...

TomaSoft

First of all: Thanks for you answer.

I was/am no sure if other coils are really better than the original ones.
I read some treads and could not really get a proper pro or a reliable contra to my question, as allot of people said that the original ones are good enough and some swear on other ones.
My main question to this point was: what does that mean good enough? Just good enough or you can’t do better?
Are for example, the MSD blasters better than good enough?
As they are not really expensive I thought changing for those ones.

As I already mentioned my coils only have half the work to do compared to the original ones. Except for the Leadings if I go to wasted spark system. (Combine L1 and L2)
That's why I only wanted to change the leading coils.

And yes considering the L1 & L2 fired together, my main concern is to fire the L spark too late at high rpm, as my ignition is 100% locked. That’s why I think I should, if combining them is good at low RPM, separate them for high or very high RPM.

TomaSoft

Thanks for your answers too. Hell allot to read, same as my questions I guess

I want it all. (If possible)
I did this, because I thought that it is useful to control the L1 & L2 combination, e.g. switch it off at a certain RPM range.

Just to be sure, my system is well understood.
I’m not killing the Trailing coils away at high RPM, just the L1 & L2 combination (wasted spark system) to be sure not to fire the L sparks too late at second L fire.

As I want to use the wasted spark system only for low RPM, do I really need the higher cost units that Rotarybred suggests?
If my system runs normal (L1 & L2 not combined), my coils do only half of the work that the originals do.

We tested the engine with an original ignition and it made 10’500 RPM like nothing.
As we finished the car only the evening before the race, I had no time to do more test.
When I installed the DFI4, we had no more time left for testing and I didn’t realize that my instrument shows only half of the real RPMs on race day. I’ll solve this problem for the next race. You can not think about everything!

Yes that’s what I meant.

This is what I’ll do:
That’s a good way to find the point where my ignition needs to go to single mode.
I’m just not sure about the spark plugs, do they work well at 7000 RPM which would mean 14000 with L1 & L2 combination?

I need these 4 pickups for my system, as I cut some part away from the ignition 'rotors', to separate L1 & T1 from L2 and T2!
See picture below.

As my trigger wires come close enough to the alternator and the coils, I also think it’s better to shield them, just for sure.
I’ll test the signal with an oscilloscope if I’ll find the time some day.

RotaryBred

i don't have time to read everything here since i'm on my way out.. but the blaster coils are awesome coils, and i only payed $40 a piece for them on ebay. i can jump a 1-1/4 inch gap just running them off of the igniter without my 6A. With the 6A the spark is jumps about the same gap but is about 100 times larger and brighter.

TomaSoft

Thanks for the info.
I'll buy 2 of them for the leading ignition, so that I can test them in the next race.
I found them for 38.30USD at e-bay.com. Just have to check the shipping fees to Luxembourg in Europe.

TomaSoft

Update!

I realized yesterday, that on the pictures above, the ignition cables are not connected correctly.
I removed the spark plugs after the race, to check them.
For the pictures, I reconnected the wires to plugs no matter whether it is correct or not. No time to think about it

Here are the correct pictures, to prevent wrong information in this treat.

TomaSoft

Any suggestions?

TomaSoft

I'll start to build the DFI4 V3 today.

History:

V1:
4 magnets, 4 inductors, 4 transistors & 4 coils. 100% Locked
The transistors failed after a couple of minutes.

V2:
2 magnets, 4 inductors, 4 transistors & 4 coils. 100% Locked.
Worked well in its first 4 hour endurance race.

V3:
2 magnets, 4 inductors, 4 transistors & 4 coils. Mechanical advance.
Hope to get more power at low RPM range.

I'll keep you informed

TomaSoft

Just finished the DFI4 V3 today.

Here some pictures.

If you want more you'll find them here http://www.facebook.com/album.php?ai...0055542&ref=mf

TomaSoft

The finished product.

I'll post some more pictures when it's in the car.

TomaSoft

Update.
DFI4 V4 (Same as V3 with some minor mechanical mods.)
.
The ignitors are located inside the car.
.
The car in action: http://www.youtube.com/watch?v=eFB1T5QsIcY