TFI Ignition Control Module w/stock points/distributor trigger

[Fred Winterburn]

Sorry, no schematics, because I build these for sale and put quite a bit of research into getting it right even with a good starting point from old Hyland units and lots of information left by my father. See capacitordischargeignition.com
I use a ferrite e-core as the basis for the transformer just like the old Hyland. The winding method is not for publication, nor are any of the enhancements to the rest of the circuit. If someone wants to buy one of my units, they can tear it apart and reverse engineer it if they really want to, but it wouldn't be worth doing since I doubt my price could be undercut anyway. If I ever wind up the hobby/business, I will post the schematic and the transformer/power supply particulars on the net and send anyone that bought one of my units, a circuit diagram. Fred


Any schematic for how you do your CDI setups? Sounds pretty nice. EI core or toroid transformer?[/quote]

[Lingwendil]

[GoMopar440]

It seems the TFI module will allow use of a coil that can exceed the stock VW distributor cap's voltage limitations. That got me thinking about using a different distributor with a larger cap. That would allow for a coil with a much higher voltage output, without getting the arcs crossing over to other terminals inside the cap.

I was thinking about something like this. It's listed on Amazon as a "Top Street Performance JM7650 VW Pro Series Pro-Billet Distributor with Red Cap"
http://www.amazon.com/dp/B00T9C8MGO/ref=dra_a_rv_m...a3e59e8a_S

It's a billet distributor with a large diameter cap, and the ad says it's for use with a 6AL (or CDI type box) with an external coil. There's also no mention about the type of advance mechanism, but from the photos it looks like it would most likely have a mechanical advance like the 009. The photos also show two wires exiting the body of the distributor. Details other than that tiny bit of info are pretty sparse. I'm not sure if it could be made to work with the TFI module or not. At $76.90 (w/free shipping) it's not exactly a cheap gamble, even if it is the least expensive large cap VW distributor I've seen anywhere. Does anyone here have any more details on this particular distributor?

If I do end up using a CDI, the one Fred Winterburn makes and posted about looks like a very well thought out option. I might not be able to afford one for a little while though, so I'm still planing to get the TFI module working with what I have for now.
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Link to my rail (re)build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=629493

[modok]

I don't feel there is a need to use large enough gaps to need a larger distributor cap UNLESS you want to get into very lean burn/high MPG tuning, or high powered CDI

There is debate over duration verses current. I've seen arguments both ways. Both that ONLY current matters or.... Longer duration is the way to go.
I tried quite a few coils, both extremes.
IMO, everyday use, I actually ended up at about the same balance as a blue coil, the 75 toyota coil has about the same "slope" on the scope, but much MORE, about 3x more energy. The TFI coil in comparison, was higher current, about same duration as the 75 toy coil, approx 4x more energy than blue coil.

I also tried a bosche coil that had VERY high amps, but I didn't note any improvement at all, past the first few seconds after startup. And a very LONG duration coil too.
I have noticed these high amp coils are more likely to have arcing problems, burn a hole through their insulators and cross-fire.

Voltage only peaks as high as needs to to establish a spark, so voltage is 90% controlled by your spark plugs.....not the coil.
But current is controlled by the coil..........well, coil and plug gap.

[Fred Winterburn]

I've found the voltage actually varies quite a bit, or more precisely the voltage overshoot beyond what certain plug gap should give. In addition to conditions within the combustion chamber that affect the voltage requirement, there is a voltage overshoot. The overshoot is considerably higher with a weak ignition system. Going to a higher turns ratio coil will most likely make the ignition weaker and result in a higher voltage overshoot prior to the gap breaking down. But yes, for the most part you control the peak voltage by adjusting the plug gap. It is possible to have a wider plug gap with a high energy inductive ignition with the same or lower voltage overshoot than with a weak inductive ignition and a narrower plug gap. Fred

'Voltage only peaks as high as needs to to establish a spark, so voltage is 90% controlled by your spark plugs.....not the coil.'

[Lingwendil]

Here's the module working. Barely lukewarm at idle, warm but not hot after a ~30 mile freeway trip. I removed the unused wire from the plug (which I sliced out of an econoline at the junkyard) and put some spade connectors on it. Working great with a points replacement module. It was misfiring with the points installed, but idles and revs like a whole new car.

It was zip tied in place temporarily, but I am going to make a aluminum bracket of some sort to mount it. I'm going to try and yank a module with the heatsink before I move on to New coils, as I'm running the stock Bosch 3 ohm right now.
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73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[Frank Bassman]

I did not realize you had duals. My mounting means would not have been possible for you.

And a general engine picture for good measure

Messy wires I know they'll be gone over soon.

I may try a toyota coil if the're so much more powerful than a blue.
Or a TFI.

Modok, what made you feel that a moderate as opposed to more extreme coil was better overall?

Frank

[modok]

To be honest the the TFi coil and toyota coil ran identical for practical purposes, only reason I went with the toyota was because it is 2 ohms rather than 0.7, so does not use the current limiting feature of the module.
\
The very high current bosche coil did not seem to cover over lean hickups as well, and the high voltage long duration coil was noticeably worse firing cold plugs, so, middle of the road seems to be where it's at for me. I did leave the plugs gapped at .035 and never changed that.

[Lingwendil]

My car is a 73, so I'm thinking of making a bracket to put it at the test connector location on the firewall, soon as I pull a module with a sink on it. This one runs fine but isn't easy to mount.



Also, is that black module working for you? I almost pulled one but was reading they wouldn't work, the econoline I grabbed my plug from had one on a heatsink that looked to be in good shape.
_________________
73 super beetle thread http://www.thesamba.com/vw/forum/viewtopic.php?t=649622 Back on the Road!

Modify your Kadrons for SVDA http://www.thesamba.com/vw/forum/viewtopic.php?p=8115884#8115884

Cast iron VJU4BR8 SVDA reference thread- https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Need replacement filters for original Kadron aircleaners? WIX #42087 is a perfect fit, as is Napa Gold #2087!

[Frank Bassman]

Modok, understood! Makes sense to make the current limiting work as little as possible to minimize stress on the module!

I'm now on the hunt for a coil similar to yours in characteristics. So you're at about 2 Ohm primary and what secondary? The closest thing I found is this...

http://www.summitracing.com/parts/acc-8140?seid=srese1&gclid=CIHK9NDOjMwCFQkfhgodwjMMqw

By the way, 0.035 is quite a large gap, I ASSume the motor runs great at that gap huh? Better response benefits from that?

About the black module, that was bought at auto zone once upon a time. I put it on recently just to see if it would perform better than the grey motorcraft from the junkyard... no difference. Just haven't gotten to replacing it again due to general laziness... same reason my wires are a jungle. It'll be done sooner than later though! Have to buy some electrical thermal conductivity paste to smear the back of it with the heatsink when I do though.

From what I understand the black OE modules work but don't have variable dwell. I don't know much though.

I was looking around for good canister coils that may work well (better/more powerful than the blue bosch), and I keep running into dead ends. Seems like most powerful canister coils don't last very long...

I first was going to get an MDS blaster but read of failures often and about 3 weeks ago I was working on someone's car with a blaster... and it was what blasted the engine's running.

I don't know much about accel but there's not much info out there as far as longevity. that coil I referenced earlier seems to not last.

I have been toying with ordering a Mallory... anyone have experiences with them? Specifically the canister ones like this one...

http://www.summitracing.com/parts/maa-29217?seid=srese1&gclid=CKfZ9IHRjMwCFUFehgodoPoEiw

I have honestly never had a problem with a blue bosch, but these questions are simply for the sake of experimentation. Wouldn't make much sense to buy any of these and not have a benefit over the bosch blue.

Why do I insist on canister? Looks honestly. I've try to steer away from alternative mounting situations other non canister coils may pose, including the TFI.

-Frank

[Lingwendil]

[raygreenwood]

[Lingwendil]

[modok]

More about the coil:
Autozone and o-riley are sold out of old toyota coils. Sorry too late. Autozone still lists a Wells c837, which does seem to be similar to the OE coil, but they are sold out. They have substituted c831, which seems to be a universal coil you can use on most any old car, but, it's not specifically for a 4 cylinder if the application also says it fits all old V8's too.

The way this stuff works these days, is to avoid drowning in dead inventory, when specific parts start to outlive the cars and demand falls the FLAPS drop the price WAY down, and sell as many as they can, and then maybe they keep just a few after that and mark the price WAY up. I think the sale on the toyota coils was missed by a few years, but there is still one NOS one on ebay for 40something, and you can get a wells c837 for about 15$, although frankly I don't have any idea if a wells coil is any good. The prices on old parts do not necessarily reflect the quality......at all, because of the way they make the prices whatever they want on old inventory.

The old toyota coil is supposed to have primary resistance somewhere between 1.5-2 ohms, secondary somewhere around 10k. The tolerances are quite loose on ohms you know. It will say "12v use with external resistor", which of course I ignore and overdrive it! Will any coil survive being overdriven at 2x it's intended current? probably not, but many do. It's probably not the smartest idea, but it's working fine.
The difference between a old v8 coil and one for a four cylinder will be how quickly it charges, which is a matter of the turns and core, which you can sometimes GUESS from the OHMs and feeling how heavy it is....roughly, tho may not be 100% accurate

A "universal" 1.5 ohm coil won't be hugely different, and may work very well too.
In the 80's toyota went to more powerful module, and coils with higher secondary resistance, around 15k ohms, for longer duration spark/bigger gaps.

I could be wrong, but seems to me VW went the opposite direction in the rabbit era, using lower secondary resistance. Not as large a surplus of those today, as I think a lot of them did eventually burn a hole through the insulator, maybe not it's won fault but they could do that, and they did.

Yes, check out wells C843 for cali emissions 1980 rabbit, secondary 3000 ohms,
that must have CRAZY high current! The C831 for normal emissions looks, more normal.....wait......they retrofitted a universal coil! ha! they tried to fool me

[Lingwendil]

[modok]

Yeah, the e-core does seem to be more efficient generally.
I did note some companies sell a, well not really a "E" but a modern looking coil like the one CB is using, for fitting to old toyota 20r apps. It comes with the ballast resistor. And thought......would it survive without the resistor? maybe not. Just looking at it, not much heat dissipating ability would be expected.

bosche did make a e-core 3 ohm and 1.5 ohm coils, it was called the GTsomething-T, and they don't anymore. heat might be an issue and that is why all the open core coils are usually 1 ohm or less.
Most of the E cores are LOW resistance primary and that's probably for good reason. The good news is the TFI can run low resistance coils, of course it's made to do that, and the TFI coil itself is a darn good example of one. Look up the plug gap they recommend for these, it is .040-.050 sometimes for the TFI models. I think .035 is very conservative, but, I don't want nor desire to push the limits of the small cap distributor.

autozone C899 is a round coil that from the specs looks like it would be really strong. For honduhs.

[raygreenwood]

The high voltage secondary coil from Bosh/rabbit you noted.....is the one I was speaking of. In the late 7ps/early to mid 80s......before NOX regulations got crazy....and mostly Non-cali....a lot of the golfs, jettas and sirocco ran high compression.

The early to middle years hall effect cars had listed in numerous places...55kv as coil voltage. I have also read other listings that noted 48 to 52kv.

Most of those high compression vehicles also listed the triple electrode Bosch or NGK.

Very nice set up. Ray

Edit: just looked in my book.

The golf/jetta/sirocco coil with points lists:
Primary circuit: 1.7 to 2.1 ohms
Secondary: 7000 to 12000 ohms.

The hall effect distributors (several variants)
Primary: 0.52 to 0.76 ohms
Secondary: 2400 to 3500 ohms

And
Primary: 0.60 to 0.80 ohms
Secondary: 6500 to 8600 ohms

[modok]

I think that WAS the high current coil I have and ran for awhile, but I didn't even attempt looking up it's part number, germans use too many digits.
It was the only coil I tested on the bench that would throw sparks clear around it's insulator if I accidentally unhooked the wire, like a tesla coil

[raygreenwood]

[miniman82]

I know this is about TFI, but if all you're doing is replacing the points as the current controlling device couldn't that be done much cheaper with a BIP style driver?


http://maya-auto.com/wp-content/uploads/bip373_datasheet.pdf


MS guys been using the VB921/BIP373 for years with no issues, seems it would cost less than $10 to throw together a simple circuit to run the coil and get infinite points life. Even if you wanted to go to a reluctor or optical style pickup, the additional circuits probable wouldn't go above $20 total. Just something to think about.
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Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747