Bosch Electronic Coil

[Tham]

I found this Bosch coil at the salvage yard where
I had bought the Nippondenso electronic
distributor earlier for my Corolla's 4K.

It's marked "For Transistor Ignition" and
must have been salvaged from a BMW. It has
part No. 0 221 118 335 carved at the bottom.

Is this the same as the Bosch "black" electronic coil
mentioned in the other posts here, and could it be
used with the 4K's Nippondenso electronic distributor ?

I measured it, and the coil's primary winding has
a very low resistance of just about 0.6 ohms (versus
1.5 ohms or more for typical Japanese electronic
coils.

Secondary resistance is equally low, at 6.3 kohms,
versus typically 10 to 12 kohms for Japanese coils.

Wonder if it might burn out my igniter. The salvage
yard owner said it was meant to be used with BMWs',
Audis' and Mercedes Benzes' electronic systems.


http://market.autopartsfair.com/bmw-...tem-44655.html

[o_man_ra23]

Find out exactly what the resistances normally matched to your ignitor are. At 0.6 ohm compared to 1.5 ohm, you will draw about 2.5 times the current from the circuit. The ignitor may support this with a drastically oversized IC, but more than likely you will burn the circuit to a crisp. As it is called in the industry... a smoke emitting device

Just go and grab the bosch catalogue and get the recommended GT40 coil.

Cheers, Owen

[Tham]

Thanks for the info. Wow, luckily I didn't try
out this coil earlier, or else I would have fried
my ignitor.

I'll try out the Hanshin Japanese electronic coil
which the salvage yard gave me initially, and
check out the Bosch GT40 too.

[oldcorollas]

orange bosch GT40 = bad for electronic ignition... why not jst get a replacement black Bosch coil for electronic ignition?

[Tham]

why not jst get a replacement black
Bosch coil for electronic ignition?

Oldcorollas, is the above one which I have
the same black Bosch coil ?

http://market.autopartsfair.com/bmw-...tem-44655.html

[oldcorollas]

i was thinking more about the transformer style...

the GT40 are known to have issues with electronic ignition but..

http://apps.bosch.com.au/motorsport/...itioncoils.pdf

like type A here....
you may just need to run a ballast resistor with it... (the one you have now).. ie, a 1ohm ballast...

but either a transformer type or an oil filled type will work... i suppose you should match your ignition coil with your ignitor.. so in this case, a ballast should be ok...

[o_man_ra23]

i was thinking more about the transformer style...

Actually Stu, all coils can be classed as "transformer style"
Transformers can be purchased dry, oil filled, or resin filled. The latter is the style you make reference to. But the way that coils are wound is identical to how tranformers are wound. In short, coils are wound transformers which are specifically designed to operate with spikes rather than a wave form, and are to ramp up from 12V(ish) up to 32,000+ volts. (hence why the GT40 is known to fry ignitors, it outputs the same current, but outputs an extra 8,000ish volts, and so the input current must be higher, as the input voltage does not change).

Cheers, Owen

[oldcorollas]

ahh, i'm just using Bosch terminology
ie, the ones that look like transformers instead of a standard "coil" (back when they were new and oil filled were normal)

i thought the GT40 are known to fry themselves when used with higher dwell??? particularly with the high dwell of the jaycar HEI... definitely didn't kill my HEI

then again, the jaycar thing has current limiting (of sorts).. so that helps... hmmm

[MWP]

then again, the jaycar thing has current limiting (of sorts).. so that helps... hmmm

The Jaycar HEI learns what dwell is required to fully charge the coil from previous firings.
In theory it should never fry a coil.

A low resistance could fry the HEI though due to extra heat dissipation in the HEI's output transistor which could then toast it.

[oldcorollas]

really? i thought it had a fixed spark length, and the rest of the time was dwell.. and current limiting was what stopped the coil from burning out due to oversaturation?

not that i'm an electronics kiddy

hmm.. but current thru the output transistor is limited by the current limiting circuit.... so there is only so much power that is able to go thru it...
perhaps i had my current limiting a little lower than most?

[o_man_ra23]

Anything is possible. The GT40R will fry when run with electronic ignition without a ballast resistor as its designed for use with a ballast resistor. GT40RT being the resin filled "transformer style" version. Oh yeah, id like to see a transformer which looks like one of those, they physically look nothing like any transformer ive come across, the can type looks closer to the mark, though most trannys look like a box. Maybe Bosch is talking about shitty little transformers used for cheap kids toys (trannys are outdated, and anything small which use them are cheap crap, switch mode power supplies are far better).

Anyways, Bosch make a series of GT40 coil specifically for electronic igniton vehicles (think foulcan and commonwhores of the early/mid 80s). These are ones which specify use without a ballast resistor, and with an electronic ignition module.

Cheers, Owen

[oldcorollas]

they'd be the black ones right?
the orange GT40 something.. resin filled funny looking transformer thingy... is the one i killed in abotu a week with the HEI.. and the one silicon chip printed an errate about not long after the first article...

[o_man_ra23]

GT40 coil is avail in resin filled or oil filled can style. I was running an old can style orange GT40 coil, pulled from a 250X-flo foulcan when i was working at a fraud wrecker, with my Jaycar HEI ignition and never stuffed the coil. I later changed to toyota 21RC ignitor, and continued using the GT40 coil till i pulled the motor and sold it to Norbie. Coil stayed with me till i moved to Mackay. Perhaps you were using the style meant for use with a resistor?? Or another funny variant??

Cheers, Owen

[MWP]

really? i thought it had a fixed spark length, and the rest of the time was dwell.. and current limiting was what stopped the coil from burning out due to oversaturation?

Actually the dwell is controlled by the spark time.

Ie, the coil is turned off to spark then left off until the HEI thinks its time to start charging so the coil is just fully charged for the next spark.