Dyna coils

[bcknblkbird]

dyna coils

mr. england i'm getting ready to install dyna's on my xj, what size L brackets did you use ? thanks!!!

[natemoen]

I reject your reality and substitut my own!

[James England]

mr. england i'm getting ready to install dyna's on my xj, what size L brackets did you use ? thanks!!!

I bought four L shaped brackets from a hardware store... about 2" long each side. Each side had two holes. I used the top hole on one side (enlarging it slightly with a drill) to fit onto the frame and then cut half the other leg off with a hacksaw and enlarged the remaining hole slightly to take the allen bolt which I used to attach the coil to the bracket.

It sounds a bit involved but it took no more than 30 minutes to do the whole job and have the coils on a running. They were just basic DIY hardware store brackets, ready galvanised to avoid rust......

[DAVINCI]

I doubt if cherrypicking a few articles off the net will do it.

That's funny, isn't that what we do right here?

[cywelchjr]

That's funny, isn't that what we do right here?

Sure, but some of us know what we are talking about already and the "cherry picking" is based on our knowledge and to demonstrate what we are talking about.

Some of us have worked in electronics all of our adult lives (and sometimes even before then, working with projects before even high school), and use those articles as teaching aids, not to learn about it ourselves.

[DAVINCI]

As a footnote, I browsed the Dyna site and this subject is covered in their installation manuals. They talk about reduced performance when polarity is reversed, but doing so will not damage the coil.

[natemoen]

Oh come now children, play nice

[DAVINCI]

I swear it's true...........i read it on the internet!

[James England]

As a footnote, I browsed the Dyna site and this subject is covered in their installation manuals. They talk about reduced performance when polarity is reversed, but doing so will not damage the coil.

That's the single output coils, one assumes? The polarity isn't marked at all on my dual output ones.

[crazy steve]

As a footnote, I browsed the Dyna site and this subject is covered in their installation manuals. They talk about reduced performance when polarity is reversed, but doing so will not damage the coil.

Short term reversal won't immediately burn one up; any coil will operate for at least a little while. Depending on it's internal constuction, one may last quite a while. Construction/insulation methods have probably improved over the years, so this may be less of an issue now, but it's still an issue. If the coil is switched electronically, I suspect that the electronics would fail before the coil. One of the issues with reverse polarity on points ignitions was badly reduced points life.

The interesting part of this is the loss of output, and how it relates to our XS twin-tower coils. In a single tower coil, part of the reason for the loss is the circuit path through the primary coil if the primary polarity is backwards, but in even a no-polarity twin tower you'll have some of this loss at one of the two plugs that are fired. In most cases, this will go unnoticed or is factored into the design. If you look at most late-model cars that have distributorless ignitions, it's pretty typical to find one coil per pair of cylinders. Same operation as the XS; every 180 degrees, you have one cylinder fired and one 'wasted' spark. But many of your higher-performance models feature 'coil on plug' ignitions (think late GM LS motors among others), with a single coil per cylinder. This is done to eliminate polarity losses and insure equal spark to each cylinder.

So that begs the question; is there a performance improvement to be had by using individual coils on a XS? I'm sure there is, but it would probably be small. Besides the difficulty of figuring out where to put four coils, you also have the problem of 'will the TCI be able to switch the current of two coils'? If you used two 1.5 ohm coils with the primarys connected in series in place of each stock coil, the answer is yes, but now the issue is what is your secondary output? You've cut the primary voltage in half, so to maintain the secondary voltage high enough you would need a different turns ratio in the coil. This in turn would reduce the secondary current, giving you a bit 'colder' spark.

Anyway, just food for thought...

James, nice install on the coils by the way...

[James England]

James, nice install on the coils by the way...

Thanks! It's surprisingly easy to do and those Dyna coils are just so compact. They fit with hardly any effort at all and are smaller than the OEM ones......... working well so far too!