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Author: Subject: CDI ignition... here 'tis
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posted on July 22nd, 2003 at 01:07 AM
CDI ignition... here 'tis


when i had mine hooked up, and sisabled the MSD bit it started so smoothly (stone cold) it was scary. just have to play with the timing and locate it somewhere in the airflow to keep the bugger cool.
also want to team it up with a 'pointless' ignition one day soon, if anyone has any comments on what's worked for them.

http://www.dse.com.au/cgi-bin/dse.storefront/3f1c001208f81f50273fc0a87f9c0654...

hope the link works :D




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posted on July 22nd, 2003 at 12:46 PM


It would wanna be good for $148!!
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posted on July 22nd, 2003 at 01:02 PM


The link takes you to the Dick Smith front page. Just click Advanced Search and type in 'CDI Ignition', or click here :thumb



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posted on July 22nd, 2003 at 01:14 PM


Has anyone tried the Jaycar "Universal High Energy Ignition Kit"?

http://www1.jaycar.com.au/productView.asp?ID=KC5247&CATID=&keywords=i...

There is not enough info. at the web site to determine what approach it uses, but at $53 it might be worth knowing.




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posted on July 22nd, 2003 at 01:22 PM


Forgive my ignorance, but isn't that all build into the bolt in electronic ignition kits?? (that replace the points)
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posted on July 22nd, 2003 at 01:40 PM


No, generally the points-replacement kits do just that - replace the points.

The CDI and High Energy Ignition kits are designed to extend and amplify the spark, and are still triggered by whatever you have installed in the distributor. :)




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posted on July 22nd, 2003 at 01:48 PM
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Why did you disconnect the MSD bit?



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posted on July 22nd, 2003 at 01:57 PM


Quote:
The CDI and High Energy Ignition kits are designed to extend and amplify the spark, and are still triggered by whatever you have installed in the distributor. :)

Wouldn't that accelerate burning out of the points ?
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shocked.gif posted on July 22nd, 2003 at 02:59 PM
Has anyone tried the Jaycar Kit...??


NO! there is so little current going thru the points they will NEVER burn out... Only the plastic bit that rubs on the shaft will eventually wear down.... when it does... just adjust the points again and away You go for another 20,000kms or whatever (that was a wild guess)..
:thumb:thumb:thumb Sound great to Me..
Has anyone tried the Jaycar Kit??
That sounds OK and and $55-00 a bit better priced... although the circuit diagram goes back to 1998.... a long time in Electronics....
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posted on July 22nd, 2003 at 04:35 PM


I have tried the Jaycar kit but had problems that appeared to be related to the coil overheating (it was a new standard coil, not a high power one). Basically, the symptoms were that the engine would start misfiring and eventually stop running. It was a bit difficult to test fixes because it took hours of constant driving before the problem occurred. Mind you I think the kombi coil location (bolted to the engine) is not the best for heat shedding.

I decided that the circuit was probably designed for an ignition with a ballast resistor and so went back to the standard ignition. Same coil - lots of driving - no problems.

That said, other people on this forum have used this kit with no problems at all!
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posted on July 22nd, 2003 at 08:52 PM
cruddy links


the kit no. is k3307
seems there's no shortcut to get to the page it's on huh kombi.. thanks, DSE.

anyway, i disabled the MSD thing, cause i figure one spark is all you need to ignite the mix, and my dub wasn't happy with the MSD bit of the circuit. it took a whole resistor to do the disabling. the instructions for the kit were a bit ambiguous in relation to what kind of trigger circuitry you were running, (points, reluctor, hall effect or whatever) which was annoying, but several improvements were made over previous CDI ignition systems, hence the pricetag. Somewhere here i have a bunch of notes..
umm
yeah it's sposed to save your points, since the spark doesn't actually jump thru the rotor like it does with the high current style points/coil ignition system and lead to arcing and that annoying nipple on the contact point. how i managed to put 'annoying' and 'nipple' and 'contact' in the same sentence is beyond me.

but yes it is expensive, i'm just lucky to have been given it as a gift. several years ago when it was cheaper. but hey, it gives a HELL of a spark.kkkzzzzxxxt
it's not a longer-lasting spark, but it's a longer-throwing spark and a bright blue/white one, instead of the cruddy yellow/orange one it replaces. it also has the advantage of sparking at high rpms with no loss of spark energy, unlike conventional systems. just have to keep the bugger cool and preferably in the airflow, as the components don't like high temps. big case, no room in engine compartment. the case they're mounted in acts as a heatsink, but i might put some more fins on it next to the mosfets. first i'll see if it dies under the back seat like the rats that used to live there. or were they possums. by the state of decay i found them in they were dead. and possibly rodents. i'll have a squiz for the site with the blurb. brb




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posted on July 22nd, 2003 at 09:59 PM


In answer to some earlier questions, the Jaycar Kit is fairly similar to what is in the better "pointless" ignitions, but has a higher current capability - hence can drive a lower coil resisntance. It also has a "refire" function to try to re-ignite the spark if it goes out. As to it's age, it's actually a re-vamp of an old ETI design from about 1984! Finally, as the average current through the coil is greater with any dwell-extending ignition, it will run hotter.
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sad.gif posted on July 22nd, 2003 at 11:25 PM
read all about it.. if you can get the site up...


the DSE kit (expensive one..) is a complete redesign from the ground up and is an attempt to address the issues with previous capacitor ignition kits. i have been surfing google for ages trying to find the info i found yesterday by accident. it's in PDF format and i can't get it up and displaying again, so try this if you're interested :
direct cutnpaste from the site i know it's at. good luck.
also this was designed in 1997, which may seem old, but it's not like a beta version, it's a whole new crazy ball of fun.

[PDF]Multi-Spark CDI
File Format: PDF/Adobe Acrobat - View as HTML
... and thereby can de-liver unwanted sparks in other cylinders ... A new CDI design had to
be a distinct improvement over the 20-year old designs which did ...
http://www.thecarricos.com/ACRE/Documents/  Cap-dis-ignit-CDI.pdf - Similar pages

Tech Page

wow. that whole search was truly exhausting. HOWEVER in the process i came across many bizarre first hand accounts of the CDI kit's worth. everything from drag racing to motorbikes to rovers, bad stuff: cross fire in ignition leads (easily remedied) and short duration spark (hence the multi-spark function, which mimics the longer dwell of an ordinary one) also the serious speed of the spark means you need to retard the timing. just how much.... i'm working that out i hope.
for the few seconds i ran it at idle i was impressed, then the driving around bit showed the need for retarding. just gotta get into the tune up.
a dyno and a programmable advance curve box (jaycar) and a pointless ignition(all over the place) would be on my wishlist....
well. I'm toast.:jesus




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posted on July 23rd, 2003 at 12:04 AM


Hmmm, you read all that, so why did you disable the multi-spark function? You shouldn't need to retard your timing to run a CDI, unless it was advanced in the past to cope with a poor burn. CDI is known for it's ability to ignite just about any mixture under high swirl. Also, the short rise-time of the spark may cause problems with some coils - notably non-oil filled copies (of more expensive c-cored designs.) And it will tend to show up problems with any old coil...

For anyone following this thread, we should mention that cross-fire is usually cured simply by separating the leads... And that the expensive "pure copper" suppression leads, if they are still sold, will cause major dramas (they had a coiled wire in them.)

I'm not sure what your comments about the "pointless" ignition mean - maybe you are referring to the fact that the cheap ones tend to produce different timing on each cylinder? They will work just fine with the DSE kit [sic] (actually a Silicon Chip design,) but a set of Bosch points (with the appropriate grease) should last the life of your car with this design anyway.
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posted on July 23rd, 2003 at 01:07 AM
CDI ignition kits ??


Well, thanks for all the information folks,
made very interesting reading... I know Jaycar say in their catalogue "thousands sold" so they can't be that bad.. Maybe with a new oil filled Bosch coil... or Bosch C core Coil - sitting on the firewall, to catch some nice cool air.... I know the ready made units always have a built in heatsink to help keep them cool..
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posted on July 23rd, 2003 at 07:16 AM


I use an old version of this type of ignition with a bosch GT40 coil. I think it makes a moderate difference. Like has been said, points last for ever. Mine has a gr8 function that lets it go from electronic to points switched ignition at the flick of a switch. A light on the front of the unit for static timing too. Next plugs will be '40 thou gapped to take advantage of the big phat spark. I know how much more kick the gt40 gives as it got me a good one on the back of the hand when playing with the points one day- talk about woke me up! I could feel every joint and muscle from there to my knee where it earthed back to the towbar :bounce yeeeow!

Can do pics if anyone interested.

kkk
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posted on July 23rd, 2003 at 08:27 AM


This is a 'Bob Hoover' sermon I was emailed about CDI fwiw




Electronic Ignition for the VW
The Kettering ignition system of points, condenser and coil was never more than a compromise. (The Model T, with one coil per cylinder was more dependable, but also more complex and costly.) The component most likely to fail in the Kettering system was the points, since they had to carry up to ten amps of current, a difficult task for any switch turned on and off fifty times per second. Until they found something better, Detroit designed their way around the problem with dual points and even dual ignition systems. The cure wasn't found until the advent of the transistor in 1948, and didn't gain commercial popularity for another twenty years.
The cure for the Kettering system is to use the points not as a current-carrying switch but merely as a signaling device to tell the ignition system when to fire the spark. The actually switching is done with a solid state device called an SCR (silicon controlled-rectifier), a specialized form of transistor.

And instead of feeding the coil a diet of 12 volt current, it is fed 400 volts, allowing it to build up the maximum charge in the shortest time. The 400 volt energy is developed using a tiny switching transformer inside the ignition module, the energy stored in a large capacitor which is discharged into the coil at the appropriate time. This capacitance-discharge gave such systems their name, often abbreviated to CD.

'Point-switched' CD ignition systems require periodic maintenance as the rubbing block wore down, typically about every 10,000 miles. The points required replacement at about 50,000 miles, due to rubbing block wear. The points themselves are still in perfect condition at that time. Designed to switch a 120 watt load fifty times per second, they hardly notice the microampere load needed to signal the CD module.

The biggest advantage in CD ignition is improved efficiency. Spark voltage remains constant at all speeds, and constantly high. With a dependable 40,000 volt spark at all engine speeds the spark plugs may be gapped much wider, providing better flame- front ignition. The wider plug gap fouls less readily, giving even worn engines a boost in efficiency. With electronic ignition regular sparking plugs last about 25,000 miles, the new platinum jobbies up to 120,000. Over all, CD ignition insures better combustion, resulting in better fuel efficiency and lower emissions. The engine even runs cooler, thanks to less after- burning in the exhaust manifolds.

A point-switched CD ignition module is the wisest ignition modification you can make to an early VW since it supplants rather than replaces any of the stock ignition components. Indeed, should the electronic module fail you may return to the stock Kettering ignition by simply reversing a plug on the ignition module. Such redundancy is lacking on all modern electronic ignition systems, a potentially fatal flaw since they give no warning of incipient failure.

The most practical CD ignition module for Volkswagens was available from J. C. Whitney until March of 1995 (although it was never advertised specifically for VW's). Cost was about $50 and installation took thirty minutes for a clumsy mechanic with few tools and no electrical background. J. C. Whitney's current 'VW- specific' CD offerings cost about $100 and requires replacement of the distributor. This newer system, and all others presently offered by J.C.Whitney, uses optical triggering. Properly installed, such systems need no adjustment for the life of the distributor, about 70,000 miles in most cases. But as with all optical or magnetically triggered systems, you cannot revert to Kettering ignition without re-installing a set of points or replacing the entire distributor.

As to the dependability of such aftermarket CD modules, I have installed well over 100 (possibly twice that) with but a single failure, and that one was bad out of the box (and promptly replaced by the manufacturer).

I've used CD ignition modules since 1961, building the first few. (I am a ham radio operator.) I have more than 20 years experience with one unit: I installed a CD module on my 1973 Datsun the week it was purchased (new). The Datsun has accumulated 230,000 (on two only two engines). All of my VW's (four) are fitted with CD ignition although none have accumulated as many miles as the Datsun.
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posted on July 23rd, 2003 at 06:13 PM


Very interesting read

I've been contenplating this for a while, and never got around to trying one of the kit's. From the reviews it sounds like it's worth a go.

What version(s) of CDI have you got Koolkarmakombi?

Anyone recommend the Dick Smith one over the Jaycar?

Time to check out all those links :)

Cheers
Jeremy :thumb




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posted on July 24th, 2003 at 12:07 AM


The Jaycar Kit mentioned here isn't a CDI.
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posted on July 24th, 2003 at 08:22 AM


Hmmm.....
I'm a little sceptical on the cooler running claim.
Does anyone have any hard evidence with all this better running, better burning, more power, more efficiency on what it does to head temps??
More power means more energy from some where, and if that needs to be dissipated by the heads they will run hotter.
I understand what 'bob hoover' says that if there is less to be burnt in the exhaust, but wouldn't that lower the exhaust temp at the expense of the heads??
Just curious.
Great reading though!!
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posted on July 24th, 2003 at 02:22 PM


this is the one I use

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posted on July 24th, 2003 at 02:23 PM


front, yellow light is a static timing light.
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posted on July 24th, 2003 at 02:51 PM


front of the unit, yellow static timing and switch from points loaded or unit loaded. Seems to carry a constant dwell of about 80deg. Starting is much more prompt with this unit. I believe that the unit gets more effective as the revs go up, or for highway miles as the coil throws a bigger spark more consistantly up the rev range. I cant say I have noticed a temp change as ive changed other variables like the oil and filter

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posted on July 24th, 2003 at 03:00 PM


1600 cc of kombi pushing power....be afraid.....

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posted on July 24th, 2003 at 05:28 PM


Quote:
Originally posted by 70AutoStik
The Jaycar Kit mentioned here isn't a CDI.


Now that you mention it there is no mention of CDI at all in any of Jaycars blurbs.... mention, mention (Argh too many mentions.... :)

KoolKarmaKombi, cheers for the pic's - from your post above I was expecting a photo of you hanging onto your coil with your hair standing on end...... :D

Talking of cross firing, etc, a thought that may want to be considered is the size of the VW Dizzy cap... What are the chances of high currents going astray in here, causing misfiring?

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thumbup.gif posted on July 27th, 2003 at 01:43 AM
K3303 DSE Hi Energy Ignition Kit


I have the latest High Energy Electronic ignition kit from DSE and they NOW specify.. Not to Use a sports coil like the Bosch GT40 etc... as they will Use More Current and they WILL Overheat.... a standard ignition coil Must be used. Once My Son assembles it for Me, and I have it installed in My 68AutoBug, I'll let You know how it goes.... the design and components have been upgraded...
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posted on July 27th, 2003 at 06:11 PM
in.


well, it works.. after retarding the timing.(just a tiny bit) now i have to regap the plugs... shitty job with the engine in the car and twin Kads. if i blow it up i may need to switch back to the smaller gap.. anyone tried running std ignition with a big gap? hmm
i'm using the sprty coil, too, so i may have to change that back to a stock coil. for some reason it did seem to miss a bit after heavy driving, but that might be my blind attempt at retiming (twist n guess), or the coil.i'm gonna have to borrow mt ousley, i can feel it in my bones..:D




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posted on July 28th, 2003 at 10:33 PM


I think you'll find they're referring to the air-gapped type, not the old oil-filled GT40 and the same does not apply to a CDI, as far less power flows through the coil than in the standard Kettering configuration.

In a standard setup, the energy foor the spark is stored in the core (during the dwell period) and is released when the points are opened (if you measure the voltage across the points at this time, using a storage oscilloscope, you will find it hits about 200V.) Unfortunatley, a certain amount of current must flow in order to saturate the core through most of this period and this represents an energy loss in the form of heat. In the CDI, the energy is stored in a capacitor at, usually, around 400V, then applied to the coil using a high-speed thyristor or transistor. Thus, the energy produced in the spark is much higher, but the total energy fed to the coil is much lower.
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posted on July 28th, 2003 at 10:37 PM


i'm running an SU 120 bosch coil....
air gap? plug gap? wah?
now i'm confused. mebbe i'll leave the coil for now and just fiddle with the timing. *crazed look*




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posted on July 29th, 2003 at 11:53 AM


well after being so happy with my old box of ignition magic it just shit itself. Got home from work, stopped bus, got changed, went to start and no fire.

This is the good bit, I raced down the back and hit the switch to go back to conventional points and started str8 away. So my box of tricks has died. Post mortem results soon.

Dont think it was the GT40 coil as Ive used this box with one for years before. Must have been its service life up. Its chinese manufacture of early '80s vintage.

Now to replace it with one of the more modern ones. Im not keen on the magna dizzy as Ive been told the advance is all wrong.

Whatever I replace it with (eventually) I will definately install it with the switching set up so I can switch back to points if the SOB dies.

Hope this adds to the confusion........

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