CDI Alternative? Link/MW ignitions?
 

A thread came up on the Rennlist 911 board about a new CDI replacement, from a company from Australia, "Link Electrosystems" that makes engine management systems offering a replacement CDI box. Link's web page can be found here, but makes no mention of any ignition products.

A couple people were raving about it, and posted a contact number. Well, I called and spoke with one a guy at Link. and this is what the he told me:

He said that Link has been in the engine management business for a long time, and the CDI is an adaptation of an off-the shelf CDI they already sold. He said that they provide CDI units to Motec.

Apparently if you buy from them, they fabricate a short harness that plugs into the stock CDI connector into their CDI box. The box has what he called a "standard flat Bosch connector"

More interesting is the twin plug adaptation. Their twin plug CDI is just a standard unit with higher output, and uses the stock harness. All you need to do is add a second coil and connect the standard 2 wires to both, either by splicing in a splitter, or by making a simple pair of jumper wires between the terminals on the coils.

There was some other nice stuff, like an LED on the box to tell you if it is working, short protection, so if your coil shorts it won't fry the box. He also said it was all digital, and that Permatune and Bosch are Analog.

I asked for some documentation, and they sent me a photocopy of a catalog page, which I later found out was a page from yet another company's catalog (the contact info at the bottom was chopped off in what they sent me). Here is the catalog page, with the specs of the unit:
http://members.rennlist.com/emcon5/CDI.jpg

Anyone ever used a MW ignition box?

I doubt any claims of performance gains, unless the stock unit is lacking in some way. I am more interested as possibly cost effective replacement for a Bosch CDI or more reliable alternative to Permatune.

I like the concept of how they do the twin plug thing, but I am really sceptical of the wiring to the coils. The splitter thing doesn't sound right to me. I would think the coil with the least resistance in the wire would get the most juice.

If someone who knows a lot more about ignition systems could comment on this, I would appreciate the input.

Thanks,

Tom

Re: CDI Alternative? Link/MW ignitions?
 

A thread came up on the Rennlist 911 board about a new CDI replacement, from a company from Australia, "Link Electrosystems" that makes engine management systems offering a replacement CDI box. Link's web page can be found here, but makes no mention of any ignition products.

Hey! Credit where it is due! The Aussies might have invented MoTeC, Autronic and Haltech (all better than Link) but New Zealand is where Link comes from!!!! NZ site is here:

http://www.link-electro.co.nz/home.html

As an aside, I reckon their Ignition Link (ignition mapping only) would be an awesome addition to a CIS car.

The MW stuff is from Aussie though.

More interesting is the twin plug adaptation. Their twin plug CDI is just a standard unit with higher output, and uses the stock harness. All you need to do is add a second coil and connect the standard 2 wires to both, either by splicing in a splitter, or by making a simple pair of jumper wires between the terminals on the coils.

I don't know enough to comment on whether this is ok. For clarity (for other people) I saw on the Rennlist thread you are using a 964 twin plug dizzy. Two coils means twin plug dizzy (or RSR dizzy).

I'm gonna follow this up for my own car (twin plug, MoTec, no CDI, plug fouler with S cams). I figure I can either insert 1 or 2 of the MW CDIs between the coil and ignitor.

Cam

Tom, that does look interesting, but the problem w/ going to dual plugs has always been the distributor. You can do the modified 964/993, or the very expensive oem, or Electromotives kit or this one which also looks interesting.

MSD digital distributorless ignition

Like the Electromotive it would solve a lot of problems at once.

Link resells, or sells as a part of there engine management systems, M&W ignition systems. I bought LinkPlus engine management and it came with M&W ignition modules, these are not cdi units. The M&W website has a porsche specific CDI for 3 pin, 6 pin. Link seel both the inductive and capacitive M&W igniton boxes. I havent got my engine up and running, but from what I can tell the Link and M&W components are first rate.

This is my coil pack and harness with M&W ignition modules, that will fit between the carbs.


http://forums.pelicanparts.com/uploads/ignition1_1.jpg

Tim, Does that eliminate the distributor? Sure looks like it. Where does the TDC or whatever reference signal originate?

Cam: I stand corrected. I by no means intended to slight your lovely islands, and humbly beg forgiveness ;)

Good point with the clarification, a good old-fashioned distributor is still required, as is 2 coils. My plan is to have Rennsport do a 964 conversion on an extra SC dist. I still need to find a used 964 distributor.

I am in California, so I will be stuck swapping the ignition every 2 years for smog checks, so ease of instalation is pretty important to me. I was thinking of 2 MSD's, or the smaller Crane units, with the associated wiring nightmare. Using the existing wiring harness is a huge bonus as well as not needing to find a place for two large MSD boxes.

Bill: The MSD digital solution looks promising. If I changed directions and went with a crank fired unit, it would be Clewett's Electromotive kit. There is a lot to be said for getting everything in one engineered package, even if it isn't the least expensive way to go. Saves in frustration later.

On the other hand, I have always prefered to do things as low-tech as possible. A 964 based mechanical advance distributor is pretty low tech, with the added bonus of readily available/inexpensive (relatively, compared with RSR parts!!!!) caps and rotors.

Tim: The image in my first post is from MW's catalog, which I downloaded from their website. Unfortunately it doesn't list a twin plug application yet.

I think I will send MW an email asking about adverse effects of differing resistances in the wiring and it's effect on output of the coils.

Tom

I have a clewett trigger ( motronic 60 tooth, 2 dropped tooth wheel) and the LinkPlus. Ill be running it ignition only until I get TWM throtttle bodies and then use the EFI capabilties of the Link ( on a 2.2 :p ).

M&W does make a replacement CD cox for the Bosch 3 or 6 pin ala permatune. Obviously it isnt marketed that well here.

I am still assembling the system, and havent fired it up yet so there is still a large learning curvce ahead.

The electrmotive is popular.. but ive seen some odd drop outs on the dyno graphs with the hpv1 and hpx.

Tom,Tim great and interesting stuff here. i've been trying to learn so much about Motronic and Motec that I've gotten out of touch w/ this stuff. Keep us posted!

Tim, is that the regular 3.2 911 Motronic fly wheel? Sounds like it.

Bill, the clewett trigger, replaces the fan pulley, the pickup mounts where the dist used to live.. it uses the dropped tooth as a reference to TDC, then the "brain" counts teeth to signal firing events.. I just caught onto Tom trying to split the CDI signal to fire 2 coils. Maybe I diluted this thread a bit, but M&W appears to make a very high quality product.

I sent an email to MW yesterday, I was expecting to get a reply today. Then I remembered that pesky international date line thing, and it is Saturday there. When (If?) they reply next week, I will post what they say.

I am still hoping a CDI expert will chime in on the feasability of the 2-coils-one-CDI-twin-plug thing.

Tom

OK, got an email back from MW. I asked:

Now, my understanding of electronics is pretty basic, but wouldn't the impedence of those coils not be identical, so one of the two would see more current?

He replied: I then replied asking which coils they reccommend, to which he answered:

Opinions?

Tom

I remain skeptical about the mis-matched impedence of the coils.

His argument is that the coils tolerence is so tight it doesn't matter.

Two thoughts -

1) if that were true, then I imagine any CDI could drive two coils with a Y splitter

2) why would coil manufacturers hold such tight tolerences on the primary impedence? They aren't designed to solve a Y connection problem and it would cost a lot to hold the tolerence.


I suspect that he is correct, in practice it does work. But the spark energy delivered to the two plugs will not be equal. Maybe it's "close enough" and a non-issue. I'd like to hear from people who have actually done this.

I would really like to get some solid tech on this. All I have got so far is from the vendor or anecdotal.

A couple guys have said "Yeah I use it, works great" but nobody has any solid evidence or even theory as to how well one CDI can drive 2 coils.

Can anyone else provide some input on this?

Any electrical engineers in the house?

Tom

Tom, Have you looked into either of these 2 setups from Andial Twin Plug Setups

http://www.andial.com/content/images/dualplugb.jpg

http://www.andial.com/content/images/dualpluga.jpg

Briefly.

The version for my car is a conversion of my distrinbutor to use a Bosch 12 pt Cap and rotor. This is clearly the most elegant solution, but unless someone starts production of the caps and rotors, this is not realistic. The last C&R set I saw for sale was over $1,500. I must admit, it sure is pretty:

http://forums.pelicanparts.com/uploads/pp3.jpg

The Rennsport conversion uses readily available 964 tune up parts. Besides, when was the last time anyone from Andial was on this forum or Rennlist dispensing free tech info? ;)

I am interested in Andial's conversion harness though. One of the reasons I am interested in the M-W setup is the use of the factory harness. If Andial's harness is essentially plug and play, I would much rather go with proven technology (Bosch) than something brand new.

If I get time tomorrow, I will call Andial and see what I can find out about their harness, and just for grins, their current price on the 12pt cap/rotor.

Who knows, maybe the Permatune guy will chime in on this.

Bill, you know anyone with a spare 964 distributor that might be for sale? For that matter, a good used 6 pin Bosch CDI?

Tom