Electronic ignition for VW

Dave Unwin · Post by **Dave Unwin** » Thu Oct 06, 2011 2:10 pm

Hi Colin, I may well take you up on that. I'm not having much joy at all with sorting these mags out, and would much prefer dual electronic ignition anyway.

ColinC · Post by **ColinC** » Thu Oct 06, 2011 5:42 pm

Hi Dave,

I used the experiment word because we are a long way off having a system in place that you would get approval to test fly.

The process of getting the engineering and reliability sorted to a state where it can be put to the LAA will take many man hours and will not happen overnight. If you want to fly then sorting the mags may be the expedient solution for now.

regards

Colin

Dave Unwin · Post by **Dave Unwin** » Thu Oct 06, 2011 7:54 pm

Hi Colin, I was afraid you were going to say that!

ColinC · Post by **ColinC** » Thu Oct 06, 2011 11:22 pm

hi,

I wasn't wanting to put anyone off, quite the contrary in fact, as if the Leburg system is gone forever a viable replacement really should be found. Sorry if my comment was read in that way.

I'm sure that Engineering will do what they can to help, but their job is oversight and not development. A member needs to pick up the challenge and run with it. Steve Brown has demonstrated what can be done, but perhaps someone with a vw powered single seater could do some development on a dual system that includes a generator and so becomes a viable Leburg replacement.

David Mickleburgh's ideas for the alternator are an LAA accepted solution and are in the public domain. The controllers and coil packs are off-the-shelf.

If you are keen enough why not go for it, I'm sure that you will find that there is a wealth of knowledge and help available via the LAA's network of members and Inspectors. Steve Brown said in his article that he's happy to help so that's a great start.

regards,

Colin

Rob Swain · Post by **Rob Swain** » Fri Oct 07, 2011 10:00 am

ColinC wrote:I'm assuming that it would be ok to use a flat plate wheel trapped between the prop and the driving flange?

Can't remember for certain, but I have a feeling this has been done for fitting a Leburg system to a small Continental. I think DM's introductory blurb had pictures of such an installation.
On a Leburg system the plate held the trigger magnets.

As regards the 2 triggers from one wheel problem listed above (already solved for the VW, I know!) another alternative would be to put the pickups about 10 degrees apart and program the offset into the ignition I believe the article said this was possible, presumably to allow for slightly dodgy engineering in cars.
One could be set 5 degrees ahead and the other 5 behind, but I think I'd try to set it so one was spot on and the other 10 degrees later. That should avoid the risk of an overly advanced spark in the get-you-home mode (if my geometry is correct!).

rogcal · Post by **rogcal** » Fri Oct 07, 2011 10:22 am

Some of you may recall my earlier thread some months ago on finding an alternative to the Leburg system and although since then I have reconsidered my options and have decided to stick with Lucas SR4s for the foreseeable future, my foray into the world of alternative systems came up with very little in the way of "simple" and I stress the word simple, off the shelf components with which to develop it.

The main reason I'm posting this is to give a hint that something may be happening on the Leburg front but it may well be months rather than weeks before anything can be confirmed and I would have preferred to say nowt just in case it all goes belly up.

However, as a few of you seem to be about to embark on seeking an alternative system when the Leburg system may not yet be fully dead and buried, it would be remiss of me not to say something.

Some of you may already have an inkling as to what may be going on behind the scenes and understand the delicate nature of the negotiations being carried out but I would ask that those who are not in the know, please hang in there for a little longer however, don't press me for details at this stage as I shan't be disclosing anything.

For those of you determined to go down your own route or utilise Steve Brown's system, go for it and if someone does come up with something simple using off the shelf components that would be great, even if the Leburg system does get resurrected, as it will give people choices and that's not a bad thing.

ColinC · Post by **ColinC** » Fri Oct 07, 2011 10:43 am

Roger,

thanks for your comment, I am sure that people will repect your position on that and leave you to add more detail as appropriate.

Your statement at least offers hope for those who need a supported solution.

Colin

ColinC · Post by **ColinC** » Fri Oct 07, 2011 6:04 pm

Here's a basic description of the Ford EDIS system:

http://www.dainst.com/info/edis/edis.html

Reading this has left me wondering about a simpler if cruder solution, but I may get soundly abused for even suggesting it.

However here goes.....

The key point is that the Ford EDIS can work standalone.

An EDIS with no signal goes into it's fall back mode and triggers a spark at 10 deg btdc. So, an EDIS with no signal and a sensor/missing tooth at 110 degrees btdc fires at 30 deg btdc.

Switching it over to an alternate sensor at 75 deg btdc fires the plug at 5 degrees after tdc (or wherever you choose according to the geometry) which means no kick back on starting.

A second sensor at 160 degrees after tdc can drive the second system firing the second cylinder at 30 deg btdc.

So, you now have a startup mode on system 1 only. You switch on system 2 after starting with its fixed advance at 30 deg btdc which now supplies the leading spark. Then switch system 1 to its alternate sensor so it is now also operating at 30 deg btdc. That sequence could be simplified by wiring through an appropriate rotary mag switch.

The question is, could that be built to be at least as efficient/reliable as a couple of bendix mags on the back of a VW with their fixed timing and no impulse? There would seem to be potential weight savings and hopefully improved safety/ease of starting at least.

Colin

Steve Brown · Post by **Steve Brown** » Sun Oct 09, 2011 2:07 pm

No abuse from me! - it is perfectly feasible to do as you suggest by not having any SAW signal back to the EDIS module ie not use a Megajolt at all and instead rely on adjusted 'limp home' fixed timing - with an additional retard sensor switched over for starting. Nice idea.

No real issues there except that using a trigger wheel to compute speed and then not use it is 'over-spec' and the efficiency benefit of advancing ignition at part throttle / altitude is lost.

There may be simpler/lighter car or motor cycle based fixed ignition systems using a hall effect sensor and embedded rotating magnet that could be used instead.

Regards
Steve

ColinC · Post by **ColinC** » Mon Oct 10, 2011 1:39 pm

I was looking at another uk made system (can't remember which now though!) that allowed you to set where the crank sensor was. That would mean that you could position it for whatever advance you want in 'limp-home' mode.

That would be better than just taking the Ford 10 deg btdc setting.

EDIT: the system was Canems and they were very helpful in answering enquiries: www.canems.co.uk

ColinC · Post by **ColinC** » Thu Oct 13, 2011 5:13 pm

Something that I have learned which is very relevant to the idea of electronic ignition is that most after-market ECUs need the engine to be spinning at constant speed for a couple of revs in order to determine the crank position and speed before they fire.

That makes hand-starting a problem!!