Electronic ignition for VW

Dave Unwin · Post by **Dave Unwin** » Mon Oct 03, 2011 10:57 am

Hi All, I'd really like to put electronic ignition in my VP-1. Does anyone have any experience of the Trigger Wheels system, or a current contact for Leburg?
Cheers, Dave

Nick Allen · Post by **Nick Allen** » Mon Oct 03, 2011 11:29 am

Have you tried contacting Henry Mickleburgh?
http://www.leburg.com/index.php?p=1_3_Contact
I got a response from him to a query last year, though someone here said he had been elusive of late.

Dave Unwin · Post by **Dave Unwin** » Mon Oct 03, 2011 11:36 am

Yup - emailed and left a message on the phone. That was about a week ago, currently, no joy.

Rob Swain · Post by **Rob Swain** » Mon Oct 03, 2011 2:29 pm

I'm assuming you've read the article on home-brewed ignition in the August LA mag.
I'd be tempted to look into that system.

I've fitted and flown the Leburg system. It is very good, but can't be regarded as cheap. I don't blame Dave Mickleburgh for that: it's the nature of small production run engineering!
When DM was still with us the system could be regarded as good value as his support was very good, but that's a bit of an unknown quantity now, by all accounts.

As a matter of interest the normal Leburg system is based on the same Ford ignition coils as in the Megajolt although DM also recommended and used 4 Honda bike coils. The bike coils are smaller and lighter, but potentially cost a lot more.

Dave Unwin · Post by **Dave Unwin** » Mon Oct 03, 2011 8:59 pm

Hi Rob, I have - very interesting it was too.

JohnLindsay · Post by **JohnLindsay** » Wed Oct 05, 2011 1:01 pm

Hi Dave, I have PM'd you with a possible contact.

Nick Allen · Post by **Nick Allen** » Wed Oct 05, 2011 2:20 pm

I was browsing t'internet last night and found someone selling a Megajolt setup for aircooled VWs:
http://www.trigger-wheels.com/store/con ... k/d45.html

Dave Unwin · Post by **Dave Unwin** » Wed Oct 05, 2011 2:24 pm

Thanks John. I've been in touch with Trigger Wheels Nick - has anyone out there got a Trigger Wheels Megajolt on a Veep?

ColinC · Post by **ColinC** » Wed Oct 05, 2011 3:44 pm

Hi, reading this got me thinking and I re-read the Megajolt article last night. That discussed a single megajolt and a magneto.

Am wondering how it would work out with two independant Megajolt systems which seems a good alternative to the Leburg. The reluctor is set up with the missing tooth at 90 degrees btdc. How would that work with two sensors?

regards,

Colin

Nick Allen · Post by **Nick Allen** » Wed Oct 05, 2011 3:58 pm

I'd been going through the same thought process, Colin!
Can one just have two sensors siamesed together, pointing at the same gap?

Dave Unwin · Post by **Dave Unwin** » Wed Oct 05, 2011 9:01 pm

Interestingly, two brand-new Trigger Wheels systems is coming in cheaper than having my two old mags overhauled, so I'd certainly like to go that route!

ColinC · Post by **ColinC** » Wed Oct 05, 2011 10:04 pm

Nick Allen wrote:I'd been going through the same thought process, Colin!
Can one just have two sensors siamesed together, pointing at the same gap?

Have had a long day and my mental capacity may therefore be diminished, but I'm thinking that the solution involves mounting two sensors, one 90 degrees before tdc as standard and one 90 degrees after.

Then, by re-arranging the plug cables on the 2nd system the correct firing coil to cylinder relationship can be restored.

i.e for firing order 1324 on the engine, system 1 would be wired conventionally but on system 2 the coil labelled for cylinder 1 would actually fire 180 degrees late so would go to cylinder 3, coil 3 to cylinder 2 etc instead.

I think that the ford system would be expecting to fire in the order 1,3,4,2 so a rearrangement of the coil to cylinder order would be needed on system 1 too for most aircraft engines.

Does that make sense? It is a wasted spark system, so you get a spark on every revolution on each cylinder.

Steve Brown who wrote that article is presumably the same Steve who posts on here so hopefully he will update us on progress at some stage.

The problem of complete redundancy needs addressing, Steve's proposal was for a mixed mag/electronic system. The Leburg system used a generator, battery and backup battery so presumably this could be emulated in a Megajolt based system.

A major driver for my interest is to achieve a weght reduction over mags and the opportunity to move some weight as far back as possible. Even if the weight reduction is not considerable, replacing the mass of mags on the engine with controllers behind the firewall and batteries well behind the C of G would be attractive. My engine has a small crank driven alternator fitted already so that is helpful.

regards,

Colin

PS: I noticed that there is an ad for trigger rings in the October LAA mag so someone's working along the same lines

Steve Brown · Post by **Steve Brown** » Thu Oct 06, 2011 10:40 am

Yes - Colin has 'got it' spot on.

The plug leads are redirected to the appropriate spark plugs to mirror the 'paired' pistons.
On the Ford in line four EDIS engine, the 2 outer pistons (No 1 & No 4) rise & fall together for good balance, as do the inner 2 pistons (No 2 & No 3) . So the paired (ie 'active+wasted' spark together) coils similarly are paired ie 1&4 and 2&3.

On an O-200 for instance, the opposing cylinders (where the pistons go in and out together for good balance) are No 1 & No 2 and No 3 & No 4. Thus simply re-direct the plug leads such that the paired coils are paired as 1&2 and 3&4. (In my case, on the coil itself, I simply re-numbered connection 2 as 4 and 4 as 2!).

Just apply the same principle to any engine inc the VW.

Also the sensors would indeed most simply be placed 180 deg apart on a dual Megajolt system.

Nick, note that if it is possible to physically mount both sensors at one point 90 deg BTDC, this could also work 'ignition timing-wise' - providing the magnetic flux of the two sensors are not able to influence each other and they can still be triggered effectively by the missing tooth.

The car based engines such as VW will likely be much better served ref availability of off-the-shelf trigger wheels than the a/c engines. Finding a reliable place for such a trigger wheel on an aircraft engine is a little more difficult but I am sure others can surpass my ingenuity!

Precisely the purpose of the article!!

Regards
Steve

Nick Allen · Post by **Nick Allen** » Thu Oct 06, 2011 12:59 pm

All very interesting and helpful stuff! Thanks chaps. Looks like it should be quite feasible to construct an alternative to the Leburg from off-the-shelf components...

ColinC · Post by **ColinC** » Thu Oct 06, 2011 1:09 pm

Thanks Steve,

I'm assuming that it would be ok to use a flat plate wheel trapped between the prop and the driving flange? Am not sure where that leaves you with something like a Continental with the threaded inserts on the flange as it reduces the depth of bush in the prop.

If anyone is wanting to experiment with this system and wants a trigger plate making up I can probably get them drawn up and laser cut to suit any specific configuration and bracket orientation that may be required.

regards,

Colin