slashdawg00110

cool. i'll look for it after your extended road test.

Jeff20B

iTrader: (13)

That's great that you got it working.

honegod

would you tell more abiut these coils ?

what does DIS stand for ?

bill Shurvinton

dis-less ignition. Twin post wasted spark jobby as fitted to heaps of cars these days.

Much smaller (and lower power) than the RX7 wasted spark coils. However don't see why they shouldn't work in a NA app.

Note before anyone jumps in. The mazda system IS wasted spark on leading, coil per plug trailing. I have seen some confusion on this issue.

honegod

ah yes, I have seen those.

thanks

Jeff20B

iTrader: (13)

You're a little confused. It's not supposed to be called wasted spark on a rotary, even though it uses a DIS coil for wasted spark from a piston engine. It's supposed to be called simultaneous firing. Do I need to sick RETed on you?

Since you seem to think that it is supposed to be called wasted spark, I'll tell you that RETed corrected me a while back when I was doing pretty much the same thing. There was a significant reason why it shouldn't be called wasted spark on a rotary, but I don't really remember it now.

By the way, what do you think I should call it on my 20B? Each leading plug will get 0º and 180º sparks, just like a two rotor engine, but each spark event will be timed every 120º due to the geometry of the E shaft. Yep, each leading plug will still get its 0º and 180º sparks.

As you can probably guess, wasted spark simply won't work here. It's the same idea as simultaneous firing on a two rotor, and will fire each leading plug just as often so each rotor face experiences the same amount of sparks; the only difference here is when rotors 2 and 3 get there sparks due to their geometry.

As far as I know, no other 20B has leading ignition quite like this.

I think the problem we have here with calling it 'wasted spark' came from websites like Craig's Rotary Page and others many years ago. Since his page is currently down due to too much traffic, I've copied and pasted the text from this cache from google. http://216.239.57.104/search?q=cache...hl=en&ie=UTF-8

Semi) Distributorless ignition

Not a new idea - Mazda have used this technique since the 2nd generation RX7 (1986-1991).
The basic idea is that on a two rotor engine, the leading plugs may be fired simultaneously, with one spark igniting the fresh air-fuel mixture in one of the rotors, while the other rotor will have a "waste" spark that will fire into the already burnt/still burning exhaust gas.

This is due to the geometry of the rotors being 60 degrees out of phase (when measured from the apex seals) - See example above.

One major provision is that the timing is not advanced nor retarded too much, as this may cause the 'waste' spark to undesirably fire into some fresh mixture. For this reason, this technique will not work on the trailing plugs.

Essentially a "dual ended" ignition coil is used, simply connected to the existing leading ignition system.
For example, a General Motors 3.8 V6 coil used with it's distributorless ignition. The whole system can be put together in under an hour if you have all the correct connectors and ignition leads available.

The advantages of this system are mainly that much higher voltages including CDI (Capacitor Discharge Ignition) can be used as there is no distributor cap to route the high voltage through, without fear of cross firing to the trailing spark plugs.
'Surface discharge' type spark plugs may be used - which replace the conventional ground electrode with a ring of metal around the centre conductor. I believe this allows more spark discharge paths, giving better ignition of the air-fuel mixtures.
In terms of power gain over a conventional early Mazda ignition system that uses a distributor, about 5% extra power may be gained.

Jeff20B

iTrader: (13)

Hey, it looks like Craig's Rotary Page is back online. Here is the link. http://cp_www.tripod.com/rotary/pg27.htm#ign

rotarydankus again

im fighting it again errati c tach and missing again,sittingonthe ******* it suddenly came to me i had mounted my modules up at the strut tower , I twisted mypickup wires ,then like an idiot i zip stripped it to the exsistingloomfeeding the disty and the alt andmyelect fan, whatta dumb *** huh?got some abs speedsensor looms from98 blazer wiring harness these babys got more shielding than nuclear defense circuits , hopefully this will cure it, trev

Jeff20B

iTrader: (13)

Hopefully. I once hooked my tach to one of my leading coils and noticed a jumpy tach. My leading pickup wires weren't shielded. The ignitors are over on the inner fender.

inittab

I wonder if running the GM HEI ignitor on the trailing will effect or alter the accuracy of the tachometer in any way.

rotarydankus again

wwwwwell the abs wiring with the sheilding seemsto have worked,also rerouted the wires away from any others, we will see, trev

Critoris

Dankus, check your PM's.