Okay, I see a lot of direct fire setups and each one sends a direct signal to the leading coils. The trailing coils are left to fire off the distributer. Why?

If my understanding of direct fire is accurate then the leading coils are sparking continuously, and with signifficantly more energy in each spark. This leads to a more efficient combustion, which means more power/economy/etc...etc...etc...

Why are the trailing coils left to fire with the distributer instead of wiring each plug to it's own independant spark source? Kinna like FC/D ignition.

 

the leading plugs are desined to fire at the same time every time, the trailing plugs just fire one at a time

 

hmmm...makes sense.

 

The trailing igniton isn't really critical for power, more so for economy and emissions, so upgrading the trailing isn't really necessary, aside from being a PITA for the reasons posted above.

 

i suppose you could use two coils for the trailing, but you would have to run both through the cap, one plug through the leading cap place, and the other through the trailing, but there is absolutly no gain in this.

 

why not firing all 4 of the plugs all the time?

 

it would run like a single rotor car then
the torque sould suck

 

the rotor phasing isn't right

 

If the leading fire at the same time, then shouldn't the trailing also fire at the same time? Not the same as the leading, but the same as each other. I can understand not needing individual coils, cause it'd be overkill, but I'd think that firing at the same time would make the engine run a little smoother, wouldn't it?

Just wondering,
Brian

 

I think that I MAY understand. The rotor encounters the plugs at wierd intervals. The trailing plug is exposed to the fuel/air mix first, and before it is compressed to the propper setting. If the trailing coil is firing constantly then preignition would occur.

 

Bingo. It's due to the timing and location of the plugs in the housing.

You can fire the leading together because when one rotor is at TDC the other is in the exhaust cycle. This extra spark actually helps reduce emissions slightly.

You can't do this with the trailing because the apex seal has already passed the spark plug and it would be firing into the incoming air/fuel mixture.

 

That makes sense. Thanks guys. I guess I just hadn't thought it through enough.

Brian