DIS Explainations

[Shannen Durphey]

Pete Datcuk wrote:

>   Think of the two spark plugs as two resistors in series.  Their resistance adds, but the wattage of each will be different, the plug with the higher resistance consuming more wattage (ie watts = current x resistance squared).  If one of the plugs doesn't arc, then the circuit is not completed, and the other plug will also not fire.
>

Gotta tell ya.  If one plug doesn't fire, quite often the other one will.  In fact, if it runs this way long enough, there will be a burn through of the coil's epoxy insulation.  I'm not going to attempt to explain why it will spark, but it does.

Shannen

> Pete Datcuk
> Mechanical Engineer
> Sewell, NJ
> '87 Fiero, soon to be Northstar'ed :-)
> '67 Jeep Commando, to be risen from the dead ;-)
>
> -----Original Message-----
> From:   Michael Baxter
> Sent:   Sunday, March 22, 1998 2:47 AM
> To:     Blind.Copy.Receiver at compuserve.com
> Subject:        Re: DIS Explainations
>
> John Hess <johnhess at cris.com> writes:
>
> >> Actually, you can have a spark in a vacuum!
> <<
>
> Air is an insulator. The more air molecules (denser), the better insulator
> it makes. A good example, just because they've been discussed on the list
> before, is WWII airplanes. Their magnetos were pressurized to keep the
> ignition energy under control at high altitudes. Without the
> pressurization, the engines would start to misfire at 18,000-20,000 ft.
>
> High altitude piston engine airplanes today still have pressurized
> magnetos.
>
> I can offer no clues as to why the waste spark only consumes 20-30% of
> the spark energy in a DIS ignition system that fires two plugs at once.
>
>  -- Michael Baxter, MBaxter at Compuserve.com
>  http://ourworld.compuserve.com/homepages/MBaxter
>  From Reno, NV USA on 21-Mar-1998
>
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