DIS Explainations

Raymond C Drouillard cosmic.ray at juno.com
Sun Mar 22 19:33:15 GMT 1998


On Sun, 22 Mar 1998 02:53:49 -0700 Clint Corbin <ccorbin at Rt66.com>
writes:
>At 10:17 AM 3/22/98 +0100, you wrote:
>>On Sun, 22 Mar 1998, you wrote:
>>
>>> 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.
>>
>>The clue is that one cylinder is at atmospheric pressure (or
thereabouts)
>>whereas the other plug is at compression pressure. Air is an insulator,
>>the effect of which increases with pressure as you note. This means
that
>>the resistance at the plug exposed to low pressure is much less than
the
>>resistance at plug exposed to high pressure. Basic Ohms law tells us
that
>>the voltage drop over the high pressure plug will be much higher. 
Since
>>the current is the same, the energy at the high pressure will be
higher.
>>
>>Egil
>
>Don't forget, the gas in the cylinder that's get the wasted spark is
also
>very, very hot.  Good chance that a lot of this gas is already ionized,
>further reducing that plugs resistance.
>

Are the plugs wired in series?  How is this accomplished?  Since the
outer electrodes of all the plugs are grounded to the block, I was
assuming that they were wired in parellel.

To wire them in series, we would not be able to use the standard
autotransformer.  Instead, the secondary would have to float.  Also, the
direction of the current would have to be reversed based on which plug is
to be fired, since the plugs are designed to work with a specific
polarity.

Ray Drouillard

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