Fw: Types of Ignitions

Garfield Willis garwillis at msn.com
Thu Feb 14 08:03:47 GMT 2002


On Wed, 12 Feb 1997 17:04:02 -0500, "Bruce" <nacelp at bright.net> wrote:

> Now, with the CDI, and a 400
> volt primary, when you figure that with a 100:1 coil, you can see that it
> instantly (well almost) can make 40,000 volts on the secondary side to
> strike a spark.   SO THAT HAS TO BE GOOD, RIGHT, well not really. In this
> being able to do it instantly means that the spark only lasts for an
> instant, the most often used strategy to over come this, is using several
> sparks or rather coil firings to get the reaction going in a proper manner.
> In a high turbulence chamber, this might even be a good thing, but, your
> still dialing with HAVING to have seveal sparks.

This is especially evident when you're dealing with alternate fuels, such as
methanol.

The problem with multiple sparks is that at high rpm, you don't have much
TIME for more than one or two jolts, so even there, multi-spark has it's
limitations. Fortunately, increased turbulence with rpm helps out a good
deal.

CDI seems to continue to work well enough on the highest performance
gasoline turbo Saabs. Interestingly, on the Saabs, the ONLY time they
multi-fire the CDI is to clean the plugs at shutdown! Seriously, they
dry-fire the plugs hundreds of times in rapid succession then, for a good
scrubbing, in preparation for the next startup. Clever them Svenski's, eh?

Gar

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