Fw: Types of Ignitions

[Tom Sharpe]

On Wed, 13 Feb 2002 12:13:07 -0800, Garfield Willis <garwillis at msn.com> 
wrote :

> 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
> 
Right on, The extra sparks are so late that they do little except keep the 
plugs clean. Retard your spark 10 deg. and see what happens to your power. 
I'd like to see someone build a CD that would "ring" the coil (set up a 
high frequency AC current) for about .005 sec. (5 deg. @ 6000 rpm). 
Probably take a lot of power, expensive components, and eat up those 
platinum plugs in 10K miles, but, hey, nothing's free.  Tom
PS I want guarantees that the fire is lit.




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