CDI powerful multi-spark

[BUTLER, Tom]

The energy delivered to the combustion chamber by even the most powerful
ignition system is insignificant compared to the energy produced by the A/F
charge burning.  Even if the spark were capable of pitting the piston,  the
sparking occurs while the piston is still relatively far from the top of its
stroke.  Remember that the spark gap is set to as wide a gap as possible and
still spark reliably.  The distance from the center electrode to the piston
is usually many times the gap width.

> -----Original Message-----
> From:	Falb, John [SMTP:John.Falb at Unisys.Com]
> Sent:	Thursday, December 10, 1998 12:46 PM
> To:	'diy_efi at efi332.eng.ohio-state.edu'
> Subject:	RE: CDI powerful multi-spark
> 
> Never heard of a spark being able to do any damage. Sure the timing of the
> spark can definitely cause problems, and a lean mixture will cause a
> piston
> to melt if pushed that far. I would believe that there wouldn't be so many
> people making CD ignitions if they caused peoples motors to melt. The
> spark
> only ignites the mixture, the mixture is what caused your problems, it was
> too hot.
> 
> John Falb 
> 
> -----Original Message-----
> From: Michael Farrugia [mailto:mikefarr at hotmail.com]
> Sent: Thursday, December 10, 1998 6:53 AM
> To: diy_efi at efi332.eng.ohio-state.edu
> Subject: Re: CDI powerfull multi-spark
> 
> 
> Unfortunately there are no O2 sensors fitted,  But before we engine blew 
> we put out the plugs and realised that the mixture was a bit week.  We 
> increased the size of the jets but it seems the harm has already been 
> done.  It was loosing a bit of performance when it got to 5000 on top 
> gear , on lower gears performance was better.
> I can understand that weak mixture can heat up the chamber but I have 
> heard it from two sources that very powerful spark can melt the piston.  
> Can this be true?
> thanks
> Michael
> 
> >> I have put a CDI which gives a fairly powerful multi-spark on a 2 
> litre 
> >>  Ford pinto engine.  This engine is tuned to go up to 8500 RPM.
> >>  However after some runs the engine broke.  When we opend the engine 
> up 
> >>  we found that on piston was melted.  A friend of mine told me that a 
> >>  powerfull spark may be the cause.  Has anyone encountered such a 
> >>  situation and how can it be rectified.
> >>  Thanks in advance
> >
> >That souinds more like (1.) lean mixture, or (2.) (less likely) 
> retarded
> >timing.
> >  Either can cause combustion chamber temps to soar...But, retarded 
> timing
> >will cause a serious reduction in performance, which wasn't mentioned,
> >so I'd wager the "lean-out" scenario is what took place...
> >Do you have any data such as O2 or (?) readings?
> >Mike V.
> >
> 
> 
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