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Re: Ignition and sparks

To: Paul Hunt <>
Subject: Re: Ignition and sparks
From: Charles & Peggy Robinson <>
Date: Sun, 05 Feb 2006 21:32:40 -0600
  Ida no, Paul,

   With the big bore two valve engines thare was a need to speed up the 
flame front so as to complete  the burn before the exhaust valve opened.
With the advent of of higher revving multi valve engines the same 
applies: ake sure that the intake charge is completely burned before the 
exhaust cycle begins.  If you ignite the charge from both sides, you 
shorten the time for complete combustion.

   Tha same can be said for hotter or extended spark ignitions.  I 
believe the question of how much any of the ignition tricks depends on 
the individual application.  But I wouldn't dismiss any of them on an 
engine in good tune.



Paul Hunt wrote:
> Like many other 'go-faster' bits they add little if anything to a generally
> factory spec car in good condition other than cost and the opportunity for a
> bit of bar-room bragging.  Where they *can* make a difference is in marginal
> conditions like cold and damp, poor state of tune, weak battery etc.  There
> have been such devices around since the 70s and earlier, and one passive
> device I was aware of reckoned to deliver multiple high-frequency sparks
> from a standard HT system by the use of multiple air gaps.  The principle
> worked - on a couple of occasions I got my Mini going by wiggling the HT
> lead a little way out of the coil while someone else cranked it, which
> always got it going whereas previous cranking hadn't.
> In theory twin-spark systems can complete the burn in half the time and so
> give a bit bigger bang initially, but since I have only seen them in Alfa
> Romeos I rather suspect it was a case of 'if the first spark doesn't set it
> off the 2nd will'.  If it made any difference at all then all performance
> cars would have had them for years.
> PaulH.
> ----- Original Message ----- 
>>I once read a piece which said that high voltage coils (big
>>sparks, multiple sparks etc) were unnecessary and just fodder for the
>>I-wanna-go-faster-so-give-me-racing-stripes fraternity.

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