Don,
according to my info, a plug that has a shorter ceramic path to the
shell is the cooler one, (ie) heat is conducted away qiucker due to the
shorter path to the air or water cooled head.
Chris Harris New Zealand.
----- Original Message -----
From: "Don Kerr" <dkveuro@pop.flash.net>
To: "Jim Dincau" <jdincau@qnet.com>
Cc: <land-speed@autox.team.net>
Sent: Sunday, July 30, 2000 11:36 AM
Subject: Re: Spark Plugs
> Jim. if the originals are doing a good job, then the next cooler for
> high speed will be safe for sustained high loads. That is, a plug with a
> longer ceramic path to the shell. However the only way is a dyno pull,
> to compare HP output, as I have had an engine give up 38 hp at 7000rpm
> with the wrong plugs. The mag will deliver a hotter spark if the
> potential is built into the plug circuit and changes very little in the
> final combustion temperature from the original ignition, unless, you are
> using a hotter plug to prevent cold/oil fouling or to promote fire from
> a bad combustion chamber design in the first place. Ignition initiation
> is a process of the ironitation of a very small kernel of air around the
> plug electrode, the change in ignition spark is not so much a better
> spark but being able to cause a better spark by increasing the
> resistance to ironitation at the plug by wider gap, higher compression
> or a change in fuel/air ratio coupled with the swirl action of the
> intake fuel mixture, or all or part of the above.
> If a plug needs 12500 kv to fire it ,it will need 12500 kv
> to fire with any ignition system type. The kernel starts the action by
> ionizing the air much like a lightning strike does to the atmosphere,
> just milliseconds before the main bolt strikes the faint upward leader
> from an initiation point. The advantage of mags is that their spark gets
> hotter up to a point as rpm's rise. Some while ago a CD ignition was the
> way to go, now there are many different types to choose from, but mags
> don't need the added wiring a conventional ignition does.
> Power in an engine is a way it uses the air it breathes and
> the combustion temperature should see no great change as it is a
> chemical reaction regardless of the power it produces, just the amount
> of calorific BTU's it now has to dump, which leads to a larger/better
> radiator. etc etc etc etc.......
> DK.
> PS.....O'corse there will be some who don't agree, and will take issue
> with what I've said here, but that's OK, I'm not the final authority on
> ignitions.........YET! :-)
>
>
>
>
>
>
>
> Jim Dincau wrote:
> >
> > Magneto Don.
> >
> > ----- Original Message -----
> > From: Don Kerr <dkveuro@pop.flash.net>
> > To: Jim Dincau <jdincau@qnet.com>
> > Sent: Friday, July 28, 2000 5:44 PM
> > Subject: Re: Spark Plugs
> >
> > > Depends on the ignition system Jim.........DK.
> > >
> > > Jim Dincau wrote:
> > > >
> > > > Hi all:
> > > > Here is a question for the group;
> > > > Is there a difference in heat range required of the spark plugs in a
> > > > normally aspirated alcohol engine versus a gasoline engine? This is
> > > > assuming both are tuned up to the max re; cam compression and
> > breathing.
> > > > Jim in Palmdale who has nothing better to do.
> > >
>
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