[Land-speed] Odd car related stuff...

[Dave Dahlgren]

I think most passenger car systems are still inductive just replacing a 
transistor in place of the points. The system will not generate a voltage 
that is higher than the resistance at the plug gap. If you put an ignition 
scope on an engine and play with plug gaps and watch the voltage levels 
change. I am not so sure the billionth of a second spark is a good idea 
because if you miss the chance to get the mixture lit your chance for that 
cycle has passed. Conversely if you have a long burn time at the plug you 
stand a better chance to catch the mixture an lite it. This is how a magneto 
works.. and why they need a small plug gap to start up. I am sure there are 
a few cd units on cars but not convicted it is mainstream. With the advent 
of coil near plug and coil on plug the need for the fast rise times of cd 
systems is mitigated for the most part.
Dave
----- Original Message ----- 
From: "Bryan Savage" <b.a.savage at wildblue.net>
To: "LSR" <land-speed at autox.team.net>
Sent: Thursday, February 07, 2008 5:03 PM
Subject: Re: [Land-speed] Odd car related stuff...


>I looked at the web site. The plug may help on my '71 F-250
> but it won't have any effect on my '79 Ford Ranger.
> Why?
> The wiring diagram that they display, is of a breaker point ignition.
>
> Modern ignition system work much differently.
> They talk about their thing generating a pulse of electricity.
> Well, that's exactly what modern ignition systems do.
> A modern system does not use a "coil", it uses a pulse transformer
> just like the ones used in radar transmitters. The control unit
> sends a pulse of several hundred volts, about 10-100 microseconds long,
> to the pulse transformer hooked to the plug. About 1.5 microseconds
> after the pulse arrives the voltage at the plug goes from 0 to about
> 50,000 to 100,000 volts.
> Modern racing ignitions send a much higher voltage to the pulse
> transformer creating an arc at the plug in less than 1 microsecond
> that has an enormous amount of power (watts). The spark at the plug
> looks like a TIG welder on low current.
>
> I don't plan to use them in my F-250,
> Bryan