Listers:
uhhh.... Okay, I guess... I didn't think (in retrospect) that I made a very
clear case for anything in particular, other than "buyer beware". Let me try
to be more particular in why I find Jacobs' advertising generally
unpalatable:
1. FUD. (as in, Fear, Uncertainty, Doubt. Not anything else you may have
been thinking of)
A lot of their claims center on the fact that the "others" just zap the
spark plug with everything they can give it, all the time, while they give
the plug the "right" amount for all possible situations. Well, that's nice,
but has anyone actually had an MSD fry the electrode off their plugs or
"cause detonation through overheating the electrode" (as they claim it can
do)? Let's face it, the amount of energy dumped into the spark plug by a
firing impulse is likely small compared to the heat of combustion of the
cylinder's charge. If the energy put into the spark was comparable to what
the fuel/air mixture gave you then you'd have the most inefficient engine in
town. Therefore, "too much spark" is unlikely to ever damage anything.
2. Meaningless statistics.
Open circuit secondary voltage capability. The "others" have 20 or 30 kV
capability, while Jacobs' has up to a whopping 60 kV that is "adjusted
according to engine demand". Great! If you have an open circuit, you should
change your spark plug wires.
Spark duration with fouled plugs: The Jacobs system adjusts the duration
while the others just kind of futz along at a fixed duty cycle. Great. If
the plugs are fouled, they aren't going to fire until you clean the plug gap
anyway, and it's likely not the
ignition that's going to do it in the first place. If the mixture is so bad
(for whatever reason) that it's incombustible, then all the spark in the
world isn't going to light it off.
Spark Wattage: Somehow the Jacobs system can get over 2000 watts (their
scale becomes nebulous after that) out of the coil while other systems have
to content themselves with a mere 1200. Cool. Let's see... 1800 watts, at 12
V primary voltage, translates to 150 amps continuous input current into the
coil. Getting the graph scales right would go a long way to establishing
some credibility.
The "energy Paks vs. ordinary ignition" table: They have computer control,
and they parlay that feature into at least six comparison items, and somehow
the analog control that other units have doesn't even compare. I don't think
so.
Still, I won't necessarily write them off as "snake oil" (assuming I can
figure out what they mean by "phase angle" when it comes to firing a spark
plug), because a feedback controlled ignition system can do things ordinary
coil drivers can't. But their marketing does not impress me. Sorry for the
length of this rant.
Theo Smit
> -----Original Message-----
> From: Steve Laifman [SMTP:laifman@flash.net]
> Sent: Tuesday, November 30, 1999 2:28 PM
> To: Theo Smit
> Cc: 'Chris Mottram'; tigers@autox.team.net
> Subject: Re: Electronic Ignition or snake oil
>
> Listers,
>
> I bow to Theo's learned argument. If he doubts the claim, there is good
> reason to
> believe him. I guess that just because McDonald's has been in business a
> long
> time does not mean they make good food.
>
> Steve
>
> --
> Steve Laifman < Find out what is most >
> B9472289 < important in your life >
> < and don't let it get away!>
>
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