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Re: Dual plugging. Was "Surge Free" spark plugs
- Subject: Re: Dual plugging. Was "Surge Free" spark plugs
- From: "Steve Makohin" <wateredg@xxxxxxxxxxxx>
- Date: Sun, 31 Jul 2005 12:02:02 -0400
Ben Barkow <dr.ben@xxxxxxxxx>:
> Ooops, sent it before I was done.
> If I may critique Steve's sense of geometry, the real full benefit occurs
> with THREE plugs, not two.
While I agree with the spirit of your statement, the words you have selected
may leave a reader misunderstanding it to mean that there is no real benefit
to dual-plugging, and that a "real full benefit" is only realized with
triple-plugging. All engineering exercises, when tainted with commercial
production concerns, are compromises between competing factors, such as
manufacturing costs, maintainability, aesthetics, etc. If you wanted to get
maximum theoretical benefit from multi-plugging an internal combustion
engine, you would have an infinite number of ignition sources, all
individually timed for optimum performance. A little common sense tells it
would be impossible to physically manufacture this theoretical model.
The addition of a second spark plug (i.e., dual-plugging) is not the
ultimate and perfect solution by any means. But even so, it provides
considerable tangible benefits while still being economically feasible, and
physically practical. While the addition of a third spark plug, or possibly
more, may provide additional benefits, that does not negate the fact that
just going to dual-plugging does the job very nicely, and gets rid of the
primary ridability problem (surging). I'd prefer not to start a thread on
speculating why BMW didn't go to triple-plugging.
> Ordinarily, adding plugs means you need to change the timing to benefit
> from the modified flame front. But this can nooot be done with Bosch!
> (Well, you can move the sensor plate a bit, I understand.)
The San Jose BMW dual-plug mod replaces a number of electronic components to
account for dual plugging. I do not know if the ignition of the two plugs
per cylinder is staggered or synchronized. Ditto with BMW's factor
dual-plugging scheme. I don't believe this distinction matters to the buyer.
Every one of the over dozen people I have contacted who have upgraded their
uni-plug Oilheads to a dual-plug configuration all say similar things, which
include the absolute lack of surging, new-found smooth running, and a "night
and day" difference before and after the mod.
> It is wrong to say that multi-electrode plugs have multi-source sparks.
> There is one and only one spark and having more electrodes does not
> result in more or better sparks. The electrodes shroud the spark (that's
> bad). The only advantage is that you have more metal and so the spark gap
> lasts through three owners instead of two. These are said to
> be helpful but I don't know much about them.
My understanding is consistent with yours. I am not sure if list members
have made the case that the multiple electrodes are the differentiating
factor. I think they just say a specific spark plug, like a certain model
Autolite, works for them. It's sort of a "black magic"solution (I am not
sure *why* it works, but it works.)
According to John Parker from Budds BMW (a professional engine tuner, NOT
just a mechanic), he says that it is possible that a certain model Autolite
spark plug may be effective at eliminating surging, but that the reason why
it works would not likely be the brand name of the plug or dual electrodes.
He says that the plug in question likely has a projected tip, and that
projection is what makes the difference, as it has in the solution he
devised for my bike.
- -Steve Makohin
Oakville, Ontario, Canada