Les Myer wrote:
> Where's an engineer when you need one :-)
I have a Computer Engineering degree, so maybe I can't answer your
question but I can design an embedded computer to simulate it
on the fly!
> The question about "why then did the new cars go to wider gaps (ie 0.045)"
> is a really (really, really) good one. Made me go hmmmmm for a while,
> grasping at mental straws to support my position - but I thought of one
> after a while. Here it is. I think it is probably because with tight
> emissions the engine is run leaner than they used to
Just a slight caution, "lower emissions" doesn't necessarily
mean "leaner", since running lean actually usually causes a huge
leap in NOx emissions.
My guess would be that since modern cars all use electronic ignition,
big sparks are no problem. With points ignition, you are always fighting
a battle where the more spark you want, the more current passes through
the points and the quicker they wear out.
Since big sparks are essentially free, why not go for big
gaps? This also helps instant starting which is something people
have come to expect from cars.
I would like to point out that, although I can't remember the
source, I have read that humans often cannot detect misfiring
even with rates as high as 15%.
....so.... I guess that means that just because you can't TELL
your car is misfiring doesn't mean it isn't misfiring as often
as say, one in ten sparks.
You might not notice ignition problems, but it might be costing
you power and emissions, as well as mileage since fuel not ignited.
is fuel that doesn't help the car move forward either.
--
Trevor Boicey, Ottawa, Canada.
tboicey@brit.ca, http://www.brit.ca/~tboicey/
[ Seeking some miscellaneous MG parts, see the list on the web page... ]
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