Mike,
There is a diagram courtesy of NGK in the tech section already. The picture
is here http://www.sentra.net/tech/images/chartheatratingflowpath.gif and
the page is here http://www.sentra.net/tech/sparkplugs.shtml .
I spoke with Joe Yoon from NGK personally to ask permission to use they're
tech write up on their plugs. He said we could use it as long as we gave
them credit for it. I just with you could edit the discrepancies that you
made me aware of.
Later,
Jason Bosaw
Co-webmaster
The Sentra Network
http://www.sentra.net
----- Original Message -----
From: "mike kojima" <[EMAIL PROTECTED]>
To: "Sentra Mailing List" <[EMAIL PROTECTED]>
Sent: Monday, May 21, 2001 10:54 AM
Subject: RE: SML-NON-P: spark plugs
> Dave is exactly right. When I have some time, I will
> put some pictures of hot vs cold plugs so you can see
> the shorter conduction path of the colder plug.
>
> Mike
> --- "Perron, Dave C" <[EMAIL PROTECTED]> wrote:
> > Thanks, Mike. I experienced some raised eyebrows
> > when I read this passage,
> > too. A spark
> > plug has just a (relatively) small copper wire down
> > the center, which would
> > act as just about the sole conduction path for heat
> > for the plug, as
> > compared with just more cylinder head. Where does
> > this wire (which by the
> > way is a lovely heat conductor) lead? To the spark
> > plug wire. Which is NOT
> > a good heat conduction path. The rest of the plug
> > is typically iron or
> > steel which doesn't conduct even as well as your
> > aluminum cylinder head.
> >
> > So I have to say the plug likely conducts very
> > little heat. The only heat
> > conduction path that has any potential puts the heat
> > right into your
> > distributor, which is not where you want it to go.
> > So, I'm going to make a
> > stretch here and say the idea that your spark plug
> > acts as a heat conductor
> > is totally incorrect.
> >
> > What is more likely is that your spark plug sticks
> > out into the combustion
> > environment and so gets a lot of heat loading. This
> > plug will eventually
> > come up to an equilibrium temperature that is a
> > function of its thermal
> > resistance to the prime thermal sink in that part of
> > the engine, which is
> > the cylinder head (and from there into the water
> > jacket). So a "hotter"
> > plug will likely have a higher thermal resistance
> > and will have a higher
> > equilibrium temperature. So the function of the
> > plug is NOT to conduct heat
> > out of the combustion chamber, but part of the
> > function of the plug is to
> > conduct heat out of ITSELF so that it operates at a
> > temperature that is both
> > efficient and not conducive to pre-ignition.
> >
> > This is just an engineer's assessment. As always I
> > have to defer to Mike
> > when it comes to how things REALLY work.
>
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Auctions - buy the things you want at great prices
> http://auctions.yahoo.com/
>
>
> +----------------------------------------------------------------------+
> To unsubscribe, put "unsubscribe" (by itself) in the subject and send to
> [EMAIL PROTECTED] or use the form at http://www.sentra.net/sml
>
>
>
+----------------------------------------------------------------------+
Have questions about your car? Try here: http://www.sentra.net
