Great link forwarded to me by Mr. J.C. Hassall, explain quite a lot, including
that "self-cleaning" temperature you refer to.
http://www.ngksparkplugs.com/tech_support/spark_plugs/p2.asp
-----Original Message-----
From: Tony Drews [mailto:tony@tonydrews.com]
Sent: Friday, April 24, 2015 11:21 AM
To: Barr, Scott; Randall; fot@autox.team.net
Subject: Re: [Fot] Spark Plugs
At the extremes - if you are getting detonation because the plug tip continues
to glow, go colder. If they are fouling (like with oil), go hotter. Had a
motorcycle that burned oil that would start running on 3 of 4 cylinders unless
I ran hotter than stock plugs to keep the oil burned off the tip.
Tony
At 09:52 AM 4/24/2015, Barr, Scott via Fot wrote:
>So, if the plugs are too dark despite your EGTs and/or air-fuel meter
>showing the mixture is good, would you move up a heat range?
>
>If not, what would indicate a need to change the heat range of your plugs?
>
>Scott (B.)
>
>-----Original Message-----
>From: Randall [mailto:TR3driver@ca.rr.com]
>Sent: Friday, April 24, 2015 8:31 AM
>To: Barr, Scott
>Subject: RE: [Fot] Spark Plugs
>
> > OK, so here's the stupid question of the day - what is it that makes
> > a hot plug "hotter" or a cold plug "colder". Is a "colder" plug
> > more resistant to absorbing heat? And if so, why?
>
>Basically, hotter plugs have more (thermal) insulation between the tip
>and the shell. Do a quick Google and you'll find lots of diagrams
>showing the longer/shorter path for the heat to follow.
>
>The reason for the differences in heat range (hotter or colder) is that
>the plug tip needs to get hot during operation, to burn away and
>prevent combustion deposits from fouling the plug; but not too hot.
>Stock engines tend to have relatively low temperatures in the
>combustion chamber, so use a hotter plug to avoid fouling. As the
>engine is modified for more power, the temperatures go up, and a colder
>plug is sometimes needed to keep the plug from overheating. Too high a
>temperature at the plug tip can damage the plug, but more importantly
>also lead to detonation. The plug tip can get so hot that it lights
>the mixture early (before the spark happens), causing loss of power and
>even engine damage.
>
>I also found that, with the MSD 6 ignition, colder plugs would last
>longer on the street, but of course that's not an issue with a race car.
>
>-- Randall
>
>_______________________________________________
>fot@autox.team.net
>
>http://www.fot-racing.com
>
>Donate: http://www.team.net/donate.html
>Archive: http://www.team.net/archive
>Forums: http://www.team.net/forums
>Unsubscribe/Manage:
>http://autox.team.net/mailman/options/fot/tony@tonydrews.com
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://www.team.net/archive
|