"vairox" <nothere@spammasters.com> wrote in message
news:kfkn42tvaipokjplcnm1arlpqt85j3rehc@4ax.com...
> On Sun, 23 Apr 2006 13:33:47 GMT, "Elle"
> <honda.lioness@nospam.earthlink.net> wrote:
>
>
> what are the other causes of high nox? high combustion chamber temps
> due to carbon buildup is one but im not sure of any others
>
Technically, the causes are high temperatures and rapid cooling, which
causes the NOx to "freeze" instead of decaying as the gases cooled.

Since the expansion time is pretty much determined by engine speed, that
leaves combustion temperature as the factor we can control. Carbon really
isn't an issue directly, but it can cause preignition which has the same
effect as advanced ignition timing. The two big culprits are ignition timing
and mixture. Advanced timing increases combustion temperatures, and a leaner
mixture at high throttle settings (when it should be rich anyway to
forestall detonation) does the same. EGR reduces the temperature by diluting
the mixture without affecting the air/fuel ratio.

Mike