Peak temp of combustion

[Seth]

I don't think there is a perfect correlation between combustion temp and
NOx production.  At lambda 1.1, combustion temperature is still high,
but perhaps the excess oxygen contributes to the higher NOx.  I was
always taught a slightly fuel rich of stoich (mixture) was hottest. Too
rich and you waste heat, and imperfections in the homogenization of the
fuel and air in the intake charge result in un- or slower burning areas,
and lower peak combustion temp.  But if you want a high EGT, which isn't
exactly the same as combustion temp, as it is after expansion, all you
really need to do is retard the ignition timing.

just 2 cents worth

-Seth (the king of the comma splice)

Phil Lamovie wrote:
> 
> Perfect topic for flame war !!!
> 
> The highest combustion temps occur at Lambda 1.1
> 
> This also coincides with peak NOx development as NOx is
> temperature dependent.
> 
> Unfortunately for petrol it is also the highest thermal eff.
> 
> This gives rise to the expression " lean cruise " a trick the
> manufacturers use to artificially raise the fuel economy numbers.
> 
> The drive cycle test do not use a speed higher than 92 km/hr so the
> script kiddies at the ECU mapping centers write little algs such as
> 
> is vehicle speed 95 km/hr +
> is the engine temp over 65 deg/C
> has the throttle movt. been less than 5% per 10 sec
> is the rate of accel less than 5%
> goto lean burn table
> 
> Reason for the table is simple. The A/F ratio is beyond the range of
> that technological slight of hand the oxygen " switch ".
> 
> Phil
> 
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