Running Rich - A noob question from an old fart

[Sharpie]

[Steve W2]

Originally posted by Digsy

I thouht that NOx emissions were cause by a fast, hot combutsion process? If that is true then woudn't a cooler burn reduce NOx?

 

NOx and HC emissions tend to be a trade-off. This is what EGR is there to control. I'm no calibration engineer but I would have thought that a slow, cool, rich burn would reduce NOx and increase HC and a fast, hot, lean burn would increase NOx and reduce HC.

 

By the way, if you are running so rich that you are getting bore wash, then you are running way, way too rich. Do people really go this far just to keep the EGTs down?

 

NOx is produced in a number of different ways. There is NOx that is created by the combustion process that converts the inbound Nitrogen content of the fuel, and there is NOx created by the heat of the reaction (Thermal NOx).

 

Thermal is caused when the reaction is hotter (generally speaking) which is why if you are running rich (cooler) the thermal NOx will decrease. The inbound Nitrogen conversion is only very minimally effected by the temperature of the reaction. In liquid fuels the conversion rate is very high (almost 100%).

 

Ian - yes CO2 will increase a fair bit. To quantify this though is pretty difficult.

[Justin]

I hit 1.7 bar at Pod on Hybrids. EGT warning light came on so I sh*t myself and let off the throttle. Didn't have time to look at the reading on my SAFC.

 

Power seemed to be low because my times were rubbish.

 

Have got 2 extra fuel injectors with controller too.

 

Will dyno at THOR next month and post up the findings.