erm, as in the title really. comparing gases from a dyno run and while the other gases all seem to make sense (higher HC at Lambda 0.88 etc) I can't make sense of the high CO2 and high O2 figures at Lambda 1? wouldn't the CO2 (produced by combustion) be higher at a richer figure and same for O2 being used up in said combustion?

Owain

 

anyone?

 

Because at 0.88 your running rich

So instead of CO2 (carbon dioxide) your getting more CO (carbon monoxide) and HC (Hydrocarbons - fuel/oil) - from incomplete combustion, due to lack of oxygen present...O2 (oxygen) will be lower as there isn't enough oxygen to combine with the carbon - thus also a higher HC (unburnt fuel)

High CO2 is a sign of complete combustion, so will be higher when the AFR is at the stoichiometric value (Lambda=1). Under perfect conditions O2 will also be higher as there is some left over after combustion. HC is lower as almost all the fuel is burnt correctly.

 

May develop more power at 0.88 due to burning all O2 in combustion which leaves unburnt HC and incompletely burned HC giving CO... As Ali said.

If you are maximising fuel use for economy Lambda 1 or lean burn you will not use all the O2 available in the combustion chamber - so O2 left over - but you should burn all the HC so all CO2 and no CO!

More CO2 in total is probably produced in the rich mixture but in a greater quantity of exhaust gas (including vapourised excess fuel) so the % is down a little... ?

Along the lines of a slice of toast having more calories per 100g than the slice of bread did before it ws toasted...

Mick