UEGO and alcohol

[Matt Beaubien]

Bruce,

[Sorry if this is a repost, but I didn't see it go
through the first time.]

>>That is gonna be the biggest handful to get right,
that you can 
imagine, IMO
The ports need to be rather large to allow any air
into the motor you 
got so
much fuel displacing the volume of air that engine can
even see.
<<

This seems to be a pretty common misconception.  If
you do the calcs for gasoline, the volume of fuel vs
volume of air is <<1%.  Even if doubled for alcohol, 2
* <<1% = <<1%.  

>>Just don't know how you can look for a *average* AFR
that will make 
sense
with 2 fuels.<<

Agreed.  However, Lamda would make some sense.  While
not as commonly used, it is easier to compare mixtures
between two different fuels.  Max power on gasoline is
~0.85 L, which is ~12.5:1 AFR.  Same goes for alcohol
(i.e. methanol).  Max power is ~0.85 L, which is in
the 5-6:1 AFR.  If you combine the two in a combustion
chamber (ignoring NO2 for the moment), you could look
at the Lamda value for how much above/below stoich you
are at.  If the meter will only read in AFR, divide by
14.7 to get Lambda.

Mix NO2 into the combo and EGT is certainly another
important (the most important?) indicator.

Matt Beaubien
'73 911E
'86 5kt




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