[Diy_efi] WB-O2 with gasoline, nitrous and methanol...

[Mike]

I would imagine one of the biggest problems in using methanol is that
partial combustion generates a small amount of formaldehyde and that
AFAIK will poison most o2 sensors as the reaction at the sensor
produces an acid (not sure which) and that affects the reading
considerably as there is a current flow due to the acid and not
the o2 process... But depending on the sensor I suppose it can
be compensated for - maybe using two different types of sensors
concurrently and interpreting the differential(s)...

rgds

mike



At 05:58 PM 8/10/2002 -0400, you wrote:
>> Message: 7
>> Date: Tue, 08 Oct 2002 09:00:06 -0500
>> From: steve ravet <sravet at arm.com>
>> To: diy_efi at diy-efi.org
>> Subject: Re: [Diy_efi] DIY-WB and methanol
>> Reply-To: diy_efi at diy-efi.org
>> 
>> This was discussed on efi332 not too long ago.  The short answer is
>> that the calibration curve for the WB sensor is specific to gasoline. 
>> It's a measure of the partial pressures of the combustion products. 
>> Any oxygen introduced with the fuel will change the measurement.  The
>> efi332
>> archives aren't online yet, I'll see if I can find the post and echo
>> it.
>> 
>> --steve
>
>Ok lemme ask a couple questions to clarify:
>
>-"Oxygen introducted with fuel" - do you mean the nitrous, the oxygen 
>component of methanol or both?
>
>-"partial pressures of combustion products" - methanol will either burn to 
>H20 + C02 or not at all (ok maybe CO).  There doesnt seem to be any simpler 
>alcohols it can oxidise into without undergoing more or less complete 
>combustion.  How does this affect things?
>
>-So then am I correct in assuming its gonna be HELL to calibrate a WB-O2 
>for a engine that is receiving a mixture of gasoline, methanol and nitrous?
>
>-What would you reccomend for tuning such a beast?  My thoughts after 
>hearing your thoughts are as follows:
>1. Tune car NA with WBO2+dyno running pump gas to injectors
>2. Measure volumetric flow of nitrous at a given jetting by spraying for 
>(lets say) 60 seconds and measuring difference in bottle weight.
>3. Use ideal gas law to calculate how many moles of nitrous are used, and 
>use this to figure out approximately how many moles of oxygen are 
>introduced.
>4. Use moles of oxygen to reach a target methanol level such that methanol 
>+ oxygen added by nitrous is vaguely stoichiometric, with maybe a 10-20% 
>slant on the rich side favoring extra methanol
>5. measure flow of methanol through foggers with manifold off car using a 
>given jetting.  Play with jettings until methanol flow approaches that 
>theoretically calculated in step #4.
>6. Throw system back on car, hope nothing blows up.
>
>:)
>
>Feedback?
>-Dave
>
>
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Kind Regards  ~`:o)

Mike Massen
Network Power Systems
Perth, Western Australia  Ph/Fx +61 8 9444 8961

Power system in Jungle, Twin tyre car, Differential gauge
http://members.iinet.net.au/~erazmus/index.html

Some say there is no magic but, all things begin with thought then it becomes
academic, then some poor slob works out a practical way to implement all that
theory, this is called Engineering - for most people another form of magic.

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