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

[daveb at codyscafe.com]

> 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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