Toyota Supra twin turbo and water injection.

[Robert Harris]

Provided of course that the exhaust gas temperature remains the same and you
are correcting to stoich.  If you are biasing toward rich - which under load
most are - you will find that the output is temperature sensitive and your
mixture will be off.

A .8 equivalence ratio ( about 12.~ to 1 ) is ~1.0 volts at 500c exhaust but
only ~.875 volts at 900c.  At 900c the transition from stoic voltage is about
650 mv but at 500c its all the way up to 850+mv.   

Adding water or alcohol will lower the combustion and generally the exhaust
temperature.  If you are uncompensated for EGT, this will mean for the same
output of the sensor, the mixture will be leaner.  

Reference: Internal Combustion Engine Fundamentals
John B. Heywood - Director Sloan Automotive Laboratory MIT
ISBN 0-07-028637-x

Virtually all O2 sensors appear to be uncompensated for temperature with the
heater bringing them somewhere in the "warm" region.  For the manufacturer
this is not a problem as they simple use them as a stoic switch.

>Date: Sat, 3 Apr 1999 16:14:27 -0700
>From: bearbvd at sni.net (Greg Hermann)
>Subject: Re: Toyota Supra twin turbo and water injection.
>
>>In article <4.1.19990403143820.00951540 at mail.lig.bellsouth.net>, David A.
>>Cooley apparently wrote:
>>
>>> How about substituting Methanol or Ethanol for the water... higher heat of
>>> vaporization (cools better as it evaporates) Plus it supplies additional
>>> fuel to the engine *AND* increases effective octane of the cylinder
>>> charge... Pretty good gains to be seen here if it's metered right!
>>
>>That is pretty common over here in the UK.I do not know if such additives
>>would be "liked" by the Lambda sensor though? Anyone ?
>
>No problem there--fact is, the sensor will read the true stoich point,
>despite the new fuel.
>
>Greg


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