[Diy_efi] Water metanol turbo assist

[Greg Hermann]

At 4:19 PM 1/5/03, Derek wrote:
>> Fact is, when you are running heavy WI (read LOTS of H2O, _NOT_ "heavy H2O"
>> !!),  you don't NEED to run nearly so rich at WOT as youu do without the
>> H2O  !! The water is now doing the internal cooling, and the fuel for the
>> same purpose is no longer needed. 13.8 to 14.2 : 1 is PLENTY rich when
>> using serious, properly done WI !! This much rich is enough to allow
>> selective burning of the hydrogen in the petrol (and thus to take advantage
>> of hydrogen's higher heat of combustion compared to adding the second
>> oxygen to the carbon).
>
>I was told on this list not too long ago that extra fuel past stoich did more
>than just add cooling to the process.
>
>You saying that's all it provides?

I didn't say that. I believe 13.8 to 14.2 IS richer than stoich !! ??!! I
think I even explained the reason why the extra fuel makes more power ???
!!

 That the best AFR is stoich under all
>conditions, IF the air charge is well cooled for whatever reason below the
>temperature where detonation becomes a problem?

Again, NOT what I said. Nor did I say that charge cooling was the factor. I
DID mention "internal coolant"--as in absorbtion of heat (and reduction of
negative power requirement during the compression stroke) !!

>
>If so, then why are methanol fueled race cars used at a 5:1 AFR, rather
>than the
>stoich 6.45:1? Methanol at stoich cools many times better than gasoline at
>12:1.

Apparently because they like to have even MORE internal cooling, even
during the power stroke, fuel efficiency be damned.  Even at stoich (with
methanol), there is NOT enough heat available, even at 13 or 14 :1
compression ratio, to evaporate all of the fuel !!

Greg



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