Water vs Alcohol injection.

[wmc2004aug at bellsouth.net]

At 11:05 PM 6/15/2006, Ben Fenner wrote:
>How come the Nissan community has embraced water injection as the
>de-facto knock deterant? I've noticed the turbo Dodge, and Buick
>Grand National/turbo Trans Am crowd seem to prefer alcohol injection
>for this. As far as I can tell, alcohol injection has water

I'm gonna speculate a little here:  Water is one of the most bizarre
substances known to man.  It's heat capacity - the amount of raw heat
energy required to raise its temperature is around 5 to 10 times that
of almost any other substance.  It's heat of vaporization is also
absurdly high.  That's the heat required to change it from liquid to
gas, once it has reached it's boiling temp.  For water, using metric
figures, it takes (IIRC) 580 times the heat to change 100dC water to
100dC steam, as it does to raise liquid water 1dC.

Alcohols have much lower heat capacity and heat of vaporization.  So
my speculation is:  the water is a much better coolant, but alcohol
also cools to some extent and adds fuel and extra octane.

Ref:
http://en.wikipedia.org/wiki/Water_%28molecule%29
http://en.wikipedia.org/wiki/Methanol_%28data_page%29

    -Wayne  '06 RSX-S / 93 SE-R / '93 NK2k / '90 Miata