Water Injection

[Steve Ciciora]

O.K., My daily driver (w/ 160k miles) is starting to knock unless I use
premium.  I think I'll put in a water injection system, but have a few
questions.  Can you dump in too much water?  I plan on a winshield washer
pump, and to have it vaccum operated.  I will monitor the map signal and
start pumping water when the engine gets below a certian vaccum.  What
I could do with another op-amp and a 555 is have the water pump come in
at 50% duty cycle at one vaccum, and full on when it drops below another
vaccum.  I don't think I'll get carried away with using a pic chip,
because I really don't know the relationship between engine load and
knock.
  Would it be better to have the water controlled off throttle position?
Thanks for your time,
-Steven Ciciora