Water Injection

[William A. Sarkozy]

At 08:26 AM 9/6/96 -0600, you wrote:
>
>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
>
>
Your 2-stage idea is good, but I would use 2 pumps.....1 at moderate vacuum
and 1 at very low vacuum, each with its own regulating nozzle.  The idea of
modulating the motor speed (pump output) sounds good, but unless you have a
closed loop motor speed control for the pump, you're in for a suprise.
There are too many extraneous factors which will influence pump output
(nozzle position, temperature, etc.)  If you could call for a given motor
speed with a certain voltage, it would be great, but you
won't get 50 % motor speed by applying 50% voltage.  And you won't get the
response
you want either.  Also, I wouldn't key the water off throttle position....a
given throttle
position at heavy load can mean completely different operating
characteristics that the same throttle position at light load and high
speed.  Good luck.....

                                                                            
           Bill