PICKLE

Hi, currently I have a DIY Water spray which is manually operated, as I have converted the headlight washers, to an I/C spray. Now I want to convert it so that it sprays automatically by boost pressure (as per STI) I am gonna use another bottle and pump, but where can I get a suitable Pressure Switch to activate the water spray at say 10psi ?? and where would it mount to sense the pressure?

Cheers,

john banks

Just put in a T-piece off one of the lines from the inlet manifold as you would for a boost gauge and hook this up to a pressure switch. Suggest specifying a switch that is rated to 100 Celcius and 3 bar absolute pressure with an adjustment screw. If you are stuck, then ERL/Aquamist sell one which is used to trigger Water Injection, which looks like a rebranded/restickered switch like you would get from RS for example. Just get a hose barb to fit 3.5mm approx ID pneumatic hose and you are sorted.

If you use a normally open switch that triggers at a specific boost level and the current capacity of the switch is sufficient for the pump (measure the resistance of the pump with a multimeter, use I=V/R = 14.4/measured resistance in ohms to give current in ampss) then you won't need a relay.

The pressure switch I am using has a 0.25A rating, so this would suit a pump with a resistance of at least 57.6 ohms for example.

Sorry if I'm teaching you how to suck eggs.

OTOH, a boost pressure trigger is arguably not the best way of doing it - do a google search on the Autospeed Intelligent waterspray for the reasoning.

PICKLE

John thanks for the reply, but I fear that I don't really understand fully??!! I was just hoping somebody would suggest a pressure switch to buy, and where to get it! I honestly didnt think it would be this complicated!--Not an expert on electrics etc.. What do the factory fitted cars use? eg Type R's etc Can I get hold of their kit?

Cheers

PICKLE

Right, I have had a look at the Aquamist/ERL website, and they offer 2 types of pressure switch which work at the pressure I need, question Is ;which do I need? One is usually open, and one is usually closed! What does this mean? Also, where would the switch screw into on the Inlet manifold? Do I just add a 'barb' as John described and tee into the vacuum pipe?

See www.aquamist.co.uk in the price list section for details.


[Edited by PICKLE - 1/20/2004 1:13:12 PM]

iain atkins

Pickle

I'm very close to Wiltshire, where abouts are you?

I have carried out this on my car, with a pressure switch etc. If you wish (and are not too far away) you can have a look at mine. I sourced a pressure switch from Novomec, and i can get you one if you wish.

I could also set it up for you if you like.

Mail me off line if interested




Iain