I had/have an adjustable timer on mine, all I did was hit the button and it would stay on for 5sec (what I had it set to) want more water hit it again, a mate made it from a Jaycar kit but I was getting rid of excess wires under the dash one day and chopped the wrong ones so it hasn't worked for about 5yrs.

I really doubt it would make much difference cooling it off the line as it takes quite a while to drop temps even on the run - and they would throw you out of the drags if you dropped that much water on the track, I ran mine with a temp probe in the intercooler and it really didn't make a whole lot of difference without just about emptying the bottle.

I did all my testing on hot summer days so cold weather may make a difference but then again if mine gets a gut full of too cold air I get boost/fuel cut so it was never needed in this weather.

I actually bought a new 10" radiator fan to put under the offset top mount on the offroad WRX I had, I reckon this would work better but never got around to trying it.

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Beaten up old 98 Gen 2 Liberty, 13.0, stock V3 STI running gear.
07 Transit motor home
69 VF & 70 VG Valiants needing full restoration
Yamaha Zooma 50cc rocket hopefully going with the Transit.