I doubt you'll be able to feel any difference. But it sure does help when you're running hot. I have a Defi Water temp gauge tapped into my intercooler (range 20-120degC), a high pressure spray setup and a suction fan under the intercooler (much like the radiator fans, only smaller). You can never get too cool in the tropics!

If I leave the car parked for 20mins, the intercooler is sweating it at 75degC when I get back. If I get in and drive without using the spray, it takes a good 5 mins to get the IC temp back down to the 30's. If I pump it with water, it takes about half this time to get back down. If I use the fan its even faster, esp if the first few mins are spent in slow-moving traffic.

Do I feel a difference in power? No. But I'm surely running with a bigger margin from det! Don't forget, unless you det, the ECU will still run the std fueling and timing maps.

MY01 JDM STI RA.

[Edited by RT - 7/5/2002 3:09:16 PM]

 

As the very proud owner of an MY02 Prodrive Sti7, I have a very simple question for all you technical bods out there.

What the F***K does the intercooler waterspray do?

This is my second scooby, but the previous model MY01 WRX did not have this feature.

I have pushed this button when running hot and I have pushed this button when running cold, and it makes bugger all difference !!

Any Clues would be appreciated.

Darren

 

On a road car it does effectively nothing. The only time it would be useful is during those full throttle, full power, top speed, max acceleration moments. At times like this pushing a button that's hidden down by your left knee is the last thing on your mind.

So why's it there?

For the WRC rally car you can only use water cooled intercoolers if the road car has one. The difference is that once it's fitted you are allowed to change the method of operation. So the rally car will have the water spray pump controlled by some clever electronics, probably an extra output fom the ECU. The electronics will monitor the throttle position, the turbo boost and most important intercooler inlet air temperature and intercooler outlet air temps. When the circumstances dictate it the pump will be switched on automatically.

So why doesn't the road car have this? Easy, cost.

 

cheers guys think i may leave it a while.

 

Quote
"On a road car it does effectively nothing. The only time it would be useful is during those full throttle, full power, top speed, max acceleration moments. At times like this pushing a button that's hidden down by your left knee is the last thing on your mind."

Yes I agree its hard to hit. This is why I've moved my toggle-on switch to sit next to the handbrake lever just behind the gear lever, Evo style.

I don't know what comes with the STI UK. But my JDM STI RA has 2 modes.
1. A manual toggle switch (like a doorbell) which allows you to turn it on. It stays on for 5 sec after this switch is hit.
2. An auto mode selected by a 2 position auto/off switch. This triggers the spray with boost and rpm. If you turn it off then no spray is activated. Don't the UK cars have this?

 

Nope just the press once spray for X secs. As I said the bare minimum so that they can say the road car has water spray. No pres switches, temp switches or anything.

Oh and just realised it's my right knee....

 

Oh and also just remembered what someone who knows once said. The best performance upgrade for the intercooler spray is to keep using it a lot. When the tanks empty don't fill it and the weight saving will give you more of a performance gain than the spray...

 

Haha, very funny!

Anyway, to each his own I guess. For me, I believe in it as it gives me a fighting chance of "normal" intake temps with my climate + traffic. Guess if the British weather regularly gives you 10-15degC, then it may be of less benefit.

 

Yea I agree, if it was actuated by the boost, rpm, temps or some combination thereof then fine. If you have proper weather then even more fine. If you have to press abutton for 10 secs worth of spray and it's 10 degC and raining (ie UK summer) then probably less benefit.

 

Well cheers guys for all the helpfull technical stuff.

You have all answered very well, but I think my original comment was spot on. i.e. " Bugger all difference in normal driving"

Anyway, has anyone out there fitted any sort of automatic operation conversion to the UK Sti ?

Cheers
Darren

 

Just this evening on the way home from work, got stuck for 20mins in crawling traffic. My intercooler temps hit 60-odd degrees C. With the water spray and fan, they were brought back down to high-40's.

Ambient temp was 35degC, as indicated by the car's OEM sensor.

 

Hi
They use the waterspary system to try and keep the air intake temp down. As the charge temp rises, so does the chance of knock. So keeping the charge cooler allows you to run more advance, as well as increasing the density of the air, so there are more air molecules in the same intake volume, both of which give you more power!

You are right about the crap implementation of it though on the subarus. When we do a conversion to a 'rally car', we get the ECU to control the pump. It pumps only when 'on boost' and the air temp is above about 40degC. What you must remeber is that the top mounted intercooler, quite often becomes an 'interheater' which is just what you don't want.

There is power to be gained by keeping you charge temp as low as you can.

 

Don't worry about the 10degree hits the intercooler gets with water i will let you know on saturday what my -70degree hits of C02 spray gives

Scott