Project GD STI, Adding an Intercooler Sprayer to a Front Mount Intercooler

Subaru STIs have a water intercooler sprayer as factory equipment.  There is an intercooler spray button on the dash with a large water reservoir in the truck with a pump.  When you push the button two nozzles spray a small amount of water on the intercooler for about 4 seconds.  The process is completely manual and kind of handy f0r c0ntroling heat soak for the factory interheater!  We call it that because a lot of heat from the turbo and engine bay cause the stock intercooler to sometimes get quite hot, limiting it’s effectiveness.  In fact converting the car to a front mount intercooler makes for huge gains in the power department on these cars for this reason.  The front mount works so well that when most people convert over to a front mount, they disconnect and or remove the intercooler spray system, us included.

Recently when tracking the car on a day in the high 90’s, on a higher boost pump gas map the water temps started to inch past the 220-degree point causing us to limit our sessions to 5 laps or so. If we were running E85 we probably would have been ok but there were no E85 stations around the track and well, we were lazy. We have since developed a thermal management map where we run less boost and more spark advance than stock but with still over 400 whp but we wanted to have more options to cool the car.  We decided to reactivate the spray system so it could cool the intercooler and the radiator as well.

We decided to mount some nozzles in the front bumper.  To make installation easy, we opted for these Jeep headlight washer nozzles.  We got them from for something like $12

One reason we went with these nozzles is that they are an easy installation, they just need a hole. Most washer nozzles have a vehicle-specific design and need a hole with clearance slots for mounting tabs that work best on a certain thickness of the mounting surface.  It is a lot easier just to drill a hole.

Another reason why we chose these nozzles is that you can adjust the flow using these screws, just like your sprinkler heads.


  1. so i have a GRB rally car and my intercooler spray is connected to an indicator relay so when it is activated, it sprays intermittently….could be something to think abot

  2. I wonder if the spray pattern as well as atomization matters? The picture shows a rather concentrated stream into the FMIC. Does a finer mist mean more surface area, and more effective cooling?

    1. Probably doesn’t matter a lot at speed, we wanted the spray to go through the IC and hit the radiator too. Mostly chose those nozzles because ease of install too.

    1. The factory uses this system, this is just re-enabling it for a front mount IC instead of the OEM top mount. The WRC cars used it so the factory added it to the production cars. Water injection is something totally different

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