pre IC spray

[LegacyGT]

I will be using factory TMIC and was wondering why people have said its a nono putting water injection before the IC...

i was thinking of 1 nozzle before the IC and one before the throttle body

[hotrod]

If you look at it from a simple thermal point of view, a given amount of WI following the IC should be better than (ie give more charge air cooling) than the same amount of injection ahead of the IC.

The analogy always used is if the spray cools the compressor discharge below the temp of the intercooler, the intercooler then acts as an "inter-heater"

I don't believe it is quite that straight forward and you should consider the option of trying both.

Everyone thinks in terms of the WI only effecting the engine but your dealing with a system that has several components. It may in your hot climate be worth while to give the intercooler a slight head start by partially cooling the compressor discharge under high boost conditions prior to the TMIC and see if the system "likes" the change.

What I would be inclined to do, is spray at both points, triggering the pre-throttle body sprayer first at your normal turn on ( ie 8 psi or what ever) and then try and see what happens if you trigger a smaller spray ahead of the intercooler under severe operating conditions like 12 + psi or where ever your turbo begins to rapidly loose effeciency.

If the air discharge from the turbo is 400 deg F a very small amount of water will knock it down to 200 deg or so, which the IC can take down near ambient with much less heat soak of the intercooler. This would also significantly change the flow velocity through the intercooler core, and I would think, reduce the high velocity "air flow drag" pressure drop due to the intercooler.

I plan to try that sort of arraingement when I get to that point.
Give it a try, you may discover something good!

Larry

[DuMaurier 7]

If you are planning to inject before the IC , why not go one step further and inject before the turbo ?, I have been doing this for a while and have observed no damage what so ever on the compressor blade (secret is to have good atomisation) . There are more benefits to be had by injecting there, namely a denser cooler charge entering the IC and less chance of condensation occuring , faster boost rise and less heating by the turbo . If you inject just before the IC and your IC is efficient enough you can actually get water dropping out of the charge air and collecting in the IC because of the minimal amount of time and mixing that is available , when you inject into the turbo there is more time for ALL the water to mix and become vapourised resulting in a more complete change of state and greater temperature change.

[LegacyGT]

thanks for the info... sounds good...

how do u ensure good atomisation? how far before the turbo did u inject the water... i have twin turbos so i might try the IC first...

but keeping an open mind

[wrx+]

Subaru Intake runners are long enough to insure a good mix as long as the injector is anywhere before the throttle body.

Kent

[SaabTuner]

Also, it may be desirable to spray pre-intercooler if you have an air/water intercooler.

The reason I say that is both water and aluminum conduct heat quite well. Air, on the other hand, does not. Allowing the water from the WI to pick up heat from the cool aluminum surface may make it very easy to reach 100% intercooling.

A good way to see if you should place it before or after the intercooler might be to see how well your intercooler is currently working. If it's already near 100% efficiency, injecting after the intercooler is probably a much better idea.

But again, like hotrod said, you can always try both ways without too much hassle, and see which works best for you.

Adrian~

[JohnA]

From my experience, if you're only running stock (ish) levels of boost, then spraying just before a good intercooler simply reduces the efficiency of the ic.
One hand giveth (spray), other hands taketh away.

At high boost levels though, when the intercooler is overwhelmed, then things would be different. It's a fine balance, like all things mechanical :wink: