Location of nozzle in STi
 

Should the injection nozzle be installed in place of one of the press in steel bungs in the STi manifold downstream of the throttle body or in the rubber sleeve between the intercooler and the throttle body?

I can email a picture to anyone willing to discuss this with me.

im currently debating this on another forum too,

i think it also depends on if your doing water or water/alch, or just alch

When using a single jet or even paired jets from the same source - it is preferable to be as far from the ports as possible preferably before the throttlebody to ensure you do not get any rich/lean water mixtures in the cylinders.

Some have even put a jet at the turbo exit and after several pulls on a dyno without an IC fan the IC remained cool to the touch.

I can understand the appeal of one of the plugs on the intake - but unless you are sure that distribution to the runners would be even I would stay in front of the throttle body personally. Unless you are going to run it in a tuned port injection format, I would run it as a throttle body injection format.

I talked to the SMC owner, he said as close to the TB as posible (for pure alch) because your main benifit is the octane increase, not the cooling effect

with that in mind, and the cooling properties demonstrated by the dyno run test (no fan on the ic, ic cool to the touch) I was thinking about injecting a larger nozzel near the TB, and a smaller nozzel at the exitpoint of the intercooler (or maybe the exit of the turbo? not sure)

that way i would benifit from the cooling (via smaller injection of alch downstream on the after turbo IC piping) and the octane boost via the larger injector @ the TB.

Are there other considerations that could be involved? My car came non-stock turbocharged, as a result my compression's a high 10:1 and I'm using no intercooler. I've been running only one nozzle for a while approx. 6-7" away from the throttle body which includes one 90? turn.

I've been playing with the thought of downsizing from my 0.7mm jet to a 0.4mm and 0.5mm jet (lowering water pressure a bit too) and adding a second jet a couple of inches away from the compressor's exit.

Although, I have a couple of concerns. Upon deacceleration and the throttle plate closing, will some of the water from the jet close to the compressor be sent back into the wheel and possibly cause the wheel to crack or damage the seals? My BOV is currently situated in a place where it would be right inbetween both jets with about a 10" distance oh each side to the jets. Also, would the oncoming water/alch mix effect the seals in my BOV (it's a HKS pull-type).

My only guess would be to place it a couple of inches after the BOV so that it wouldn't interfer with the BOV upon boost and so all of it would vent out upon deacceleration.

Thoughts?

Re: Location of nozzle in STi
 

On a Subaru STI, installed a single alcohol injection nozzle in the underside of outlet tank of the IC. That places the spray pattern directly in the path to the opening (upstream) of the throttle body. That location is a turbulent area for very good mixing as the intake air is greatly accelerated into the throttle body. It's also a very neat looking solution.