This is an idea I came up with during my MR2 days. In that application intercooling is very difficult to do adequately and the compressor outlet is extremely close to the throttle body, given that and my budget-mindedness I came up with the following:

1. Water reservoir with a check-valved manifold reference (pressure can enter the reservoir)

2. Nozzles from reservoir connected to intake on the compressor inlet

Basically as pressure builds in the intake manifold the reservoir will pressurize as well and inject water into the intake tract pre-turbo. Obviously the jetting would be completely different from a high pressure system and it would probably be advantageous to run multiple nozzles controlled with pressure switches or something similar...

Just an idea I've had bouncing around in my head for the last 5 years or so. Something I might try on my next budget turbo build.

Any input? Has it been done before?

 

So basically... a leaking recirculating BOV with a water tank in the recirc line
I imagine the end result will be more akin to blowing through a straw into a carton of milk than a functional WI system.

 

Yes it has been done Markp touts it very highly i have my doubts as to wether is will be as effective as the traditional pump systems. Or provide enough flow to do any good though. + shooting pre turbo is asking for trouble as the water will have a hard time stay suspended there.

 

What sort of pressures are the real systems running?

My experience with water and alky injection is a Supra I did a few years ago. Seems like I remember 60 psi being what it ran but I'm not sure. But thats working against 38 psi that we ran on the car.

With the MR2 I had planned on running about 30 psi which would give me more of a pressure differential than the setup above (if I remember that pressure correctly) and it would be progressive. IE more boost I run the more pressure I get in the tank and the more water that is injected...

An open carton of milk isn't sealed and water can't be compressed so it would be completely different.

Atomization would be the only real issue... and finding the correct jet size with out any real info to draw from.

 

These run at over 100 psi. There use to be a picture floating around of an erroded compressor wheel from injecting water through it. No idea if that was distilled or tap though.

 

Hmm. Yeah I could see compressor speeds being an issue. I've been talking to people about this today. Turns out a V8 tuner I know was doing this in the 60s on supercharged cars with good results. Didn't think to ask but I assume it was on a Roots style which would be more robust than a turbo fin...

 

Spraying through a PD charger works awesome. I would even say its my preferred way.

 

Damn. Should have done this when I had my SC... but I had a shelf full of free intercoolers and didn't even think of it.

 

That's what I've always heard, and I've always wanted to do it anyway - that you'd wreck the blades on the turbo, especially if you get any 'big drops'.

There is one nice thing about it, it's self regulating, more boost is when you need more water, so it will be somewhat proportional. Maybe put a carburator in there, and feed it with water. Then it will atomize fine, for sure. :-)

Pardon the thread highjack:
How do you tune for WI anyway? As I understand it, O2 sensors don't work right with water in there, so.... How do you know where you are?

 

Probably doesn't matter, but the last comp wheel I bought was maybe $56.00But it might have only been $30 or so...