Re: Injecting prior to turbo comp' impellers
 

I think that this would be considered an internal mixing type and wonder if designed like the one above you could just increase the atomization of the standard nozzles by using air to further propel the atomized water. This type wouldn't rely on the siphoning effect of the venturi, and I think this is why the external mixing types don't require high air pressure. My theory could be wrong though. I haven't yet found the parts to start, as I'd have to machine a block that would allow insertion of the nozzle and keep the air separated in a separate chamber.

Without trying, I would think that the variables right now would be the effect the propulsion has on the spray angle, as well as whether the current jets spray angle is too wide and will make contact with the air holes. The concept seems sound though.

Re: Injecting prior to turbo comp' impellers
 

It is definitely internal. I did it for curiosity.

I like to hear how well the external type works if you mind posting some results. If the atomisation is good, the spray angle won't matter too much. hopefully it will be fog like. If it workout, you can PWM a valve to control flow.

Re: Injecting prior to turbo comp' impellers
 

I drilled out the nozzle orifice on my hvlp gun to insert a jet and tried it today.
I didn't have much time, but it seems as though the depth I place the nozzle matters. The atomization is increased slightly but I see the issue at heart. The dual air ports require that the liquid pass as the two air streams meet, and the water nozzle creates a fan. Only the water passing in front of the air focal point receives increased atomization. I think if there were small air ports surrounding the nozzle in a circle would work. I don't have the tools to build this though. Ill play with it more this weekend, but at the very least it has the standard atomization quality with some spots of improved atomization.

Re: Injecting prior to turbo comp' impellers
 

If the jet of water is narrow, there is a good chance the entire stream is atomised?

Re: Injecting prior to turbo comp' impellers
 

An easier way to think about is to design the air dispersing ports to cross the bulk of the water flow. Here are 2 external mixing nozzles

This one requires the water meet at the vertex of the air ports.
http://i281.photobucket.com/albums/k...ps90eb6760.jpg

This one seems like it would fit the existing aquamist nozzle, but it would require some thought into the angle of the air ports.

http://i281.photobucket.com/albums/k...ps5d19a291.jpg

I haven't tested it further, but I think you could make a modular system whereby your standing nozzle screws into an external mixing base. It would likely be the second type.

Re: Injecting prior to turbo comp' impellers
 

I like the multi-hole one, I think that looks wonderful.

You don't sleep much.

Re: Injecting prior to turbo comp' impellers
 

I'm a grad student, so no :)

Okay, I've been noticing decreased spool time (opposite from what I've read on some boards) and have the nozzle pointing directly at the center nut. This tells me that the integration and atomization are key. I'm injecting a total of 850cc of fluid with the preturbo handling 280cc worth of total flow.

4th gear
Post intercooler only:22 psi by 3600rpm
Pre turbo activated at 4 psi (with post turbo): 22 psi by 3400 rpm

I'm wondering if using stages would work better. I haven't inserted the logs into a dyno simulator yet to compare, but I suspect that having the post intercooler jets activate a bit later would help keep EGT a bit higher till full spool. I don't have curves to compare yet, but seat of the pants suggest that torque increases on activation of the pre turbo jet supporting increased mass flow rate with reduced compressor work.

I started playing with timing, increasing a tad during spool to account for the early turn on time. Since I have full pulsewidth control over the system, I have it reduced on the low end such that the flow rate ramps up pretty quickly but begins at a very low flow rate.

I think that the major factors that affect spool are as what everyone has been saying "atomization" at low flow rates. My thoughts right now are that if using a pump, a constant pressure system is the only way to go pre turbo. I can see how reduced atomization would slow spool with the reduced atomization till of course the pump pressure ramps up. Of course if one runs a mechanical system with an air atomizing nozzle the atomization is not a problem as water pressure and air pressure would rise 1:1 keeping atomization good as pressure rises.

My questions now are about calculating total flow rate between the two locations and what works best. Also what can I do to make a dual stage system out of the HSF2 using only one FAV? Can I place a solenoid right before the post intercooler jets to turn on at a higher point? I'm thinking that the PWM will no longer be linear with only one jet spraying and will have a dip once the solenoid opens.

One other thought would be to run 2 FAVs and have a Hobbs switch on one that completes the circuit at a certain pressure.

Re: Injecting prior to turbo comp' impellers
 

Hobbs and solenoid after the FAV should keep you PWM, unless of course you don't want that.

Re: Injecting prior to turbo comp' impellers
 

Such a nice thread and immense portion of knowledge I'll have to structure somehow in my head.

Anyway, having considered the effect of pre-turbo injection for my setup I decided to give it a go with the primary objective to increase the efficiency of the turbo compressor. To get a feeling on how the pre-turbo injection may work out in my case I'm currently planning to install additional jet pre-turbo (now running single jet post-IC for knock suppression reasons primarily) via a tee to existing line (post PWM valve). Would appreciate a practical advice from the people here.

In my setup I currently use single 0,8mm jet flowing ca. 420cc/min bearing in mind ca. 1,5 bar max boost I have. Is this a good idea to go with a 0,3 mm jet pre turbo, and change the post-IC jet to 0,5 (i.e. basically reallocate what I’m injecting now) or should I rather consider adding another jet on top of what I have?

Also, my system now is referenced to IDC (progressive). Based on my reading here I note that most people reference the pre-turbo injection to boost, which is reasonable given the amount should correlate with air mass rather than fuel. Is there a high chance I face any issues here due to changing AFR across the map?

Re: Injecting prior to turbo comp' impellers
 

Did some field testing last days.

A couple of words on the car setup: 2.0 lt engine with K04 based stock turbo, boosting 1,5 bar (midrange) and gradually decreasing to 1,2 bar on the redline (presumably due to turbo maxxed out flow-wise). WMI installed some months ago for knock suppression primarily, the map I have on the car (an I'm not able to tweak it unfortunately) appears to be pretty aggressive with 0,9 lambda (13,3 AFR) in midrange (which is also peak torque range obviously) and 0,8 lambda (11,8 AFR) in higher revs. Without WMI I have ignition retards of up to 12 degrees, with a single 0.9mm jet post-IC the retards become sporadic and mostly up to 4 degrees, which I reckon is acceptable. I inject 40% ethanol, 60% water.

The idea is to reallocate some injection to preturbo jet so that the effects on (i) knock suppression effectiveness may be tested (pre-turbo vs. post IC) and (ii) claimed increase of turbo capacity may be estimated.

I made test runs in 3 different setups:
1. Single 0,9 mm jet post-IC. Result: max. air consumption 790 kg/h, ignition retards up to 4 degrees;
2. 0,3 mm jet preturbo, 0,5 mm jet post-IC. Result: max air consumption 789 kg/h, ignition retards up to 8 degrees;
3. 0,5 mm jet preturbo, 0,3 mm jet post-IC. Result: max air consumption 791 kg/h, ignition retards up to 9 degrees in 1st run and up to 12 degrees in the second.

In twin jets setups (2 and 3) the 15psi checkvalve has been attached to the preturbo jet water line, the line to preturbo jet from the tee is also much longer. I verified both jets were flowing normally (controller in the test mode) but would expect in real life preturbo jet starts spraying with a delay compared to post-IC.

Based on above I may say that no turbo efficiency gain have been seen yet, however the detrimental effect on the knock suppression from shifting the injection to preturbo is pretty obvious. It would seem logical to increase the injection post-IC to fight the second (e.g. 0.5mm jet pre-turbo and 0.5mm or 0.6mm post-IC), I will further test this.

I have also encountered that the flow on the twin-jet setup was strange. After a periods of low load (car running but no water injection) when the WMI kicks in I get high flow for a second or so (up to 5 or 6 bars on the gauge), then it gets down to 3 bars and keeps like this to the redline. With a single 0.9mm jet I had generally linear flow increase up to 7 bars with the same SC setting. I will have a look into this as this may obviously affect the results.