Supercharger applications

[joeo]

Has anyone used water injection with a supercharger? I've read that one can install the nozzle(s) before the supercharger, and that it will help to seal up the rotors (roots type) and actually increase the efficiency of the blower slightly. Anyone have any experience with this?
Thanks.

[shoregtp]

Joe O,

I have a 2000 Grand Prix GTP. I am installing my system within the next day or so. I am spraying between the After the MAF and before the TB in a spacer.

Thanks,

Greg

[joeo]

Just to make sure I get it straight - the water will flow through the supercharger in this case? Thanks.

[Forum Admin]

Yes it would in this implementation.

[willwren]

I successfully built a water/alcohol injection system last year in my SSEi with an Eaton M62. I injected before the maf in the bend of my intake you see below (you can actually see the water injection line laying dormant in my sig picture, looped through the lid to my washer reservior).

This can help to keep your TB and SC clean, as well as no danger to the MAF (that I know of yet). I doubt you'd be injecting enough water to have a hydraulic sealing effect on the rotors in the SC.

I'm currently planning my next system. Early phases.

My original was leveraged off the fact that the SSEi comes with an Electronic Level Control system with the rear struts. This uses a compressor, and also has a utility inflator outlet in the trunk. I tapped into this circuit using a pressure switch, and pressurized a water tank in the trunk to deliver the water without the need for a seperate pump. Worked pretty well, but was complicated (including limit switches in the console shifter so it would only deliver in gear, not in P, R, or N).

I'd be interested in sharing experiences with other SC owners.

[SVO2GO]

Not sure where i read this but injecting water on the cold side damages the teflon on the rotors? I think on one of the GTP sites. I'll try and find the site and post it here. I know it's a no- no with a turbo. I've seen pics on a web site of the impeller damage (turbo) that had been injecting water before the turbo compressed the air. Not pretty but i'm guessing the impeller of a turbo spins much quicker then the supercharger rotors. On my SVO i installed the injector after the intercooler (already compressed air) but before the throttle body in the charge tube and seem to be having good results. Still tuning for power though. (hope i get max power before blowing it up!!) BTW excellent source of info on this site. Kudos to turboICE from another Jersey guy!

[Brad]

On the GTP cars it is hard to find a place after the supercharger to inject that will get all cylinders equally. That is the best argument for injecting before the rotors. It is possible to damage the rotors but the Aquamist nozzle makes a very fine spray. The biggest possible casue is letting the rotors get too hot then injecting water. If water starts before temperature get too high damage may be lessened.
In closing, injecting before the rotor has aways been a consern. I have two that come in to our shop that have had no rotor damage in 3 years.

[SVO2GO]

Thanks for the info, Brad. How much of a gain in power are you guys seeing with the water injection on the gtp's? I'm guessing it stops the computer from pulling timing with the cooler charge? I just finished installing a kit on my svo and was thinking about it for my gtp. Looking for small increase in power and will be installing a smaller pulley and k&n filter soon.

Thanks

[Brad]

I do not have any dyno number increase. Most cars we have been involved in would run full timing advance under full load. One user reported using 87 octane with a small pulley. He only got knock at thrttole tansistion then timing would come come back to the full advanced position.
Some cars running pulleys that would show 16psi on the gauge would drop boost to 13psi when the correct amount of water was injected. The boost drop was not a loose in air flow just a large decrese in intake manifold temperature. Like leaving your water bottle in the car on a hot afternoon and coming out in the morning and finding it collapsed.
The supercharger on GTP are basicly a positive desplacement pump so the air flow is the same just the temperature is dropped.
On turbo cars the turbo just keeps putting in more air to get boost to the preset limit.

[willwren]

As already stated, there really isn't anywhere to inject with an Eaton blower except somewhere before the TB, or into a TB riser plate. I have the L67 in my car, as well (But the Series 1), and ran mine about 5" before the TB. If you're going to do this, I strongly suggest removing the MAF screen. This can cause other problems, though, unless your intake is set up correctly. The MAF screen may defeat (to some extent) the fine mist an Aquamist nozzle produces, as droplets form on the screen in a re-constituted form. If you remove the MAF screen on an L67-powered car with a stock airbox, you will typically see an erratic idle. At the very least you need a 'gutted' airbox, but I suggest a mandrel-bent intake pipe with an open-element filter to get enough laminar flow in order to be able to remove the MAF screen with no ill effects.

The Teflon on the rotors actually serves no real purpose, as the rotors don't (or aren't supposed to) contact anything. The teflon is mainly (from my understanding) to prevent carbon buildup, which the water injection would solve, anyway. I ran my 3rd prototype system for 4 months last summer before rebuilding my Eaton M62 (not because it needed it, but for the benefit of the members of another automotive forum). I saw no negative effects on my rotors, which already had 80,000 miles on them.

I didn't do any in-depth testing on timing/knock, or dyno numbers, but my 'seat of the pants' dyno said I gained some significant performance. I'm in the process of planning another system, and now have a good scantool and G-tech Pro Competition to charactarize with this time.

The beauty of the SC application (roots, not CSC) is that you can inject before the rotors. With the turbo application, you're forced to inject after the turbo to prevent impeller damage, which requires a high-pressure pump. You can inject with low-pressure in the roots blower application. In fact, a simple venturi/vacuum feed actually works in this application. My first 'prototype' if you could call it that, was a simple bottle of water with a siphon tube inserted in the intake. It sucked water in by itself.

Because of the ease of injection with the roots blower application, it's alot easier to fabricate your own custom system.