[accre]

Okay, after looking at all of the fantastic responses on here I am convinced of the effectiveness of pre-compressor injection as a way to maintain the spool up of a small turbo while getting good top end performance. That being said, I am concerned about impingement.

I've just spent the last couple of hours on the Spraying Systems Co. website, and am very interested in their flomax air atomizing nozzles. Autospeed has an article about water injetion using one of this companies air atomizing nozzles using boost pressure as the air source. The Flomax nozzles work on pressures as low as 5psi, which I'm assuming is a pressure differential, so it means less than 5lbs of manifold pressure since the turbo is creating a vacuum on the intake side. They also are available in pretty small diameter spray patterns, and they make a 90 degree lance. I'm thinking that one could place the lance not far from the compressor, with the nozzle directed right at the center of the wheel. The fine spray (around 30 micron max from what I gather) combined with a targeded spray at the center of the wheel should make impingement negligable. They also produce nozzles that can be pulse width modulated like an injector.

how would you control such a system? I was thinking a small pre-compressor nozzle at high boost and rpm, and a larger nozzle (not air atomized) just after the intercooler that would be on more than the pre-comp nozzle.