Water injection on 18psi supercharged 1600cc (Toyota 4AGZE)

[nick.parker]

Hi,
Just looking for some advice or reasons for the behaviour I have experienced. My Toyota 4AGZE engine is running a large supercharger giving 18psi boost pressure. Without doing anything else but turning on the water to a 0.4mm aquamist nozzle (from a 100psi water reservoir) the torque decreases quite noticibly (from the seat of the pants). The water sprays just after the throttle so goes through the supercharger, water to air intercooler then inlet manifold.
I noted that boost pressure increase 10kPa or so at the manifold with water injection active.

Has anyone experienced this loss of torque on their engine? What are reasons? Too much water?, too rich to start with, not enough advance?

Thanks, Nick