someone has put the idea of a water cooled plenum in me head
that sounds interesting
well my water injection never turns on so guess its overkill but sounds real cool
Don't mate, waste of time.
Unless it has its own dedicated rad its pointless, using engine coolant will do the oposite of what you want.
Your water injection will be doing 10X (at least) what a water cooled inlet manifold will do, if you need a little more cooling use meth instead of water.
Rob,